64. "On narcotism by the inhalation of vapours"

Source: Snow, John. London Med. Gazette 47, 11 April 1851, pp. 622-27 (Part 16).

By John Snow, M.D.

[Part 16]

Experiments to determine the amount of Carbonic Acid Gas excreted under the influence of Chloroform--of Ether.-- Diminution of Carbonic Acid caused by Alcohol.--Chloroform, Ether, etc., produce their effects by diminishing Oxidation in the system, without necessarily combining with oxygen themselves.--Proofs of this view.

In order to ascertain with accuracy the quantity of carbonic acid gas excreted by animals whilst under the influence of chloroform and ether, I employ some apparatus similar to part of that used by MM. V. Regnault and J. Reiset in their chemical researches on the respiration of animals* (*Annales de Chimie et de Physique, 1849).

The accompanying engraving will assist to give a correct idea of the apparatus. The animal to be experimented on having been placed in a large glass jar, the latter is covered with a lid, padded on its under surface with an India rubber cushion, to make it fit accurately. In this lid there are three apertures. One of them serves for introducing the chloroform or ether, and can be closed by a brass mount; the others are connected, by means of tubes of vulcanized India rubber, to a potash apparatus, consisting of two glass vessels with an opening at each end, connected together at the lower part by means of another elastic tube. The solution of potash employed is diluted with sufficient pure water to make it fill one of the vessels; and as these vessels are made to move up and down during the experiment, by means of a cord passing over pullies, the solution of potassa is moved alternately from one vessel to the other, its place being occupied by air from the jar, which is returned back again as the vessel descends and becomes again filled with the liquid. As the tube from one of the potash vessels is continuous with one which descends nearly to the bottom of the jar containing the animal subjected to experiment, air is alternately withdrawn and returned at its upper and lower part. A constant circulation of air thus takes place, and the carbonic acid gas becomes absorbed soon after it is given off from the lungs.

To determine the quantity of carbonic acid gas taken up by the solution of potassa, it is first put into a flask and boiled, to expel the chloroform or ether it may have absorbed. The flask is afterwards closed with a stopper, perforated for the admission of a safety tube, and a tube containing chloride of calcium* (*See figure at the left side of the engraving). The whole is then carefully weighed, together with a bottle containing rather more dilute sulphuric acid than is sufficient to saturate the solution of potassa. The acid is introduced gradually through the safety tube, and the contents of the flask heated to the boiling point, in order to expel the whole of the carbonic acid gas from the liquid. By making aspiration through the chloride of calcium tube, the whole of the carbonic acid is removed from the flask, its place becoming occupied by fresh atmospheric air, which enters through the other tube. When the contents of the flask have cooled to the temperature at which the previous weighing took place, the apparatus is again carefully weighed, and the loss of weight shows the quantity of carbonic acid known to have been contained in the solution of potassa employed, the remainder shows the quantity which has been absorbed by it during the experiment.

Exp. 70.--On December 18th, 1850, a rabbit, weighing four pounds, was placed in a jar holding 1,600 cubic inches, and allowed to remain for half an hour, the potash apparatus above described being kept in motion during this time. The rabbit was very quiet during this part of the experiment.

The potash vessels having been emptied and replenished, and the rabbit having been removed for a few minutes for the ventilation of the jar, it was put in again, and twenty-five grains of chloroform were introduced through the aperature in the cover. The vessels containing the solution of potassa were kept moving up and down, as before. The rabbit moved about briskly on the introduction of the chloroform, and continued to do so for six minutes, after which it lay apparently asleep, but started spontaneously, now and then, as if in a disturbed dream. On its removal it showed signs of sensibility when touched, but appeared quite unconscious.

After being put out of the jar for five minutes, and the jar having been well ventilated in the meantime, the rabbit was put in again, in much the same state as when removed. It remained for half an hour, sleeping the greater part of the time, but had almost recovered from the effects of the chloroform on its removal. The potash apparatus was in action as before.

The solution of potassa employed in the different parts of the experiment was analysed, with the precautions before described, and gave the following results:--

The quantity of carbonic acid gas absorbed in the first part of the experiment, before the exhibition of chloroform, was 0.80 grains. In the second part of the experiment, during the inhalation of chloroform, 2.78 grains were absorbed; and 2.85 grains after the inhalation, whilst the rabbit was gradually recovering.

Exp. 71.--On December 21st, 1850, a young dog, weighing eight pounds, was placed in the jar holding 1,600 cubic inches, and allowed to remain half an hour, the potash apparatus being kept moving, as in the previous experiment. The dog whined and turned round occasionally, but did not make much muscular effort.

The dog having been removed for a few minutes in order to ventilate the jar, was put in again, and twenty-five minims (thirty six grains) of chloroform were introduced. The potash apparatus, which had been replenished, was moved up and down as before. On the introduction of the chloroform the dog made violent efforts to escape, and his muscular exertions continued, when they were no longer directed by consciousness, till he sank down apparently insensible at the end of about eight minutes. The head and limbs, however, continued to be moved occasionally during the remainder of the half hour. On his removal from the jar the dog yelped, but his muscles were quite flaccid, and he lay for a time where he was placed, and afterwards recovered gradually.

The solution of potassa employed in the half hour just before the chloroform, was found to have absorbed 10.1 grains of carbonic acid, whilst that employed for the same period with the chloroform had absorbed only 4.8 grains.

Exp. 72.--On January 19, 1851, a cat about half-grown was placed in a jar holding 920 cubic inches, and allowed to remain for half an hour whilst the potash apparatus was in operation, as in the other experiments. The cat made occasional efforts to get out of the jar.

A few minutes after its removal from the jar, the cat was put in again, and twenty grains of chloroform were introduced through the aperture in the cover. The potash apparatus, having been replenished, was kept in motion, as before. On the introduction of the chloroform the cat made violent efforts to get out. In two or three minutes it became unconscious; but it continued to move involuntarily until five minutes had elapsed, when it sank down in a state of insensibility. During the remaining twenty-five minutes of the experiment the breathing was quick, and much deeper than natural. The cat was quite insensible to pricking and pinching on its removal.

The solution of potassa employed just before the chloroform was given absorbed 5.7 grains of carbonic acid gas; whilst that used during the time that the chloroform was exhibited, absorbed but 2.0 grains.

Exp. 73.--On Feb. 17, 1851, a cat weighing four pounds and a half was placed in the jar holding 1600 cubic inches, and kept there for half an hour. It sat very quietly the whole time. A few minutes afterwards it was put into the same jar again, and eighteen grains of chloroform were introduced by the aperture in the lid. The cat moved about somewhat during the first seven or eight minutes, but it lay sleeping the remainder of the half-hour: it was not insensible on its removal, but inclined to sleep when not disturbed. The cat, having been removed for a few minutes to ventilate the jar, was put in again, and twenty-seven grains of chloroform were introduced. The cat had in a great measure recovered from the effects of the former dose of chloroform during its removal: it attempted to escape on the fresh chloroform being introduced, but soon became quiet and apparently insensible. At the end of half an hour the solution of potassa was changed, without removing the animal from the jar. Chloroform was now added by ten minims at a time, about every ten minutes, till the cat was killed. It died very gradually at the end of three-quarters of an hour. The breathing became very feeble, and intermitted, for long intervals before death took place, and there were no gaspings.

The potash apparatus was in operation during the experiment, and the analysis of the solution of potass gave the following results:--

Carbonic acid gas excreted in half an hour, just before the chloroform, 7.7 grains.

In half an hour, with eighteen grains of chloroform in the jar, 5.7 grains.

In the same time, with twenty-seven grains of chloroform, 4.9 grains.

During the last three-quarters of an hour, 7.1 grains, which is at the rate of 4.7 grains for half an hour.

It will be observed that the quantity of carbonic acid gas excreted under the influence of chloroform was considerably less in all the above experiments than it had been just before; and in the last experiment, it will be remarked that the excretion of carbonic acid kept diminishing as the narcotism increased; whilst in Exp. 70 it increased somewhat during the last stage of the experiment, whilst the effects of the chloroform were subsiding.

It would not be easy to make correct experiments for ascertaining the amount of carbonic acid gas excreted by patients whilst under the influence of chloroform; and my inquiries on this point in the human subject have been confined to such experiments as I could conduct on myself whilst slightly affected by the vapour.

In two experiments related in the last part of this series of papers,* in which oxygen gas was breathed to and fro over solution of potassa, whilst under the partial influence of chloroform, the amount of carbonic acid absorbed by the potash was determined in the manner described above, for comparison with that absorbed in experiments conducted in a similar manner a little time before the chloroform was inhaled.

(*[part 15]; Medical Gazette, last vol. p. 753).

The quantity of carbonic acid as is shown in the following table:--

In Exp. 67, for instance, 42 grains of carbonic acid gas were absorbed by the potash whilst breathing oxygen for ten minutes before the chloroform had been inhaled, and only 33 grains during the same period, just after the inhalation of chloroform. A similar diminution of the amount of carbonic acid took place in Exp. 68.

In the subsequent experiments enumerated in the table, the air was inspired by the nostrils and expired by the mouth, through a glass tube which conveyed it through a solution of potassa placed in two Woulfe's bottles. The experiments were made at ten or eleven o'clock in the evening, after sitting quietly for two or three hours. The breath was passed through the solution of potassa before inhaling, and then through a similar solution, after inhaling as much chloroform, for three or four minutes, as could be taken without causing unconsciousness. An inspiration of chloroform was also taken, now and then, during the remainder of the experiment, to prevent the effects of the vapour from altogether subsiding.

Soon after the introduction of the introduction of the inhalation of ether, I made some observations on the amount of carbonic acid gas exhaled from the lungs under its influence, by passing the expired air through lime water, when I found the quantity to be diminished.*

(*See Report of Westminster Med. Soc. in Med. Gaz., Feb. 26, 1847).

The following more recent experiments on animals have been attended with a similar result.

Exp. 78.--On Dec. 15, 1850, a rabbit, weighing four pounds, was kept in a jar, of the capacity of 1600 cubic inches, for forty minutes, the potash apparatus, before described being in motion all the time. The rabbit was perfectly quiet. Soon afterwards, the rabbit was put into the jar again, and forty grains of ether were introduced, which did not cause insensibility, but only inebriation. The rabbit remained in a position between sitting and lying, being able to hold its head up. It was removed at the end of forty minutes.

Twenty minutes after its removal, when the effects of the ether had almost altogether gone off, the rabbit was a third time placed in the jar, for the space of forty minutes.

The analysis of the potash employed in the first part of the experiment, before the ether, yielded 12.6 grains of carbonic acid. The carbonic acid given off during the inhalation of ether was not correctly determined, owing to an accident; but that employed in the third part of the experiments yielded 10.8 grains, showing a notable diminution, although the effects of the ether on the animal had almost ceased to be perceptible.

Exp. 79.--In March, 1851, two pigeons were placed for twenty minutes in a jar holding 670 cubic inches. They stood still the whole time. A few minutes after their removal they were put into the jar again, and sixty grains of ether were introduced, at short intervals, by a few grains at a time. The pigeons became gradually insensible, and at the end of eight minutes were lying on the side. They showed no signs of sensibility when removed at the end of twenty minutes, but lay where they were placed. After being out for three minutes, they were put into the jar again, as they were beginning to evince signs of returning sensibility. In ten minutes more they were able to stand, but they were not fully recovered, when they were removed, at the end of twenty minutes.

