book background

"WMS: Snow and Golding Bird on carbonic acid poisoning"

(1 December 1838)

First topic was discussion of delirium tremens. Thereafter, "Mr. Snow inquired of Dr. Golding Bird whether, in the statement be had made to the Society on a previous evening, viz., that from eight to ten per cent. of carbonic acid in the atmosphere would be fatal to life, he meant simply an adulteration of the atmosphere by the admixture of that quantity of carbonic acid, or the deterioration of the atmosphere by decomposition, so as to produce that proportion of carbonic acid in it, as in a brewer's vat, or in a chamber where the burning of a charcoal stove had occurred.

Dr. Bird replied that his opinion was derived from certain experiments performed by Müller, as well as experiments conducted by himself. He thought that an atmosphere impregnated with that quantity of carbonic acid would be fatal to life.

Mr. Snow now made some observations in a very low tone, and consequently his meaning could not be very well caught. He stated that an important difference existed between the two cases, although the fact had not been noticed by any writers. Death did not arise in either case from the sedative power of the carbonic acid gas, but from the deficient quantities of oxygen in the atmosphere. [He eventually altered this opinion after listening to Dr. Bird's paper on the subject in March 1839.] The lungs could only extract a certain volume of oxygen from the air, in consequence of the affinity which one gas bore to another. When an atmosphere is deteriorated by respiration, by a charcoal stove, or by any other chemical process, the proportion of the constituent gases is very different from what it would be in the case of a simple adulteration of the atmosphere by the addition of 10 per cent. of the deleterious gas, for the process of combustion not only adds carbonic acid to the atmosphere, but abstracts a large portion of its oxygen, and thus in three ways renders it unit for respiration: 1, by adding a quantity of carbonic acid; 2, by abstracting from the wholsome [sic] proportion of oxygen; and 3, by setting free another deleterious gas, the nitrogen. .017 of carbonic acid gas generated by the burning of charcoal, would be equally destructive with .08 of the same gas introduced by simple mixture. Mr. Snow had mixed certain gases, and had respired with impunity as much as .40 of carbonic acid, when the proportion of oxygen was increased in an equal degree, and he inferred, from his experiments, that the absence of oxygen, not the presence of carbonic acid, or any other gas, was the usual cause of death in cases of asphyxia from deteriorated atmosphere.

Dr. Bird thought the physiological effects of the carbonic acid would be the same, when the proportion of the gas in a given atmosphere was similar, whether the gas was added to the atmosphere, or the atmosphere was deprived of part of its oxygen by the combustion of charcoal. The observation of Mr. Snow, touching the emancipation of the nitrogen, he thought interesting, and had a practical application; for if in a chamber containing 110,000 cubic feet of respiratory atmosphere, 49 pounds of charcoal were burnt in ten or twelve hours, not only would 1500 cubic feet of oxygen be absorbed, but 9,000 cubic feet of irrespirable nitrogen would be set free, and thus two poisonous gases would at one time exert their influence upon the living frame of the inmates.

Dr. A. T. Thomson considered that it would be interesting to measure the sedative and suffocative influence of the carbonic acid gas. In some cases death was produced gradually by apoplexy from the absorption of this gas, by the lungs of a person lying near a stove. When an animal was suddenly placed in an atmosphere containing this gas, the glottis closed, and death from suffocation occurred. Dr. Priestley had proved the sedative property of carbonic acid, for having burnt his hand, its immersion in a jar of carbonic acid immediately relieved him.

Professor Everitt thought it important to ascertain how much less than .10 of carbonic acid in the atmosphere could for a length of time be inhaled with impunity. It was admitted by the several proprietors of the various stoves, that by the combustion carried on in them, one per cent. of the deleterious gas was added to the atmosphere. How long could such an adulterated atmosphere be respired without danger or injury. For his part, he should not like to breathe in such a medium, especially when he recollected the result of the experiments of Saussure, who was the greatest chemical authority on the subject. That eminent philosopher had made many thousand experiments on atmospheric air, taken from high and low situations, at all seasons of the year, at all times of the day and night; in crowded assemblies and in the open plain, and in short under every variety of circumstances, and the maximum of carbonic acid obtained in any case was .0004. The one per cent. of carbonic acid introduced in the atmosphere of air by the combustion carried on in these stoves was twenty-five times in amount what the natural state of the air contained. It was for medical gentlemen to decide what the effect upon health of the habitual use of such an apparatus would be. Some people, he had observed, were peculiarly sensible of the presence of the gas; and a very slight increase of what might be called its normal proportion, caused disagreeable symptoms.