The potash apparatus was in action, as in the previous experiments. The solution of potassa employed in the first part of the experiment absorbed 6.1 grains of carbonic acid; that employed in the second part absorbed 3.6 grains; and that employed in the last part of the experiment, whilst the effects of the ether was subsiding, absorbed 4.4 grains.

The late Dr. Prout discovered, nearly forty years ago, that fermented and spirituous liquors diminish the amount of carbonic acid given off from the lungs. He summed up the result of his experiments on this point in the following words:--"Alcohol, in every state, and in every quantity, uniformly lessens, in a greater or less degree, the quantity of carbonic acid gas elicited, according to the quantity and circumstances under which it is taken."* Dr. Prout's experiments were confined to the proportion of carbonic acid gas in the expired air.

(*Ann. Phil. vol. ii. p.336).

A recent German author has extended his inquiries to the quantity exhaled in a given time, and he finds that both the proportions in the expired air and the quantity excreted per minute are diminished during the action of alcohol. He also finds that the total amount of every one of the constituents of the urine is lessened, under the same circumstances.†

(†Beiträge zur Heilkunde nach eigenen Untersuchungen von Friedr. Wilh. Böcker. Crefeld, 1849).

I am indebted to the kindness of Dr. Bence Jones for the knowledge of this work.

The diminution of the amount of carbonic acid formed in the system under the influence of chloroform, ether, and alcohol, taken in conjunction with a circumstance shown in a former paper, that the chloroform and ether are exhaled unchanged from the blood, assist to prove a view of their modus operandi which I suggested with respect to ether, early in 1847.‡

(‡See Med. Gaz. vol. xxxix. p. 383).

That view may be stated as follows.

Chloroform, ether, and similar substances, when present in the blood in certain quantities, have the effect of limiting those combinations between the oxygen of the arterial blood and the tissues of the body which are essential to sensation, volition, and, in short, all the animal functions. The substances modify, and in larger quantities arrest, the animal functions, in the same way, and by the same power, that they modify and arrest combustion, the slow oxidation of phosphorus, and other kinds of oxidation unconnected with the living body, when they are mixed in certain quantities with the atmospheric air.

This explanation is probably applicable to the action of all narcotics whatever, but is here applied only to the class considered in these papers, namely, the volatile narcotic substances not containing nitrogen, or those substances whose power was found to be in the inverse ratio of their solubility in water and the serum of the blood.

The circumstances which appear to my mind fully to establish the above stated theory of the operation of chloroform and similar bodies, are enumerated in the following propositions:--

Sensation, motion, thought, and indeed all the strictly animal functions, are as closely connected with certain processes of oxidation going on in the body, as the light and heat of flame are connected with the oxidation of the burning materials.

The diminution of the amount of carbonic acid gas excreted by the lungs under the influence of chloroform, ether, and alcohol, shows that the processes of oxidation going on in the body are lessened, for the amount of carbonic acid given off has a pretty close relation to the quantity of oxygen consumed.

The diminution of temperature in animals under the influence of chloroform and ether, alluded to in an early part of these papers, also shows that the processes of oxidation which take place in the body are diminished, since the development of animal heat has been shown, by Edwards and others, to have a constant relation to the quantity of oxygen which is consumed in respiration.

The venous blood in patients under the influence of chloroform or ether is less dark in colour than in the normal state; indicating that those changes in the blood which take place in the systemic capillary circulation are diminished.

The lessened quantity of all the constituents of the urine, observed by Böcker, from the effects of alcohol, also shows that oxidation is diminished.

The diminished oxidation is not owing to the combination of the narcotic substance with the oxygen of the arterial blood; for in the first place, the chloroform and ether, as well as part of the alcohol, have been shown to escape unaltered in the breath; in the second place, the quantity of material, in the case of chloroform, capable of combining with oxygen, is altogether insufficient so to appropriate the oxygen; and in the third place, to increase the amount of oxygen in the respired air does not prevent the action of the narcotics.

The different parts of the nervous system lose their power under the influence of the narcotics we are considering, in the same order as in asphyxia--the privation of oxygen, as was observed by M. Flourens with respect to ether, in 1847*.

(*Gazette des Hôpitaux, 20 Mars, 1847).

The muscular irritability, which continues for a short time after death, depends on the action of a little oxygen still remaining in the system; and this irritability can be at once extinguished by chloroform, ether, or alcohol, in proportion rather larger than is necessary to cause death. When the muscular irritability is thus extinguished, post-mortem rigidity comes on almost immediately, and lasts for an unusually long time, if the narcotic employed is prevented from evaporating.

The vapours of volatile narcotic substances have the property, when mixed with the air, of retarding, and, in larger quantity, of arresting, that form of oxidation which constitutes ordinary combustion; and their power in preventing combustion generally bears a direct relation to their narcotic strength.

Many of these same vapours have the property of preventing the slow oxidation of phosphorus, which renders it luminous in the dark, as was discovered by Prof. Graham; and their effects, in this respect, have a general relation to their narcotic power.

The putrefaction of animal substances consists, on its commencement at least, of a process of oxidation; and the numerous class of substances we are considering all have the property of preventing putrefaction, their antiseptic power having generally a direct relation to their narcotic properties.

The reduction of the temperature of the body, by exposure to cold, diminishes the consumption of oxygen, and causes symptoms very nearly resembling the effects of a narcotic.

The second and sixth of the above propositions have already been fully considered, and the remainder will receive further consideration in my next paper.

(To be continued.)

65-66. "On the mode of propagation of cholera."

Source: Snow, John. Medical. Times 3, 29 November 1851, pp. 559-562 (Part 1), 13 December 1851, pp. 610-612 (Part 2).

Read at the Epidemiological Society of London, 5 May and 3 June 1851. See part 2, p. 610, for Snow's discussion of a water-supply map from the 2nd Health of Towns Report (1845) and Grainger's map (1850) of cholera mortality in London during the 1848-49 epidemic.

By John Snow, M.D.

Part 1: (29 November 1851): 559-562

Athough the more severe cases of common English cholera cannot always be distinguished from the malady called Asiatic cholera, yet hardly any one doubts the distinct nature of these diseases, or that the latter was a stranger to Europe prior to the year 1830. A careful consideration of Asiatic cholera shows clearly enough that it is propagated by human intercourse. It has proceeded in various directions along the great channels of intercommunication, never progressing faster than people travel, and generally much more slowly. In extending to an island or a fresh continent, it always makes its first appearance at a seaport, and it never attacks the crew of a ship from a healthy port that is approaching an infected country, till their actual arrival. Many instances have occurred in which quarantine or cordons sanitaires have protected places from the cholera, either altogether, or for a time; and the most conclusive part of the evidence, is the number of instances in which the malady has been introduced into healthy localities by persons who have been taken ill after their arrival from places where cholera prevailed. Dr. Bryson related several instances of this kind in the paper that he read before this Society, and a number more might be now related did the time permit: indeed, the cases in which the progress of cholera can be traced in this manner are the rule rather than the exception, and are, at all events far too numerous to be set down as mere coincidences. It may be remarked, also, that coincidences of this sort are not found to obtain in rheumatism, ague, or indeed in any but epidemic diseases, the whole of which I look upon as communicable from one patient to another, this communication being probably the real feature of distinction between epidemic and other diseases.

Another circumstance strongly confirmatory of the communication of cholera, is the direct relation which exists between the number of the population and the duration of the disease in different towns and villages. The accompanying figures were compiled by me from Dr. W. Merriman's valuable table of cholera in England in 1832* (*Transactions of Royal Medical and Chirurgical Society, 1844): --

It will be seen, that 52 places are enumerated in which the cholera continued less than 50 days, and that the average population of these places was 6,624; that there are 43 places specified in which the disease lasted 50 days, but less than 100, the average population of these places being nearly twice as great as that of the former; while in the remaining 34 towns, in which the cholera continued for 100 days and upwards, the average population was very much greater still, being 38,000 or 78,000, according as London is omitted from or included in the list. I believe that the same rule has obtained during the recent epidemic, but I have no precise information on the point. It is hardly necessary to remark, that if the cholera cases were not connected one with another, there would be no reason why the few cases which happen in a village should not be scattered over as long a period as the thousands which occur in a great metropolis.

I shall perhaps be thought singular in asserting, that there is no evidence opposed to the propagation of cholera by its communication from individual to individual, or in favour of any other origin of the disease. The chief facts which are believed to be opposed to the extension of cholera by communication are the following: That many persons are placed in close relation with the sick, nurse them, and wait upon them, and sometimes even sleep in the same bed, without becoming infected with the malady; that quarantine and cordons sanitaires often fail to arrest its progress; and that persons are often attacked with it who have had no intercourse with the sick or their friends.

These facts are thought to be opposed to the communication of cholera, because it is assumed, that this disease, to be communicated, must extend itself, as the eruptive fevers are believed to do, by means of some emanation given off from the patient into the air; or, if not in that way, then by contact with the patient, or articles of clothing, etc., which have been near him. But, without assuming such hypotheses, the circumstances above mentioned would not in any way oppose the evidence of the communication of cholera. Nearly every one of these facts is equally true of syphilis as of cholera. Persons nurse and wait on syphilitic patients and might even sleep in the same bed with them without contracting the malady; and it is very doubtful, whether quarantine regulations, however strict, would prevent its communication, as they would be evaded. These circumstances are not considered to interfere with the proofs of the contagiousness of syphilis, only because we happen to know the way in which it is communicated and when we shall know equally well the way in which cholera is communicated, I do not doubt that we shall find them equally in applicable to that disease.

A consideration of the pathology of cholera is capable of indicating to us the manner in which the disease is communicated. If it were ushered in by fever or any other general constitutional disorder, then we should be furnished with no clue to the way in which the morbid poison enters the system; but if it commences by a local affection of any particular part, and the system at large only suffers in consequence of the local affection, then it is pretty evident, that the material cause of the disease must have been applied to the part first affected. From all that I have been able to learn of cholera, either by my own observation or that of others, it has appeared, that the illness always commences with the affection of the alimentary canal; and in all the cases that I have seen, the loss of fluid from the stomach and bowels has been sufficient to account for the collapse, when the previous condition of the patient was taken into account, together with the suddenness of the loss, and the circumstance that the process of absorption appears to be suspended. Certain fatal cases of cholera without evacuations have occurred; but, whenever there has been an examination, of the body in such cases, the excretions peculiar to cholera have been found in the bowels. It appears, indeed, that the cholera poison never enters the circulation, and that the blood does not become contaminated in this disease, except when congestion of the kidneys follows as a secondary affection. The irritation of the bowels accounts for the cramps; and the loss of the water and saline constituents of the blood is the cause of the collapse and the symptoms of [559/560] asphyxia. The careful analyses of the blood by Dr. Garrod have confirmed the fact, that its solid constituents are relatively much increased by the loss of water. On this account, it becomes so thick that it circulates with difficulty through the capillaries of the lungs, while the diminished quantity of salts renders it still further unfitted to undergo the usual changes in respiration. The injection of a weak saline solution into the veins of cholera patients in the state of collapse has often been attended with the most surprising effects of a temporary nature, at once restoring the patent, who the minute before was nearly dead, to a state of apparent health and strength. It was justly remarked by Dr. Budd, in a clinical lecture delivered at King's College Hospital, that, if the patient's symptoms depended on a poison circulating in the blood, they could not be removed by the injection of a simple saline solution. The saline solution merely restores the water which has become deficient, and supplies salts analogous to those which have been lost.

If the poison which communicates cholera from person to person does not enter the blood, it is evident that it must multiply itself on the surface of the alimentary canal, and must be contained in the evacuations from the stomach and bowels. The proofs that the cholera poison is contained in these discharges and that the disease is communicated by their being accidentally swallowed, are of a general as well as a particular kind.

It has been constantly observed, that the want of personal cleanliness aided very much the propagation of cholera, although no explanation could be given of the circumstance; it is very evident, however, that without habits of strict cleanliness persons waiting on the sick must get their hands soiled with the cholera discharges, and must unknowingly contaminate the provisions they handle, in eating their own food or preparing that of others. The sudden discharge of the evacuations, which often soil the clothing or bed linen, and the little colour or odour they possess, very much increase the liability to their being swallowed in this way, and under some circumstances render it almost certain. For instance, when a large family, or more than one family are crowded into a single room, and when the same persons have to attend to the patient, and also to prepare and serve the meals for the rest of the inmates, without the materials for washing the hands, even if the inclination should exist, it is next to impossible that the provisions should be eaten without being contaminated with the peculiar discharges of the patient; and these are the circumstances under which the disease is found most frequently to spread among the inmates of a room. Mr. Baker, of Staines, who attended 260 cases of cholera and diarrhea in the late epidemic, chiefly among the poor, informed me in a letter, with which he favoured me in December, 1849, that "where the patients passed their stools involuntarily the disease evidently spread." Deficiency of light is a great obstacle to cleanliness, as it prevents dirt from being seen, and it must aid very much the contamination of the food with the cholera evacuations.

The assistance which crowding lends to the spread of cholera could be explained on the hypothesis of effluvia or miasmata given off from the patient into the surrounding air; but the extension of the disease from want of cleanliness, deficiency of water, and deficiency of light, cannot be explained on such a hypothesis. The non-communication of cholera in cleanly families, where the hand-basin and the towel are in constant use and where the apartments for cooking and eating are distinct from the sick-room; and also its non-communication, as a general rule, to medical men and other visitors of the sick belonging to the educated classes of society, are fully explained on the doctrine here laid down, although these circumstances are inexplicable on the supposition of its spread by means of effluvia. Its fearful extension in certain pauper asylums for children and lunatics is also clearly accounted for, together with its non-liability to spread in more commodious and better regulated establishments.

The great fatality of cholera among all the mining populations of this kingdom has been very remarkable in both the epidemics of that disease. The chief reasons of this are as follow:--The miners generally remain eight hours in the pits, and take food with them, which they eat whilst at work. There are neither privies, hand-basins, nor towels in the mines; and when a case of cholera occurs in a pit, the hands of the workmen, in the dark subterranean passages, can hardly fail to become soiled with the discharges. Should we have a return of the cholera, I believe that many thousands of lives might be saved by dividing the time of labour into two periods of four hours, dissuading the workmen from taking food into the mines and enjoining them to wash their hands on going home before taking any food. There are other causes to be afterwards mentioned which contribute to the extension of cholera in several of the mining districts, viz., the contamination of the wells and brooks with the evacuations of the people.

It can hardly be anticipated, from the nature of the subject, that we should be able to obtain distinct evidence of the cholera evacuations having been taken with the food. The following cases, perhaps, afford as decisive proof of this variety of communication of cholera as can be expected. In the beginning of last year, a letter appeared in the Provincial Medical and Surgical Journal, from Mr. John C. Bloxam, in the Isle of Wight, being an answer to the inquiry on cholera by Mr. Hunt. Among other interesting information, Mr. Bloxam stated, that the only cases of cholera that occurred in the village of Carisbrook, happened in persons who ate of some stale cow-heels, which had been the property of a man who died in Newport, after a short and violent attack of cholera. Mr. Bloxam kindly made additional personal inquiries into the case, in consequence of questions I put to him, and the following is a summary of the information contained in his letter:-–

The man from whose house the cow-heels were sent for sale died on Monday, the 20th of August. It was the custom in the house to boil these articles on Monday, Wednesday, and Friday; and the cow-heels under consideration were taken to Carisbrook, which is a mile from Newport ready boiled, on Tuesday, the 21st. Eleven persons in all partook of this food, seven of whom ate it without any additional cooking. Six of these were taken ill within twenty-four hours after eating it, five of whom died, and one recovered. The seventh individual, a child, who ate but a small quantity of the cow-heels, was unaffected by it. Four persons partook of the food after additional cooking. In one case the cow-heels were fried, and the person who ate them was taken ill of cholera within twenty-four ours afterwards, and died. Some of the food was made into broth, of which three persons partook while it was warm; two of then remained well, but the third person partook again of the broth next day, when cold, and, within twenty-fours [twenty-four hours] after this latter meal, she was taken ill with cholera, of which she died. It may be proper to mention, although it is no unusual circumstance for animal food to be eaten in hot weather when not quite fresh, that some of the persons perceived the cow-heels to be not so fresh as they ought to have been at the time they were eaten, and part of them had to be thrown away a day or two afterwards, in consequence of being quite putrid.

A man living in West-street, Soho, who kept a horse and cart, was employed, in the beginning of September, 1849, to remove some furniture from a house in Lambeth. The furniture had been the property of a woman who died of cholera, and had just been buried. The bedding and night-chair were left just as they were when the patient died. This man was taken with cholera during the night, within thirty-six hours after removing the furniture and other effects and he died of the attack. I saw him with Mr. Marshall, of Greek-street, and we both remarked that his hands were very dirty, and had apparently not been washed for some days.

If the views here explained be correct it is evident that the cholera poison may often be conveyed to a distance with provisions, as in the instance of the cow-heels above-mentioned, when there is no evidence of personal intercourse. There is also another very important medium for transmitting the cholera poison from the sick to the healthy without immediate intercourse. It is the water which people drink and in this case the proofs are often of a more direct and decisive nature.

The deficiency of water had often been spoken of, but the quality of the water had hardly ever been publicly mentioned as contributing to the increase of cholera till August 1849, when Dr. Lloyd related to the South London Medical Society some occurrences that had taken place in Rotherhithe, and a pamphlet of mine, containing other instances, and some reasoning on the subject, appeared as the same time. Mr. John Grant, Surveyor to the Commissioners of Sewers for Surrey and Kent, also drew up a report in the same month, respecting the contamination of a well, in a [560/561] court in Thomas-street, Horsleydown; and attention having been strongly directed to the matter, several other instances of the connexion between violent outbreaks of cholera and the contamination of the drinking water were related.

One of the most fatal instances of communication of cholera by means of water, is that which occurred at Albion- terrace, Wandsworth-road--a row of seventeen houses, most of them detached a few feet from each other, and constituting the genteel suburban dwellings of a number of professional and tradespeople. All the houses were supplied with water on a uniform plan, from a spring in the neighbourhood, the water being conducted into a tank placed behind each house, from which it was pumped into the kitchen when required. The tanks were all connected together by pipes, and the surplus water flowed away into a drain, which received the contents of the house drains and cesspools. The various drains and pipes were so constructed that the water was liable to become tainted, and it had been occasionally complained of previously; but during a storm of rain on July 26th, the chief drain burst, and its contents became mixed with the water in the tanks. I had an opportunity of finding afterwards in the water, the stones and husks of currants and grapes, and various other substances which had gone through the alimentary canal. The more gross materials, however, settled to the bottom of the tanks, and the water pumped up was not so bad as to excite suspicion or attract much attention except in two or three of the houses.

"The first case of cholera occurred at No. 13, on July 28, (two days after the bursting of the drain,) in a lady who had had premonitory symptoms for three or four days. It was fatal in fourteen hours. There was an accumulation of rubbish in the cellar of this house, which was said to be offensive by the person who removed it; but the proprietor of the house denied this. A lady at No. 8 was attacked with choleraic diarrhœa on July 30; she recovered. On August 1, a lady, aged 81, at No. 6, who had had some diarrhœa eight or ten days before, which had yielded to her own treatment, was attacked with cholera ; she died on the 4th, with congestion of the brain. Diarrhœa commenced on August 1, in a lady, aged 60, at No. 3; collapse took place on the 5,th, and death on the 6th. On August 3 there were three or four cases in different parts of the row of houses, and two of them terminated fatally on the same day. The attacks were numerous during the following three or four days, and after that time they diminished in number. More than half the inhabitants of the part of the terrace in which the cholera prevailed were attacked with it, and upwards of half the cases were fatal. The deaths occurred as follow; but as some of the patients lingered a few days, and died in the consecutive fever, the deaths were less closely grouped than the seizures. There was 1 death on July 28, 2 on August 3, 4 on the 4th, 2 on the 6th, 2 on the 7th, 4 on the 8th, 3 on the 9th, 1 on the 11th, and 1 on the 13th. These make 20 fatal cases; and there were 4 or 5 deaths besides amongst those who were attacked after flying from the place." The fatal cases were distributed over ten of the seventeen houses, and cases occurred also in the other seven houses, with the exception of one or two that were empty, or nearly so. In short, the cholera extended to all the houses supplied by the contaminated water, and to no others; for there were hardly any cases in the immediate neighbourhood at the time.

There are no data for showing how the disease was communicated to the first patient, at No. 13, on July 28; but it was two or three days afterwards, when the evacuations from this patient must have entered the drains having a communication with the water supplied to all the houses, that other persons were attacked, and in two days more the disease prevailed to an alarming extent.

A similar instance of communication of cholera through the water occurred nearly at the same time "in Thomas-street, Horsleydown, where there are two courts close together, consisting of a number of small houses or cottages inhabited by poor people. The houses occupy one side of each court or alley, the south side of Trusscott's-court, and the north side of the other, which is called Surrey-buildings, being placed back to back, with an intervening space, divided into small back areas, in which are situated the privies of both the courts, communicating with the same drain; and there is an open sewer which passes the further end of both the courts. Now, in Surrey-buildings, the cholera committed fearful devastation, whilst in the adjoining court there was but one fatal case, and another that ended in recovery. In the former court the slops of dirty water, poured down by the inhabitants into a channel in front of the houses, got into the well from which they obtained their water, this being the only difference that Mr. Grant, the Assistant-Surveyor for the Commissioners of Sewers, could find between the circumstances of the two courts, as he stated in his report to the Commissioners. The well in question was supplied from the pipes of the South London Water Works, and was covered in on a level with the adjoining ground; and the inhabitants obtained the water by a pump placed over the well. The channel mentioned above commenced close by the pump. Owing to something being out of order, the water for some time past occasionally burst out at the top of the well, and overflowed into the gutter or channel, afterwards flowing back again mixed with the impurities; and crevices were left in the ground or pavement, allowing part of the contents of the gutter to flow at all times into the well, and when it was afterwards emptied, a large quantity of black and highly offensive deposit was found it.

"The first case of cholera in this court occurred on July 20th, in a little girl, who had been labouring under diarrhœa for four days. This case ended favourably. On the 21st July, the next day, an elderly female was attacked with the disease, and was in a state of collapse at ten o'clock the same night. Mr. Vinen, of Tooley-street, who attended these cases, states that the evacuations were passed into the beds, and that the water in which the foul linen would be washed would inevitably he emptied into the channel mentioned above. Mr. Russell, of Thornton-street, Horsleydown, who attended many of the subsequent cases in the court, and who, along with another medical gentleman, was the first to call the attention of the authorities to the state of the well, says that such water was invariably emptied there, and the people admit the circumstance. About a week after the above two cases commenced, a number of patients were taken ill nearly together: four on Saturday, July 28th, seven or eight on the 29th, and several on the following day. Eleven of the cases were fatal. The deaths occurred in seven out of the fourteen small houses in the court.