Dr. Bird would bear his testimony as to the different susceptibility of individuals to the influence of carbonic acid gas. He had notes of three instances which proved the truth of Mr. Everitt's observations. 1. Two sisters, in Paris, slept together in a room where was charcoal burning in a chafing dish. One sister slept with impunity, but in the morning she found her sister dead by her side. 2. In a second instance, related to him by Mr. John Read, the mechanician, a young woman, with her husband and her child (very young), slept in a room where burning charcoal was put in the fire-place. The husband, on rising in the morning, found his wife dead and his child insensible. 3. The third instance was that of two medical students in a dispensary, who, in cold weather, burnt charcoal in a warming-pan, to keep them warm. In a short time one of them fell down senseless; the other remained unaffected.

Mr. Everitt supposed that every body was familiar with the inconvenience experienced from the use of the stoves in Germany. In that country the fire was not in the room, and consequently the inconvenience was not the effect of any deterioration of air. It arose from the great dryness produced by the want of circulation of air, and the consequently greatly increased evaporation from the surface of the body. In his opinion, it was a chemical law that all gases had a strong tendency to intermingle, and would do so in a given time. Carbonic acid evolved from a brewer's vat, or from a stove, would soon diffuse itself in the atmosphere of a room. The gas given off from a stove being of a higher temperature than the surrounding air, would ascend; but the motion of the air would soon cause it to mix equally. There would he no more danger near the stove than away from it.

Dr. Bird agreed with Mr. Everitt that the admixture of gases in a small apartment would quickly take place, and the specifically lighter gas would ascend, as in the case of the heated carbonic acid; but it would only ascend until it had disengaged itself of its caloric, when it would rapidly descend. But in the immediate neighbourhood of the stove the stratum of air would be heated, and its specific gravity so much diminished that the newly generated carbonic acid would at once intermix with it. In fact, in the large stove in St. Michael's church, Cornhill, a stream of carbonic acid could be ascertained to be descending from a hole in the side in a parabola to the ground. He thought the objection obtained equally against Dr. Arnott's stove as against any other.

To prevent the dryness of the atmosphere produced by these stoves, he recommended a wet sponge to be placed in a flat dish, with a perforated cover. From this a constant evaporation would be kept up.


"Westminster Medical Society." LMG 23 (1838-39): 425-27.

* * *

[Meeting of 1 December 1838 - same as above, but a different reporter and a more fulsome account of Snow's intercession:

"Mr. Snow asked Dr. G. Bird if, in the statement he had made to the Society at the last meeting, that from eight to ten per cent. of carbonic add gas in the atmosphere would be fatal to life, he meant that quantity of gas mixed with the atmosphere in experiment, or arising from a brewer's vat, or [418/419] when produced by respiration, or by the burning of a stove?

Dr. Bird replied, that as few persons had had experience with respect to cases of poisoning by carbonic acid, we were guided in the expression of our opinions by the experiments of others, or those performed by ourselves, and these experiments had led to the conclusion that an atmosphere impregnated with from eight to ten per cent. of carbonic acid, would be destructive to life. He did not wish, at the present moment, to enter on the subject, as he was pursuing a series of experiments which he trusted would throw some light on it.