"The two first cases on the 20th and 21st may be considered to represent about the average amount of cases for the neighbourhood, there having been just that number in the adjoining court about the same time. But, in a few days, when the dejections of these patients must have become mixed with the water the people drank, a number of additional cases commenced nearly together."* (*The passages in the above account, included within inverted commas [quotation marks], are quoted from a pamphlet, by the Author, "On the Communication of Cholera.")

The following instances were made known by Dr. Lloyd:--In Silver-street, Rotherhithe, there were 80 cases and 38 deaths in the course of a fortnight, early in July, 1849, at a time when there was very little cholera in any other part of Rotherhithe. The contents of all the privies in this street ran into a drain which had once had a communication with the Thames; and the people got their supply of water from a well situated very near the end of the drain, with the contents of which the water got contaminated. Dr. Lloyd informed me that the fetid water from the drain could be seen dribbling through the side of the well, above the surface of the water. Among other sanitary measures recommended by Dr. Lloyd, was the filling up of the well; and the cholera ceased in Silver-street as soon as the people gave over using the water. Another instance alluded to by Dr. Lloyd was Charlotte-place, in Rotherhithe, consisting of seven houses, the inhabitants of which, excepting those of one house, obtained their water from a ditch communicating with the Thames, and receiving the contents of the privies of all the seven houses. In these houses there were 25 cases of cholera, and 14 deaths; one of the houses had a pump railed off to which the inhabitants of the other houses had no access and there was but one case in that house.† (†See Med. Gaz., 1849, vol. II., p. 429.)

The following instance, as well as some others of a similar kind, is related in the Report on Cholera by the General Board of Health:-–

"In Manchester, a sudden and violent outbreak of cholera occurred in Hope-street, Salford. The inhabitants used water from a particular pump-well. This well had been repaired, and a sewer which passes within nine inches of the [561/562] edge of it became accidentally stopped up, and leaked into the well. The inhabitants. of 30 houses used the water from this well; among them there occurred 19 cases of diarrhœa, 26 cases of cholera, and 25 deaths. The inhabitants of 60 houses in the same immediate neighbourhood used other water; among these there occurred 11 cases of diarrrhœa, but not a single case of cholera, nor one death. It is remarkable, that, in this instance, out of the 26 persons attacked with cholera, the whole perished except one."-–P. 62.

Dr. Thomas King Chambers informed me, that at Ilford, in Essex, in the summer of 1849, the cholera prevailed very severely in a row of houses a little way from the main part of the town. It had visited every house in the row but one. The refuse which overflowed from the privies and a pigsty could be seen running into the well over the surface of the ground, and the water was very fetid; yet it was used by the people in all the houses except that which had escaped cholera. That house was inhabited by a woman who took linen to wash, and she, finding that the water gave the linen an offensive smell, paid a person to fetch water for her from the pump in the town, and this water she used for culinary purposes, as well as for washing.

The time does not permit of my relating any more of the numerous instances in which severe outbreaks of cholera have been connected with adulteration of the water with the contents of drains and cesspools; and this is the less to be regretted, as the influence of this kind of water over the increase of cholera is now generally admitted.

In the seventh notification of the General Board of Health, on September 18, 1849, soon after attention had been first prominently drawn to this matter, the following passage occurs:-–"The ascertained fact, that the use of vitiated water acts as a poison on the stomach and bowels, producing sickness, diarrhœa, and other symptoms resembling those of cholera, has recently received melancholy confirmation in numerous instances."

Now, in these instances, the disease induced is admitted to have been actual cholera in the same notification, and in the subsequent report of the Board, and there is no evidence to show that vitiated water generally acts as a poison; on the contrary, in many of the instances in which these outbreaks of cholera occurred, the people had been drinking the same vitiated water since the cholera of 1832. However repulsive to the feelings the swallowing of human excrement may be, it does not appear to be very injurious so long as it comes from healthy persons, but when it proceeds from cholera patients, and probably patients with some other maladies, it is a means of communicating disease.

Part 2: (13 December 1851): 610-612

Although, as I have observed, the influence of vitiated water in aiding the spread of cholera is now generally admitted, it must be stated that it is not usually understood to act in the way I have explained; but the contaminated water is thought by many to predispose persons, so that an unknown cause of cholera may act upon them in some inexplicable way. The manner in which these outbreaks occur, when caused by the contamination of a local supply of water, shows, however, that it does not act by merely inducing a predisposition. The water in many of the instances had been contaminated for months or even years, when a case or two of cholera occurring amongst the people on the spot, whose evacuations entered the water through the drains or otherwise, in a day or two afterwards there was a simultaneous outbreak of the malady amongst a number of the persons using the water; whereas, if the water had merely caused a predisposition, and was not acting as the exciting cause, the cases of cholera, however numerous in the locality, might be expected to be distributed over the period that the disease prevailed in the town or district in which the locality was situated. In a review in the Medical Gazette, in 1849, the remark was made, that as the communication of cholera to the first case in Albion-terrace could not be traced, and was of course not attributable to the water, which did not yet contain the cholera evacuations, the same cause which would produce that case would produce others in the immediate vicinity. This must be admitted to be possible; and in the same way, if a fire had taken place from some unknown cause in No. 13, and the whole row had been burned down, it must also be admitted that a fire might possibly have originated from the same unknown cause in all the other houses about the same time, and that the burning of the one had no connexion with that of the others. No one, however, would believe this to have been the case.

Besides the local outbreaks already alluded to, it can be shown, that the cholera was often communicated through the water, on a more extensive scale, by means of the sewers which empty themselves into various rivers, from which the population of many towns derive their supply of water. In several towns of this country, among which are Birmingham, Leicester, Bath, and Cheltenham, there were only a few cases of cholera, either in 1832 or 1849, and those chiefly in persons who had arrived from other places in which the cholera was prevailing, or among the immediate attendants of these patients. Now, all these towns were supplied with water from sources quite uncontaminated with the contents of sewers. In some towns so circumstanced, there has been a good deal of cholera, but then it was confined to the poor, and to particular localities in the towns; but on the other hand, in all those towns in which the malady extended generally, and was not confined to the poor and dirty, this connexion between the sewers and drinking-water existed. A great part of London was in this condition in both epidemics; Exeter was so in 1832, and Hull in 1849. The difference between the two epidemics in Exeter and Hull, in connexion with an altered supply of water, is very remarkable. In 1832, the people of Exeter were supplied with water by water-carriers, who obtained it from two mill-streams diverted from the river; and one of the chief sewers of the town emptied into a branch of the river which divided into the two mill-streams. Cholera commenced with a woman and child who had just arrived from Plymouth, where the former had been nursing another child that had died of the same disease. It soon became very prevalent and severe for the size of the town. There were 1135 cases, and 343 deaths.* Subsequently to 1832, Exeter has been supplied by waterworks, with water derived from the river Exe, at a point two miles above the town and more than that distance above the influence of the tide. In 1849, there were only about 20 cases of cholera in Exeter, nearly half of which occurred in strangers coming into the town, and dying within two or three days after their arrival. (*See "History of the Cholera In Exeter in 1832." by Dr. Shapter, to whose kindness the writer is indebted for additional information.)

In 1832 Hull was scantily supplied with water, conveyed in pipes from some springs situated three miles from the town; in the epidemic of that year the cholera was confined almost exclusively to the poor, and the deaths amounted to 300. Between that time and 1849, Hull, besides an improved system of drainage, obtained a more abundant supply of water. The water-works, however, are situated on the river Hull two miles and three quarters from its confluence with the Humber. About half the sewage of the town is delivered into the river Hull, and the tide flows up this river for many miles past the waterworks, carrying with it the filth from the sewers. In the late epidemic the deaths from cholera and diarrhœa in Hull amounted to nearly 3000, and occurred among all classes of the community.

In London the cholera was most prevalent during both epidemics in those districts supplied with water vitiated by the contents of sewers and cesspools, and indeed it generally bore an exact relation to the amount of vitiation. The map from the second Report on the Health of Towns, which is suspended in the room, shows the districts of the metropolis supplied by the different Water Companies; and the other map, from Mr. Grainger's Appendix to the Report of the Board of Health on Cholera, is coloured to show the relative prevalence of the late epidemic in different parts of London. A large district on the north of the Thames is supplied with the New River water, which is not contaminated by the sewers; another district on the same side of the river is supplied by the East London Water Works Company, with water obtained from the Lea, above the influence of the tide, and nearly, if not altogether, free from contamination. These districts are not much tinted with the blue of cholera in Mr. Grainger's map, except in particular spots in which there was generally a local supply of contaminated water, as, for instance, in the neighbourhood of Bridge-street, Blackfriars, where many of the inhabitants obtained water for drinking from St. Bride's pump, which was afterwards closed in consequence of its being ascertained that the well had a communication with a sewer which emptied into the Fleet ditch; and in the vicinity of Shoreditch and at Hackney, where Dr. Gavin found the contents of the privies overflowing or percolating into the wells in certain courts and allies. The north-west districts of the metropolis are supplied with water by the West Middlesex and Grand Junction Water Companies, who obtain the water from the Thames, near Hammersmith and Brentford, where the river is in a great measure free from sewage at particular times of the tide, and the water is also purified by subsidence in large reservoirs. The districts so supplied were not severely visited by cholera.

The district supplied by the Chelsea water-works, was not severely visited by cholera during the late epidemic, as appears by the cholera map, except in particular spots where contaminated water was used, as in the neighbourhood of Duke-street, Chelsea, where many of the people obtained water by dipping a pail into the Thames. Now, the Chelsea Company derive their supply of water from the Thames at Chelsea, where it is very foul; but having till lately to supply the Court and a great part of the nobility, they have large and expensive filters, and also very capacious settling reservoirs, in which the water is kept for a considerable time before its distribution. Dr. Hassall found the Chelsea Company's water to contain much less organic matter than that of the Companies supplying the districts on the south of the Thames; and he found it to be free from the hairs of the down of wheat, yellow ochreous substance, (believed to be partially digested muscular fibre,) and other substances which had passed through the alimentary canal, and were found in the Vauxhall and Lambeth Companies' water.† (†A Microscopic Examination of the Water supplied to the Inhabitants of London.)

The districts of London, on the south side of the river, are [610/611] supplied with water obtained from the Thames near the Hungerford Suspension Bridge, and at Vauxhall, by the Lambeth, the Vauxhall, and the South London Companies. The water is very imperfectly filtered and has little or no opportunity to subside; and according to the evidence of Dr. Hassall, mentioned above, it contains a great deal of excrementitous matter. The cholera was very much more severe on the south side of the Thames than on the north, as appears by the map. There were other causes for this besides the water supplied by the Companies. The wells in this part of the town are very shallow, and are often vitiated by the contents of the cesspools, which percolate through the ground; and a yet more important cause of the great prevalence and fatality of cholera was the existence of certain tidal ditches in Bermondsey and Rotherhite, the places in which the mortality was greater than in any other part of the Metropolis in the late epidemic. These ditches were the direct receptacles of the excrementitious matters of a large population, and furnished at the same time the only supply of water that could be obtained by a great number of the inhabitants. I was furnished by Mr. Grant with the result of a house to house visitation in Jacob's Island, which is surrounded by one of these ditches, and it shows that the mortality from cholera was much higher among the people who had no supply of water except from the ditches, than among those who had access to the pipe-water of the Company.

In the epidemic of 1832, the part of this Metropolis most severely visited by cholera was the Borough of Southwark, in which ninety-seven persons in each 10,000 of the population were carried off, being nearly three times the proportion of those that died in the rest of London. Now, the Borough at that time was supplied by the Southwark Water Works with Thames water obtained at London-bridge, and sent direct to the houses without the intervention of any reservoir.

The communication of cholera by means of the water is well illustrated by the instance of Moscow, which was severely visited by that disease in 1830, but much less severely in the second epidemic. Subsequently to 1830 the greater part of the town, which is situated to the north of the Moscow river, obtained a supply of excellent water conducted in pipes from springs at a distance; and the cholera in 1847 was chiefly confined to those parts of the town which lie to the south of the river, to which the new supply of water did not extend, and where the people had still only impure river water to drink.* (*Report of Swedish Commissioners, quoted in the Second Report of the Metropolitan Sanitary Commission. 1848.

The Table ([copied and suspended in the room]) from the Weekly Report of the Registrar-General of January 12, 1850, shows the mortality from cholera in the different districts of London supplied by the various Water Companies; and if the purification of the Chelsea water, and certain local contaminations of the water before mentioned be taken into account, the mortality will be found to bear a very close relation to the absence or presence of connexion between the sewers and the water supplied. It also appears from the same table that the average mortality from all causes in a series of years bears a relation to the quality of the drinking water. There is great reason to believe that typhoid fever and some other epidemic diseases are communicated occasionally through the drinking water; and there are a great number of facts in the history of the Plague that have led me to believe that it is communicated in exactly the same way as cholera. There are also many circumstances which render it probable that the cause of one disease not epidemic and communicable from person to person, but endemic viz., ague--often exists in the water of marshy districts, and is acquired by drinking the water; but there is not space to enter on these subjects at present.† († Mr. Wm. Blower, surgeon of Bedford, speaking of Wooton, near Bedford, says, "A few wells have been dug lately, and good water has been obtained, and there is every probability, that if the water pits were filled up, and more wells dug, and the draining completed, that sporadic typhus and ague which have so long infested this village, and occasioned so much distress and expense, might be entirely eradicated. A respectable farmer informed me that, in the neighbourhood of Houghton, a few years ago, his was the only family that used well water, and almost the only one that escaped ague."--General Report of Poor-law Commissioners on the Sanitary Condition of Great Britain, 8vo. 1842. P. 66.

Mr. Grainger also quotes some instances, at page 94 of his recent Appendix to the Cholera Report, in which a number of persons contracted intermittent fever by drinking marsh water, while others, exposed to the same atmosphere, who did not drink the water, altogether escaped.)

The large public institutions of London, in which the inmates are shut up from the rest of the community, showed the influence of the water, or the absence of that influence, in a remarkable manner during the late epidemic of cholera. Bethlem Hospital and the Queen's Prison are both supplied with water from deep wells on the premises, and, although situated on the south of the Thames, in a district in which the cholera was very fatal, there was not a death from that disease in Bethlem Hospital, with a population of more than 400, and only one death in the Queen's Prison, with a population of 300 and upwards. In Milbank Prison, on the contrary, the cholera was very prevalent until the greater number of the prisoners were sent away. It was considerably worse, in fact, than among the population outside in the same neighbourhood. There were 113 cases and 48 deaths; the deaths amounting to 4.3 per cent. of the average number of prisoners. The water used in the Milbank Prison was obtained from the Thames at the spot: it was filtered, indeed, through sand and charcoal, but not kept for a while in large reservoirs like that sent from the Chelsea Water-works to the rest of Pimlico and Westminster. In Tothillfields Prison, supplied by the waterworks just mentioned, there were 13 deaths from cholera among 800 prisoners, but in all the other prisons on the north of the Thames which are supplied with water into which the sewage cannot enter, there was but one death from cholera; that death took place in Newgate.

The first cases of cholera which occurred in London in the autumn of 1848 are particularly interesting with reference to the influence of the water of the Thames. According to the valuable Report of Dr. Parkes on the subject, subsequently corrected by him in one or two particulars, in consequence of some information which I received from Mr. Russell, surgeon, of Horsleydown, the first case of cholera in London (when the disease was introduced into this country from Hamburg, the greatest commercial town on the continent of Europe, as it had been just seventeen years before) occurred on September 22nd, in a seaman named John Harnold, newly arrived by the Elbe steamer. It is, indeed, said that cases of cholera occurred in London prior to this; and Dr. Copland mentioned one in the Medical Gazette as having happened on July 11th, in a man who had been employed on board of a steam-vessel from St. Petersburgh, where the pestilence was then prevailing. But, looking on the case of John Harnold as the first, then the next case occurred in the same room, on September 30th-–eight days afterwards-–in the person of a workman, named Blenkinsopp. These cases occurred in New-lane, Gainsford-street, Horsleydown, close to the Thames. In the evening of the day on which the second case occurred in Horsleydown, a man was taken ill in Lower Fore-street, Lambeth, and died on the following morning. At the same time that this case occurred in Lambeth, the first of a series of cases occurred in White Hart-court, Duke-street, Chelsea, near the river. A day or two afterwards, there was a case at 3, Harp-court, Fleet-street. The next case occurred on October 2nd, on board the hulk Justitia, lying off Woolwich; and the next to this in Lower Fore-street, Lambeth, three doors from where a previous case had occurred. The first thirteen cases were all situated in the localities just mentioned; and on October 5th there were two cases in Spitalfields.

Now, the people in Lower Fore-street, Lambeth, obtained their water by dipping a pail into the Thames, there being no other supply in the street. In White Hart-court, Chelsea, the inhabitants obtained water for all purposes in a similar way. A well was afterwards sunk in the court; but at the time these cases occurred the people had no other means of obtaining water, as I ascertained by inquiry on the spot. The inhabitants of Harp-court, Fleet-street, were in the habit, at that time of procuring water from St. Bride's pump, which was afterwards closed on the representation of Mr. Hutchinson, surgeon, of Farringdon-street, in consequence of its having been found that the well had a communication with the Fleet-ditch sewer, up which the tide flows from the Thames. I was informed by Dr. Dabbs, that the hulk Justitia was supplied with spring water from the Woolwich Arsenal; but it is not improbable that water was occasionally taken from the Thames alongside, as was constantly the practice in some of the other hulks, and amongst the shipping generally.

It must no doubt seem very unlikely to many that the materies morbi of a disease should pass for a distance of two or three miles through the water; but the propagation of [611/612] plants and the lower forms of animals by seeds and ova which can be transported to a distance would appear equally improbable, were it propounded for the first time. Analogy leads to the belief that, however minute the particles which propagate cholera, they must yet have a definite structure, (probably that of a microscopic cell), and must therefore not be capable of dilution, so as to be rendered inert.

In the autumn of 1849, Drs. Brittan and Swayne, of Bristol, considered that they had discovered the cause of cholera in a minute fungus; and Dr. Wm. Budd, of the same city, met with the supposed fungus in various specimens of water used as drink, in places where the cholera was very prevalent. It was, perhaps, too much to expect, that we should obtain a knowledge of cholera more exact than that which we possess of syphilis, small-pox, and other better known diseases; and the supposed fungi were resolved into other things. As many of these, however, were particles of bran and other matters which had passed through human intestines, the labours of these gentlemen confirm the fact of the water in various places being a medium of communication between the alimentary canals of cholera patients and those of other people.

In one of the Registration Reports, in the beginning of last year, Mr. Farr pointed out a remarkable connexion between the prevalence of the cholera of 1849 and the temperature of the Thames. The probable reason of this connexion is, that the cholera poison does not so well retain its properties unimpaired in water below 60° Fahr. as at warmer temperatures. Mr. Farr appeared to attribute the influence of temperature to the increased amount of vapour and effluvia given off from the surface of the river; but this would not explain the influence of the water on those who drink it.

It may be here remarked, that it would be unreasonable to expect to trace every case of cholera, either through the water, or by contamination of the food; more especially as it is sufficiently probable that the disease may be communicated by cases which proceed no further than preliminary diarrhœa. If the view here given be found to explain more of the progress of cholera the more it is inquired into, it must be held to account for the cases which cannot be traced, in the same way that generation accounts for the existence of plants and animals under circumstances in which we cannot always trace their parentage.

With regard to preventive measures, I entirely agree with the Registrar-General, that "internal sanitary arrangements, and not quarantine or sanitary lines, are the safe- guards of nations." For I believe that quarantine would often be evaded, and is altogether unnecessary. The presumed sanitary measures however, should have a particular reference to the mode of communication of cholera, otherwise they may sometimes be prejudicial instead of advantageous. I have given one instance in the case of Hull, where the malady was nearly ten times as fatal in the late as in the former epidemic, on account of a more plentiful supply of water having been obtained without reference to its quality. In London, the late epidemic was three times as fatal as that of 1832. This was, in my opinion, partly owing to the manifestoes of the General Board of health, which were understood to imply that the cholera was not communicable or catching in any way; and these documents had an immense circulation, by being copied into the newspapers. The effect was also due to presumed sanitary measures employed both in the interval of the two epidemics and during the late one. In the interval a great number of cesspools had been abolished, and a much larger amount of fæces became daily sent into the Thames, whilst a great portion of the people had still to drink the water; and during the epidemic itself, the flushing of the sewers increased the mischief in two ways: first, by driving the cholera evacuations into the river before there was time for the poison to be rendered inert by decomposition; and second, by making increased calls on the various companies for water to flush the sewers with, so that the water which they sent to their customers remained for a shorter time in the reservoirs before being distributed. It should be remarked, also, that the contents of the sewers were driven into the Thames by the flushing, at low water, and remained flowing up the stream for four or five hours afterwards.

The sanitary measures required for the prevention of cholera, according to the views here explained, suggest themselves at once. They are as follow:–-

1. The entire disuse of water into which sewers flow, or which is navigated by persons living in boats, or which is in any other way contaminated by the contents of drains or cesspools.

2. An extended use of hand-basins and towels among the poor, together with sufficient water always in readiness.

3. Strict cleanliness in every one about the patient, or the dead body; and especial care in all such persons to wash their hands before touching food.

4. The separation of the healthy from the sick, and their removal to another abode, when they have no place but the sick room in which to prepare and take their meals.

5. The immersion of all soiled linen in water, until it can be scalded and washed; for if it should become dry, the feces might be wafted about in the form of dust and so be swallowed by any one who should come near the linen.

In the way just indicated, it is probable that cholera may be occasionally communicated for a short distance through the air; and when small-pox and other diseases are communicated through the air, it is most likely by organised particles, which are wafted like the seeds of plants and the ova of some animals, and not by anything in the form of gas or vapour. Indeed there are neither facts nor analogy to show that any kind of epidemic disease whatever can be caused by the air, or even influenced by it, otherwise than indirectly. Epidemics have been attributed to the state of the atmosphere since the time of Hippocrates, and the antiquity of the belief causes it to be received as an indisputable axiom, although our better knowledge of the nature of the air, and of gaseous bodies in general, is capable of entirely disproving it. But the facts which disprove the atmospheric theory of diseases are often pressed into its service, and so handled as to lend it apparent support.