Mr. Snow had asked the question because neither Christison, Orfila, nor any of the numerous authors to whom he had referred, made a distinction between the two cases. He was prepared to show there was a very wide difference. Death, he believed, in neither case arose from any sedative effect of carbonic acid gas, but from the diminished quantity of oxygen in a given volume of air; the lungs, as was known, were capable of extracting only a certain portion of the oxygen from another gas, owing to the affinity which one gas bore to another. [He altered his opinion after listening to Dr. Bird's paper on the subject in March 1839; see below.] Now, when charcoal was burnt, or the gas was given out by respiration, the gas was formed at the expense of the oxygen of the air, and hence it must follow that an atmosphere containing a given quantity of carbonic acid gas arising from these causes, would be equally deleterious with one in which there were five times the quantity introduced by simple mixture. Tables were now shown to prove that about one and two-thirds per cent. of carbonic acid gas, produced by the burning of charcoal, formed an atmosphere in which the oxygen was as much diminished as though eight per cent. of the carbonic acid gas had been introduced into it by simple mixture; it would hence follow that, for the production of an atmosphere equal, as regarded oxygen, to one in which eight or ten per cent. of carbonic acid gas was formed from the burning of a stove, the large quantities of more than thirty-seven and forty-eight per cent. must be added by simple mixture. The reasons why carbonic acid gas was supposed to have a sedative effect were chiefly these :-First. Collard De Martiny had found that, when he substituted carbonic acid gas for the nitrogen of the atmosphere, animals perished in the short space of two minutes in a mixture containing one volume of oxygen and four volumes of carbonic acid. Death in this case would, however, arise from the mere pungent effect of the large quantity of the carbonic acid on the glottis, producing its closure, and, consequently, asphyxia. Secondly. That when a solution of the gas was taken into the stomach, as in soda-water, its absorption sometimes produced sedative effects; there was no proof, however, that the gas could be absorbed by the lungs, and the fact that we were giving it out from them every minute of our lives, offered a strong presumption to the contrary. Thirdly. That a person having his body inclosed in carbonic acid, and breathing the natural atmosphere, suffered from disagreeable sedative effects. Now, the gas might be absorbed by the skin, and not by the lungs. Dr. Edwards, of Paris, had, indeed, fully proved that a certain extent of respiration was performed by the skin, and the mere suspension of this function would produce the effects alluded to. Judging from his (Mr. S's) own feelings, when respiring an artificial atmosphere, it made no difference whether a portion of carbonic acid was present or not, provided the quantity of oxygen was the same. He had also found that the presence or absence of carbonic acid exerted little or no influence over the combustion of a common candle, when the oxygen remained the same. On comparing his own experiments on combustion, with those of Dr. Edwards on animals, he had found that animals would live in an atmosphere containing much less oxygen than was required to support a burning candle; yet Dr. Christison relates the case of a girl who fell insensible in a beer cellar, while a candle continued to burn. This fact illustrated the difference which constitution exercises over the effects of poisons. Dr. Reid, at the late meeting of the British Association, had stated that ten per cent. of carbonic acid gas caused uneasy feelings in the dark, though it could be well supported in a strong light. Two per cent., as he (Mr. S.) had shown, produced from a burning stove, would equal the ten per cent. by mixture. Dr. Christison had shown that persons would die of apoplexy in an atmosphere which produced no disagreeable feelings at first; an atmosphere, then, in which charcoal has been burning, containing but a very small quantity of the gas, would be sufficient to cause death; he (Mr. Snow) had that evening inhaled a mixture of ten, twenty, and forty per cent. of the gas with common air, and it had not even produced irritation of the fauces. He considered the statement in Dr. Thomson's "Materia Medica" would be found correct, that when carbonic acid was pure it produced closure of the glottis, and that this effect could be produced when the gas was mixed with an equal bulk of common air.

Dr. Golding Bird considered the physiological effects of carbonic acid gas would be the same when the quantity was similar, whether the gas was added to the atmosphere, or the atmosphere was reduced of its oxygen by the combustion of charcoal. One important deduction was to be obtained from the observations of Mr. Snow: if, for instance, in a small chamber, containing 110,000 cubic feet of atmosphere, 49 pounds [419/420] of charcoal were to be burnt in 11 or 12 hours, 1500 cubic feet of oxygen would be absorbed, and not only this, but 9000 cubic feet of irrespirable nitrogen would be set free.

Dr. A. T. Thomson said, it would be interesting to determine the difference between the sedative and suffocative influence of carbonic acid gas. In cases of suicide by this agent, from the party lying near a stove in which charcoal was burning, the gas was taken into the lungs, and death produced gradually from apoplexy. When the person was suddenly immersed in an atmosphere containing the gas the air-passages closed, and the person died of suffocation. Dr. Priestly had proved the sedative power of carbonic acid, for, having burnt his hand, he placed it in a jar of this gas, and the pain was instantly relieved.