It is a curious circumstance that the medical men who are most active in advocating the sanitary measures whish, as a general rule, would prevent the communication of cholera, for the most part disbelieve in its communicability, probably because the question had never suggested itself to them, except in the form of infection by means of effluvia, or of contagion by contact. What is still more remarkable is that these gentlemen generally look on the presence of all those circumstances which aid in the communication of cholera, when found in situations where the pestilence prevails, as proofs that it is not communicable. They speak of these circumstances as something which can explain the increased prevalence of the disease without its being communicable, although it has never been explained in this way, even by a hypothesis. One or two hypotheses have indeed been attempted, but have signally failed. One of the most able and experienced authors on cholera writes, for instance, as follows.-–"If we could suppose that certain organic impurities existing in the atmosphere of unhealthy neighbourhoods, passed into the blood through the lungs, so as to follow the circulation and that similar impurities taken into the stomach with articles of food or drink, were likewise absorbed into the blood; if we could, moreover, suppose that the epidemic influence possessed the power of assimilating such organic matter to its own poisonous nature, we should be enabled to include a number of complex phenomena under a hypothesis which would indicate the requisite measures of prevention." The above quotation is from Dr. Sutherland's Appendix to the Report on Cholera; but the latter part of the supposition is quite incapable of being entertained for various reasons, one of which is, that the assumed epidemic influence, in order to be capable of acting in this way, must consist of some material mixed with the atmosphere, and if so, it would diffuse itself through the air, and would also pass along with the air. It could not travel against the wind, or remain in a spot for weeks, without extending to the next parish when the air is moving at the rate of one or two hundred miles a day.

There is much evidence on the subject of this paper which I had not room to bring forward, and many important points connected with it that I have not been able even to allude to; but I trust that I have succeeded in drawing the attention of the Society to the views I have endeavoured to explain, in such a way that they will be induced to consider the question carefully for themselves.*

54, Frith-street, Soho-square.

*This paper was originally read before the Epidemiological Society of London.

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67. "On narcotism by the inhalation of vapours."

Source: Snow, John. London Med. Gazette 48, 19 December 1851, pp. 1053-57 (part 17).

[Part 17]

Action of oxygen in respiration--Nature of asphyxia--Comparison between asphyxia and narcotism--Between narcotism and apoplexy--Cause of the symptoms in apoplexy--Diminished production of carbonic acid, and reduction of temperature under the influence of narcotics--Narcotic effect of cold--Colour of the blood under the influence of chloroform and ether--Irritability of the muscles after death--Effect of chloroform, etc. on this irritability, and on the rigor mortis--Modus operandi of chloroform, etc.

For a length of time after the changes which are effected in the air by respiration were discovered, it was generally believed that the carbonic acid was formed in the lungs, by the union of the oxygen of the air with carbon contained in the blood; and the phenomena of asphyxia were thought to be occasioned by the direct action of some form or combination of carbon which ought to have been excreted. Experiments by Edwards, and others, on the respiration of animals in hydrogen gas, and especially the beautiful experiments of Professor Magnus on the blood, clearly proved, however, what many physiologists had believed from the first,--that the oxygen of the air is absorbed (along with some nitrogen) and circulates with the arterial blood, combining with carbon in the systemic capillary circulation; and thus forming the carbonic acid which is exhaled from the blood in its passage through the lungs. Asphyxia is simply due to the want of oxygen in the arterial blood: for, although there is a little carbonic acid gas present in this blood during the more ordinary forms of asphyxia, yet the same symptoms occur to animals placed in hydrogen or nitrogen gas, although the carbonic acid gas in the blood is then exhaled. The presence of oxygen in the blood seems absolutely necessary to the performance of the animal functions--so necessary that none of them can continue an instant without it. Animals live, it is true, for a short time after they are deprived of air, but a little consideration shows that they live only by virtue of the oxygen which is contained in their bodies, and that when this is consumed life no longer continues. The length of time which animals live after they are deprived of air is in the inverse ration of the activity of their functions, and Dr. W. F. Edwards has shown* that animals of cold blood, as reptiles and fishes, die of asphyxia nearly as quickly as animals of warm blood when they are placed in water deprived of air, and of a temperature of about 100° Fah.

(*De l'Influence des Agens Physiques sur la Vie.)

The increase of heat quickens the changes taking place in the body, as the same author has proved by distinct experiments: the oxygen dissolved in the fluids of the animal is soon appropriated, and life is then extinct. Animals of cold blood can also be quickly killed at the ordinary temperature by the rapid absorption of agents, such as the vapour of ether, which have the undoubted power of arresting oxidation out of the body, and when present in the blood in sufficient quantity, have the effect of preventing the oxygen it contains from any longer entering into combination. The experiments of Dr. Kay† show that venous blood has some power of supporting the functions of the brain, and the irritability of the muscles when injected into the arteries, but this depends on some free oxygen it contains; for the analyses of Magnus have proved that arterial blood is only deprived of part of its oxygen by passing once through the systemic capillaries.

(†The Physiology, Pathology, and Treatment of Asphyxia, p. 193).

The relation between asphyxia and narcotism is this--that in asphyxia there is an absence of oxygen, whilst in narcotism the oxygen is present, but is prevented from acting by the influence of the narcotic. With this close affinity between asphyxia and narcotism, as regards their intimate nature, there is, as might be expected a great similarity in the phenomena of the two conditions. The different parts of the nervous centres lose their power, under the influence of ether and chloroform, in the same order as in asphyxia. The action of the heart continues in asphyxia after the muscles of respiration have ceased to contract, and this is the case under the effects of chloroform, alcohol, ether, and probably all narcotics, when they are absorbed in a gradual and uniform manner. For, as the muscular contractions of a peristaltic character, which are under the influence of the ganglionic system of nerves, can go on with a smaller amount of oxygen than those which are dependent on the cerebrospinal system, so it requires a larger quantity of the narcotic to arrest them. During sudden asphyxia of robust subjects by privation of air, there are generally convulsions after the loss of consciousness, and there is likewise usually an amount of muscular rigidity and contraction approaching to convulsions when insensibility is quickly induced by chloroform or ether, in muscular persons or robust animals. By gradually inducing narcotism these contractions can be avoided, and in like manner, when asphyxia is slowly induced by vitiation of a limited supply of air, convulsions are not induced. The impediment offered to the absorption of oxygen in the lungs during bronchitis is sometimes accompanied by delirium not unlike that caused by a narcotic, and occasionally coma is met with. The state of the fœtus in utero--just able to perform a few languid movements of its limbs--resembles very much the sleep caused by a narcotic. At this time it receives only a limited supply of oxygen at second hand through the placenta; but on being born, no sooner has it taken one or two free inspirations, than it exhibits an amount of activity and strength which would be fatal to the mother did it possess it whilst in the womb.

With all these points of resemblance between narcotism and asphyxia, it might perhaps be asked why a limitation of the supply of air, or in other words a partial asphyxia, might not be resorted to instead of a narcotic to prevent the pain of operations. The answer must probably be sought in the circumstance remarked by all the observers of the phenomena of asphyxia, that the blood becomes arrested at the pulmonary capillaries, when oxygen is no longer admitted into the air cells of the lungs. On this account insensibility cannot be induced by means of asphyxia, without causing congestion of the lungs, and great distress of the respiration.

In a profound state of narcotism the symptoms often exactly resemble those of apoplexy. In both conditions there is a partial suspension of the process of oxidation on which the functions of the brain depend; but this impediment to the natural process of oxidation arises from a different cause in the two cases. In narcotism it is due to the presence of the narcotic substance in the blood, which retards oxidation, as we shall presently see, by a kind of counter affinity for the oxygen: in apoplexy it depends on more or less complete interruption to the circulation of the blood. For the constant action between the oxygen of the arterial blood and the brain, there is obviously required a never-ceasing current of blood; and when this is interrupted in any part of the brain, it matters not whether the circulation be interfered with by pressure arising from effusion, by the occlusion of one or more of the arteries which cuts off part of the supply, or by such an amount of congestion from any cause that the current of the circulation is interrupted. According to these views it ought not to signify whether there is increased or diminished pressure in the cranium, or whether the quantity of blood in the brain is more or less than natural; but if the circulation is interrupted or greatly impeded, there ought to be the symptoms which arise from impeded oxidation. Such indeed is the fact; we meet with the same symptoms in very different physical conditions of the contents of the cranium, and the question of bleeding and the application of other remedies cannot be decided by the cerebral symptoms alone, without the consideration of other particulars.

The circulation through the capillaries of the brain is undoubtedly sometimes retarded under the influence of narcotics; but this is the consequence and not the cause of the impeded functions of the brain. For, as was first pointed out by Professor Alison, the functions of the various organs of the body are accompanied by a force which aids the capillary circulation; and on the function of any organ being interrupted, the circulation through it is retarded, as is seen in the most striking manner in the lungs during asphyxia. There is this further difference also between narcotism and apoplexy, that the narcotic acts directly on all parts of the body as well as on the brain, whilst in apoplexy the remainder of the nervous system and the other organs of the body are only effected in a secondary manner.

In my last communication,* several experiments were detailed which show that the quantity of carbonic acid evolved from the lungs is considerably diminished under the influence of ether and chloroform.

(* See last vol. p. 622 [part 16]).

This circumstance indicates diminished oxidation, for carbonic acid is the chief product of that process in the animal frame, and it bears a pretty close relation to the amount of oxygen consumed. Dr. Prout formerly showed that the quantity of carbonic acid produced in respiration was diminished after drinking alcoholic liquors, and alcohol very much resembles ether and chloroform in chemical constitution and physiological effects. Under the influence of this agent, alcohol, Böcker ascertained, as was noticed before, that the amount of every one of the constituents of the urine is diminished, and phosphoric acid and urea are important products of oxidation.

In some experiments detailed in the first part of these papers,† the temperature of animals was seen to diminish under the continued influence of ether and chloroform.

(†Medical Gazette, vol. xli. p. 850).

This circumstance is also illustrative of the diminished oxidation that is taking place, for the experiments of Dr. W. F. Edwards‡ on animals of various species, at different seasons of the year, show that the consumption of oxygen in respiration always bears a direct proportion to the evolution of animal heat.§

(‡Op. cit.)

(§ The cooling of animals, in Sir B. Brodie's experiments, when the circulation was kept up by artificial respiration, after they were reduced to a state of suspended animation by narcotics, gives support to the above views; allowance being made for the artificial condition of the animals. The other experiments of this eminent physiologist, in which animals were found to cool rapidly under similar circumstances, after removal of the brain, are not at all opposed to the view that animal heat results from the process of respiration, if we reflect that respiration, or oxidation, is essential to all the animal functions, and that the formation of phosphoric acid and urea are probably as much accompanied by the evolution of caloric, as is the formation of carbonic acid.)

Gradual exposure to a lower temperature, as happens in the change of season from summer to winter, alters the constitution of many animals, causing them to consume more oxygen and thus to develop more heat, and bear up against a colder season; but other species, including some mammalia, as well as nearly all reptiles are narcotised by the cold, and fall into a state of torpor in the winter, when the consumption of oxygen is reduced to a minimum. Cold air, or whatever abstracts the heat of the body, so as to make a considerable reduction in its temperature, is a true narcotic, and acts like other narcotics, by diminishing oxidation. Travelers in the arctic regions inform us that the symptoms produced by intense cold are sometimes not to be distinguished from intoxication by alcohol, except by the circumstance that no spirituous liquor can have been obtained. As regards its local effects, cold is probably the narcotic which has been longest known to the human species; for its benumbing effects make themselves felt, in the fingers at least, in most parts of the earth, at some season of the year. The local application of cold closely resembles that of chloroform and many other narcotics, in causing a slight amount of pain before sensibility is altogether abolished. Dr. James Arnott, who has given great attention to the local effects of graduated temperature in the treatment of various affections, has relieved neuralgic pains by the application of a mixture of salt and pounded ice, and has also rendered the surface of the body so insensible, that the introduction of setons, and other operations of a superficial nature, have been performed without pain. Dr. Arnott calls the process congelation; but the hardness which is produced in the part must depend on the solidification of the adipose substance; for if the water which enters into the composition of the tissues were frozen, then intimate structure would be destroyed, and a slough would be the result.

The effects of ether and chloroform on the appearance of the blood agree perfectly with the view above given of their modus operandi. There is generally no alteration in the complexion of the patient, or in the colour of the mixed venous and arterial blood as it flows from the wound, so long as the inhalation is not pushed to the extent of embarrassing the respiration, and provided the patient is not holding his breath, on account of the pungency of the vapour, or a general state of rigidity which sometimes occurs for a minute or two; but when the blood which flows from the arteries and veins can be separately observed, whilst the patient is well under the influence of the narcotic, it is seen that the arterial blood is somewhat less florid, and the venous blood less dark than under ordinary circumstances. The lighter colour of the venous blood, which has been spoken of by Dr. Gull, as well as by myself, points particularly to a diminution of oxidation in the systemic capillaries.

The phenomena attending the irritability which remains in the muscles for a longer or shorter time after death, and particularly the effect of narcotics on this irritability, accord exactly with the views above expressed. It can be shown, by the following amongst other reasons, that the muscular irritability depends on a little oxygen still remaining in the blood contained in the muscular tissue. Nysten* found that the injection of oxygen gas into the cavities of the heart increased the vigour and duration of the contractions. 

(*Recherches Physiologiques, p. 335). 

Sir B. Brodie states that, in dogs in which the circulation was kept up after death by artificial respiration, "there seemed to be actually an increased irritability of the voluntary muscles, continued not for a short time, but even for an hour and a half."†

(†Physiological Researches, 1851, p. 108.)

Nysten informs us‡ that the general result of his observations on the duration of the muscular irritability in animals of different classes, and of different orders of the same class, was in the inverse ratio of the muscular energy developed during life and we previously saw, on the authority of Edwards, that this was just the ratio of duration of life under privation of air or asphyxia.

(‡Opus cit. p. 355).

Chloroform ether, alcohol, and probably all narcotics, have the power of suspending the muscular irritability. In a former paper of this series§ some experiments were related in which the irritability of the heart in frogs and rabbits was removed by the vapour of chloroform; and in two of the experiments the irritability was alternately allowed to recover by letting the chloroform evaporate, and then suspended again by a fresh exposure to the vapour.

(§ Vol. xlii. p. 415 [part 5], 614 [part 6])

In one of these experiments the peristaltic action of the small intestine of a rabbit was arrested by the local action of chloroform. I have frequently stopped the quivering motion of the intercostal muscles, which is seen on opening the chest of an animal immediately after death, by blowing a little vapour of chloroform on them through a tube. On one of these occasions Dr. Sibson was present.

The following experiments show the action of chloroform, etc., on all the muscles of the body:--

Exp. 80.--A half-grown guinea-pig was made to inhale chloroform in a glass jar till it ceased to breathe. The chest was then opened, and a tube armed with a stop-cock was introduced into the aorta and tied. The heart was still contracting, and the muscles were very sensible to the shocks of an electromagnetic apparatus. Fifteen minims of chloroform, and two drachms of tepid water, which had been agitated together till the chloroform was suspended in minutes globules, were now injected. At the moment of injection the right anterior extremity and the two posterior extremities were stretched out, and the toes quivered. These limbs became quite rigid at the moment of the injection, as did also the neck and trunk of the animal. The left anterior extremity remained flexible. The wires of the battery were applied to the muscles of various parts of the body immediately after the injection, but no contractions could be excited, except in the left anterior extremity, and the muscles of the chest on the same side, which remained as irritable as before; the reason of this being that the injection had not entered the left subclavian artery. The heart ceased to act at the moment of the injection, and was afterwards quite insensible to the shocks of the battery.

Exp. 81.--A similar guinea-pig to the last was killed by the inhalation of ether, and was opened immediately after it ceased to breathe, whilst the heart was still acting. The tube was secured in the descending aorta, and two fluid drachms of sulphuric ether were injected. The posterior extremities were stretched [1056/1057] out at the time of the injection, and there was a quivering motion of the toes. These extremities, together with the posterior half of the trunk, became instantly affected with post-mortem rigidity, and were totally insensible to the shocks of the electro-magnetic battery. The anterior extremities, and, indeed, all the anterior part of the body which had not been injected with ether, remained sensible to the shocks of the battery, and only became rigid between two and three hours after death. The heart ceased to act at the moment of the injection, some ether having been dropped on it from the syringe.

Exp. 82.--An ounce of rectified spirit of wine was injected into the aorta of a cat immediately after death from chloroform. There were muscular contractions at the moment of injection, but no contractions could be excited afterwards by mechanical irritation, although the muscles were very irritable just before, and were quivering when not touched. The heart, which was previously beating, also ceased to act. Post-mortem rigidity began to take place five minutes after the injection, and it still existed eight days afterwards.

Exp. 83.--A cat was killed by inhalation of chloroform, and three minutes after death three drachms of rectified spirit of wine, of 80 per cent, were mixed with three drachms of water, and injected into the descending aorta. The posterior extremities were stretched out at the moment of the injection, and almost immediately began to be rigid; and in less than ten minutes after the injection, the whole of the posterior half of the body was very rigid, whilst the anterior parts were quite flexible. An hour after death rigidity was commencing in the anterior extremities, and in half an hour more they and the neck were quite rigid. This cat was killed on Dec. 1st, 1850, and was kept in a room with a fire. The rigidity of the anterior half of the body began to subside at the end of a week, but that of the posterior extremities not till a fortnight had elapsed; and they were still quite fresh, although putrefaction was commencing in the chest and neck.

As absorption of vapour continues in the frog by its skin after the respiratory movements have ceased, it is not necessary to resort either to dissection or injection in them, as in mammalia, in order to cause the extinction of irritability, and bring on the post-mortem rigidity. It can be induced in a very few minutes by exposure to the vapour of ether or chloroform, although, under ordinary circumstances, the muscles remain long irritable and flexible in these animals. In some interesting experiments lately detailed in the Medical Gazette by Mr. W. F. Barlow,* that gentleman produced rigidity in a single limb of living frogs without much affecting the rest of the animal; he also observed what I had previously remarked,† that the setting in of rigidity in these animals is sometimes accompanied by a movement of the body.

(*Page 713)

(†[part 5] Med. Gaz., vol xlii. p. 415).

The state which is called post-mortem rigidity appears to be the natural condition of muscle when no kind of change in its composition is taking place. As long as the feeble oxidation continues, which enables it to be irritable after death, it remains flaccid; but when this ceases, from want of oxygen from reduction of temperature, from the counter affinity of a narcotic, or from exhaustion of the nutrient materials, the muscle becomes rigid, and remains so till a new kind of oxidation--that of putrefaction--commences, when it again becomes flaccid. Although the muscles, when affected with this kind of rigidity, are in a state of completely suspended animation, they are not always incapable of again living; for M. Brown-Seqnard has restored the irritability of the muscles of a dead guinea pig after they had been rigid from ten to twenty minutes, by making the blood of a living animal of the same species circulate in its vessels. Although reducing the temperature hastens rigidity, it is not essential to it; for I have seen a fœtus at the full term born in a state of complete rigor mortis.

In a former paper,‡ several proofs were given that chloroform and ether do not prevent oxidation in the system by themselves combining with the oxygen of the blood . Among these proofs were some experiments showing that the chloroform and ether are exhaled again unchanged from the blood as it circulate through the lungs. The paper of next week will contain an inquiry into the manner in which these narcotics act in limiting and preventing oxidation in the living frame.

(‡[part 13] Vol. xlv. p. 626)

(To be continued)

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68. "On narcotism by the inhalation of vapours."

Source: Snow, John. London Med. Gazette 48, 26 December 1851, pp. 1090-94 (part 18).

[Part 18]

Antiseptic power of narcotics--Narcotic vapours and gases prevent ordinary combustion--They prevent the slow combustion of hydrogen by means of spongy plotinum--They prevent the oxidation of phosphorus--Nature of the power by which narcotics prevent oxidation in the living body and out of it--Recapitulation.

During the last two years, whilst the investigation which I have been making respecting chloroform and ether, and publishing from time to time in the Medical Gazette, have been directed more particularly to showing the modus operandi of these agents, M. Robin, of Paris, has been engaged in a like inquiry, and has arrived at similar conclusions, although his researches have been made in a different manner. His opinion was given at the Academy of Sciences to the following effect;--That the anæsthetic action of the vapour of ether or chloroform is the result of a state of asphyxia more or less complete; but that this kind of asphyxia is produced by these agents, when absorbed, protecting the blood in the capillary vessels against the action of the oxygen, in the same way that they protect a piece of flesh, or any other animal substance that is plunged into them, against the action of the same agent oxygen, and thus prevent putrefaction* (*See Comptes Rendus, t. xxx. p. 52). [1090/1091] M. Robin subsequently gave his views to the Academy in a more extended form. He stated that all substances which will preserve dead animal and vegetable matters against putrefaction are capable of acting as poisons to all organised beings, whether possessed of a nervous system or not; that the action is independent of their coagulating or not coagulating albumen; and that it consists in the power they have of protecting organised matters from slow combustion by moist oxygen. He stated that they diminish or completely interrupt the combustion according to the quantity; and that, in proportion to the dose, they are sedative medicines to animals, and asphyxiating poisons to all organised beings.*

(*Comptes Rendus, t. xxxi. p. 383; and Med. Gaz. vol. xlvi. p. 590).

The following are amongst the substances enumerated by M. Robin as having the properties in question:--Sulphuric ether, chloroform, benzin, Dutch liquid, hydriodic ether, acetic ether, naphtha, sulphuret of carbon, camphor, protochloride of carbon, carburet of nitrogen, hydrocyanic acid, and arsenic. The first seven of the above agents are amongst those whose narcotic effects I have described in the Medical Gazette.