Mr. Snow said, the relief obtained in this case arose, probably, from the removal of the hand from the irritating influence of the oxygen of the air, and not from any sedative effect of the gas itself.

Mr. Everitt thought it would be most interesting to ascertain, by experiment, how much less than ten per cent. of carbonic acid gas in the atmosphere could be breathed for a long time without danger. Saussure had made many thousands of experiments on the atmosphere, taken from high and low situations, and at all seasons, and the mean maximum of carbonic acid contained in it was 4 in 10,000. Now, it would be a point of much importance to determine how far this quantity could be increased with impunity; it was difficult to arrive at this conclusion. It was said, on the late inquest, that the atmosphere in the church contained one per cent. of carbonic acid only; yet what an increase was this on the maximum contained in the natural atmosphere! Some people were particularly sensitive with regard to this gas. He had found, when lecturing at public institutions, that the gas evolved from a very small charcoal chafer so affected two or three ladies that they were obliged to leave the room; others had observed this fact as well as himself, and gentlemen who sat near him during his lecture had requested him not to burn charcoal, as it produced headach [sic]and other unpleasant symptoms. He was inclined to believe that carbonic acid, obtained from the burning of charcoal, was more deleterious than that produced from chalk, or by fermentation. Now, there was a wide range between ten per cent. and the maximum quantity found in the atmosphere. How far beyond this latter could we safely go? With regard to himself, he should be unwilling to increase much the quantity which Nature had given; he should be unwilling to breathe an atmosphere containing one per cent. of the gas. In considering this question he thought we ought to sail far on the safe side.

Dr. G. Bird agreed with Mr. Evetitt that some individuals were much more readily affected by the gas than, others. Notes of three cases illustrating this he had in his possession. The first of these occurred in Paris: two sisters slept together in a room in which there was charcoal burning in a chafing-dish; one sister was alive the following morning, the other dead. In the second case, a young woman, previously in good health, with a child, aged two months, and her husband, slept in a room in which there was a good-sized chimney; a chafing-dish, containing burning charcoal, was placed near the chimney; the husband, on awaking in the morning, found his wife dead, and the child in a state of asphyxia. The third case was that of an assistant apothecary, who filled a warming-pan with charcoal in a small room in which he was at work; in a few minutes he became asphyxiated; a person in the room, perhaps a little farther off from the warming-pan, suffered nothing.

In answer to a question,

Mr. Everitt said, it was a chemical law that all gases diffused themselves uniformly if time were allowed for this to take place; carbonic acid, for instance, evolving from a brewer's vat, would, at first, fall to the ground, but would soon become mixed with the atmosphere of the room; the carbonic acid gas given off from a burning stove, being of a higher temperature than the surrounding air, would ascend, but the agitation of the air in the room would soon mix it equally around; there would be no more danger close to the stove than away from it, with the exception that the heat might he injurious. In all stoves in which there was not a free ventilation the air of the apartment acquired a greater capacity for moisture, and, unless some artificial means were resorted to, to correct this, breathing would become oppressed.

Mr. Chance referred to some valuable experiments on burning charcoal, by Mr. Coathupe, which were inserted in a late Number of The Lancet?* (*No. 8, p. 262.)

Dr. Bird said that the objection against stoves not having a free ventilation held good with respect even to Dr. Arnott's invention; to prevent the excessive dryness of the air arising from its use, he (Dr. B.) had adopted a very simple plan, with complete effect; he had a small flat dish, with a perforated cover, placed on the top of the stove; in this dish he placed a piece of moistened sponge, the evaporation going on from which rendered the air moist and pleasant. He agreed with Mr. Everitt with respect to the admixture of gases in a small room quickly taking place, and that, at first, the specifically lighter one, as in the case of the heated carbonic acid, would [420/421] ascend; in a larger building, such as St. Michael's Church, however, an the heated gas had a great number of feet to rise, he had found, as far as experiments had gone, that the gas ascended only a few feet, and then, giving out its caloric, fell downwards. From one opening in the large stove in the above church the carbonic acid might be caught in a vessel as it was descending; of course, however, time, even in this building, would produce an equable mixture of the gases.

"Westminster Medical Society." Lancet 1 (1838-39): 418-21.

bottom of book image