The antiseptic power of these and other substances is probably in direct proportion to their narcotic strength; at all events, I have ascertained that such is the case as regards chloroform, ether, and alcohol. A few drops of chloroform, when put into a bottle, form enough vapour to prevent putrefaction in a piece of flesh suspended in it; but it requires a larger quantity of ether, which is a less powerful narcotic, to produce a like effect. One part of ether, when mixed with nine or ten parts of water, preserves animal matters; but a larger proportion of alcohol is required for a like effect; and alcohol, as is well known, requires to be taken in much larger quantity than ether to cause insensibility. I have often observed the antiseptic powers of chloroform, even in the small quantity which suffices to cause the death of an animal, especially when it has been inhaled slowly, so that the tissues were intimately impregnated with it. For instance, the cat which formed the subject of Experiment 73 in a former paper, and which was killed with chloroform, was kept for sixteen days in a temperature between 50° and 60° Fahr., and, at the end of that time, the rigor mortis was only beginning to subside, and putrefaction had scarcely commenced.*

(*I am persuaded that the antiseptic properties of various substances are capable of producing greater advantages than they have hitherto, especially if applied by the method of injecting the arteries immediately after death, which was described in my last paper. Owing to the difficulty of curing meat by the ordinary methods in tropical climates, thousands of oxen and sheep are slaughtered in South America and Australia, for the tallow and hides, whilst the flesh is left to rot; when, by injecting the vessels, it could be immediately rendered as firm as in the coldest climate. There would probably be a prejudice against using a medicine such as chloroform for this purpose; but it fortunately happens that the essential oils, which exist in nearly all condiments, are both narcotic and antiseptic. I have frequently made insects insensible by exposing them in a covered vessel to the vapour of oil of peppermint; and, on one occasion, I rendered a linnet insensible by the inhalation of the vapour of oil of lemons: by injecting twenty minims only of the latter essential oil (shaken up with an ounce of water) into the arteries of a rabbit after death, it kept very well for seventeen days. I have found that injecting with a saturated solution of common salt very much hastens rigidity, although it does not produce it immediately. I hope that some one who has the opportunity will follow up this subject, as it promises to yield a kind of wealth more useful than the newly discovered treasures of California and Australia.)

The substances which have the property of limiting and preventing oxidation in the living body, have also the property of limiting and preventing that kind of oxidation which constitutes ordinary combustion. If, for instance, as much ether as will make not less than about eight cubic inches of vapour be diffused through the air of a bottle or jar holding one hundred cubic inches, and a lighted taper be lowered into the vessel, it will be extinguished. The vapour of ether will take fire at the mouth of the bottle; but the taper will go out as it descends into the air mixed with vapour not in a state of combustion. Flame is extinguished also by the vapour of chloroform when in sufficient quantity, and by many other vapours and gases. Sir Humphry Davy, whose investigations on flame resulted in the discovery of the safety lamp, thought at first that the power of preventing combustion in these instances depended on the cooling power of the gas employed as a diluent; but, on making experiments with various gases he found that some other cause or causes existed. Olefiant gas had a much greater effect in preventing the explosion of oxygen and hydrogen by the electric spark than any of the other gases employed by Sir H. Davy, and this gas is a more powerful narcotic than carbonic acid, or any of the others he used, except sulphuretted hydrogen (which probably acts in a different manner from ordinary narcotics), for I have found that olefiant gas causes immediate insensibility in birds, when mixed with the air in the proportion of one part to ten.

Dr. Henry, and Professor Graham,* have ascertained that a number of gases have the effect of preventing the slow combination which takes place between oxygen and hydrogen with the aid of spongy platinum, and that the relative power of the various gases is nearly the same in this instance as when the electric spark is employed, olefiant gas being the most powerful.

(*Quarterly Jour. of Sc., 1829, part ii, p. 354.)

Professor Graham discovered† that a number of vapours, as well as gases, have the property, when mixed with atmospheric air, of preventing the slow oxidation of phosphorus, which renders it luminous in the dark. He found that olefiant gas, and the vapour of oil of turpentine, and of other essential oils, possess this power, even when present in a very minute quantity. I expressed an opinion nearly five years ago,‡ that the action of ether on the human frame was of the same kind as that by which it prevented the oxidation of phosphorus ; and this view is supported by the fact, that amongst substances of a similar constitution, whose narcotic power is known, this power bears a direct relation to the power of preventing the oxidation of phosphorus. For example, I find that the vapour of alcohol has but little influence in this respect, whilst Prof. Graham found that the vapour of ether, in the proportion of one part to 150 of air, prevents the oxidation of phosphorus at all temperatures up to 64° Fahr.; that one part of olefiant gas (which is a more powerful narcotic) has a like effect in 450 parts of air; and that one part of vapour of naphtha exerts this influence when diluted with 1820 parts of air. Now naptha consists chiefly of benzin, which, as was stated in a former paper, causes insensibility when less than a grain of it i[s] diffused in each hundred cubic inches of the respired air. Professor Graham ascertained that hydrochloric acid gas promotes the oxidation of phosphorus in the air; and I find that the vapour of chloroform does not prevent it: this is probably due to the chlorine it contains in such large quantity.

(†Op. Cit.)

(‡See Med. Gaz., vol. xxxix. p. 333)

Professor Graham states that olefiant gas prevents phosphorus and hydrogen from uniting with oxygen without undergoing any change itself. This is exactly analogous to the action of ether and chloroform in the human body, which, as shown before, produce their effects, and pass off unchanged in the expired air.

Having traced the narcotic action of ether and other bodies to the more general law of their power of preventing oxidation under a great variety of circumstances, the mind naturally inquires by what kind of power oxidation is thus prevented. I feel considerable diffidence in offering a theory on a subject which falls as much within the domain of ordinary chemistry, as within that of physiology, when so eminent a chemist as Professor Graham has investigated a number of its details without suggesting any general explanation on the matter. However, as I have formed a theory in my own mind, I offer it for consideration: it is to the following effect:--That chemical attraction or affinity is a constantly acting force, by which each atom of matter exerts an influence on all other atoms within the sphere of its attraction, whether they are of the same or of a different kind, the force of the attraction varying with the respective nature of the substances, and the physical conditions in which they are placed. In this point of view, it will be seen that any two substances in a condition to unite together might be prevented from doing so by the intervention of a third body possessing a sufficient attraction for either of the others; and it would not be necessary that this third body should itself enter into chemical combination; for a balance of forces might be established, so that the three substances would remain exerting reciprocal attractions for each other, but unable to enter into more intimate union.

In the instances of prevented oxidation previously considered, the interfering substances no doubt owe their influence to their attraction for oxygen. These substances, in fact, are known to possess a strong affinity for oxygen, being nearly all of them highly combustible. Those of them which have the greatest power in preventing oxidation--olefiant gas and benzin--contain no oxygen in their composition; whilst the oxide of ethyle, which contains rather more than one-fifth of its weight of oxygen, has less power; and alcohol, which consists of oxygen to the extent of rather more than one-third, has much less power than ether as a narcotic, as an antiseptic, and in preventing the oxidation of phosphorus. The salts of ethyle, without oxygen, produce narcotic effects also in much smaller doses than its oxygen salts. It was previously shown that the narcotic powers of the ethers and other allied agents was in the inverse ratio of their solubility in water,--a generalization which is in perfect accordance with what is now stated; for it so happens that the agents of this class which contain oxygen are more soluble than those which do not.

As regards their application to the substances when acting as narcotics, the views just explained may be thus briefly stated. When absorbed into the blood, they have attraction for the oxygen dissolved in it; and though unable to combine with the oxygen under the circumstances, the attraction is sufficient to counteract that existing between the oxygen, on the one hand, and the certain constituents of the blood and tissues of the organs, on the other; and thus the combination between the respired oxygen and the materials of the body--those changes which are, in a manner, the essence of all the animal functions--are prevented more or less completely, according to the dose of the narcotic.

There is a curious circumstance connected with the oxidation of phosphorus, to which it is necessary to allude. Professor Graham found that pure oxygen has no action on phosphorus under the atmospheric pressure, at temperatures below 64°; but that a slight expansion of the gas, by diminishing the pressure two or three inches, or diluting the oxygen with nitrogen, hydrogen, or certain other gases, enables it to act on the phosphorus, which then becomes luminous in the dark. The explanation I would offer of this circumstance is, that the attraction or affinity of the atoms of oxygen for each other is sufficient to prevent their combining with the phosphorus until that attraction is weakened by their separation to a greater distance by the diminution of the pressure of the intervention of the atoms of another gas.

In dismissing this part of the subject I should like to remark, that whatever may be thought of the above explanation of the power by which certain narcotics retard or arrest oxidation in the animal frame, will not affect the fact of these narcotics acting in this way, for it rests on distinct evidence previously stated.

I have said nothing of the stimulant or irritant properties which chloroform, ether, alcohol, and probably all narcotics, possess in a greater or less degree, and I have not space to enter on that subject; but I expect to be able to show on another occasion, that the irritation caused by narcotics is not opposed to the view of their acting in the way explained in the previous pages.

These papers on narcotism by the inhalation of vapours have extended over a very much longer time than I expected, and I have done after all much less than I intended. In now brining them to a close, however, it may be well to give a brief recapitulation of the more prominent points which I have endeavoured to establish.

Several experiments with chloroform and ether were described, the object of which was to determine the quantity of these agents which exists in the blood in a state of insensibility. The method employed was that of placing a small animal in a large vessel, containing a known quantity of vapour mixed with the air, and allowing it to remain till the effects of the vapour no longer increased, but became stationary; when, the solubility of the vapour in the serum of the blood being known, the quantity absorbed could be calculated from the relative saturation of the air. It was found that, with both chloroform and ether, the proportion, in a state of complete insensibility, was about one twenty-eighth part as much as the blood would dissolve. Similar experiments were made with several other substances, including some salts of ethyle, benzin, bromoform, Dutch liquid, and sulphuret of carbon, and it was found that the proportion absorbed into the blood, in causing insensibility, was nearly the same as in the case of ether or chloroform. Hence the rule was deduced, that the narcotic strength of these substances was in the inverse ratio of their solubility. The agents to which this rule applies resemble chloroform and ether in containing carbon, and not containing any nitrogen as a radical element, and some of them were used as was described with success, in preventing the pain of surgical operations.

A description of the influence of chloroform was given, in which the effects it produces, if continued until respiration is suspended, were divided into five degrees. It was stated that when chloroform is given to animals neither very quickly or slowly, and continued till the breathing is arrested, the heart continues to beat; but some experiments were detailed which show that chloroform is capable of arresting the action of the heart, if absorbed in sufficient quantity.

The cases of accident from inhalation of chloroform, which had happened up to the time of writing, were next considered, when it appeared that the fatal event in these cases was due to the vapour of chloroform being given in too concentrated a form, by which not only was the breathing suddenly arrested, but the action of the heart was also paralysed by the effect of the vapour.* (*The fatal cases which have since happened, together with some that narrowly escaped being fatal, entirely confirm the opinion then expressed. The alarming symptoms always came on in the most sudden manner, the action of the heart being suspended without previous warning, although in some of the cases there had been at first an apparent difficulty in rendering the patient insensible. No means were used in any of these cases to insure a proper dilution of the vapour with air, a handkerchief being merely employed for administering chloroform, except I believe in one case, where it was not administered by a medical man.)

The opinion was expressed that chloroform, if given gradually and with due care, may be safely employed in every case in which a surgical operation has to be performed; an opinion in which I have been altogether confirmed by further experience.

Directions were next given for the administration of chloroform in various kinds of operations; the conditions and diatheses which influence its action were considered, and a numerical result of the larger operations in which I had administered chloroform or ether at that time was given, by which it was shown that the result had been favourable.

After some remarks on the use of Dutch liquid in operations and midwifery, some experiments with alcohol were detailed, by which it was shown to resemble ether and chloroform in its effects and mode of action. Experiments were related showing that chloroform passes off unchanged in the expired air; that it can be detected in limbs amputated whilst patients are inhaling, and also in the dead bodies of animals killed by it. It was next shown that ether and alcohol can be detected in the expired air, and that the quantity of carbonic acid excreted by the lungs is diminished under the influence of chloroform and ether. For these and other reasons the conclusion was arrived at, that the class of narcotics we have been considering, and probably other narcotics also, produce their effects by virtue of a power they possess of retarding the action of the respired oxygen on the blood and tissues of the body.

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