Disputes have also arisen as to the precise nature of the emanations from burning charcoal,—some believing that carbonic acid is alone discharged in such quantity as to prove injurious, and is singly sufficient to account for the effects which have been observed,—while others maintain that carbonic oxide, carburetted-hydrogen, or some peculiar pyrogenous vapour, may be also formed, and prove the real cause of the active properties of the vapour. According to the researches of Orfila, charcoal in a state of vivid ignition emits carbonic acid only, a hundred parts of the consumed air having been ascertained by him to be composed of 42 azote, 46 common air, and 12 carbonic acid. But when the combustion is low, a hundred parts consist of 52 azote, 20 common air, 14 carbonic acid, and 14 carburetted-hydrogen; so that not only is the air more thoroughly consumed; but likewise an additional poisonous gas is brought into action.[[2076]] The difference thus indicated has been supposed to account for what is often observed in countries where charcoal choffers are much in use for warming close apartments,—namely, that the practice is attended with most danger when the combustion is low, and that it is unsafe to close the doors of an apartment till the fuel is in a state of vivid ignition. M. Guérard again maintains, that when the supply of air is incomplete and combustion low, carbonic oxide gas is formed in considerable quantity; and that this gas, confessedly a much more powerful narcotic than carbonic acid, is probably the cause of many cases of poisoning with charcoal fumes.[[2077]] M. Devergie doubts the exactness of Orfila’s experiments on this head, but gives no new analysis. He observes that charcoal-vapour gives the air of a room a peculiar odour and bluish misty appearance, the latter of which slowly diminishes, and in twelve hours disappears; and that possibly there may be both a little carbonic oxide and carburetted-hydrogen in the air. But nevertheless he is of opinion that the carbonic acid alone is adequate to occasion all the effects observed in man or animals.[[2078]] Professor Hünefeld is of a different opinion, and has supplied the most satisfactory explanation of the important fact, that charcoal fumes are most noxious when the fuel has been just kindled and burns low; for he ascertained that at first it gives out a pyrogenous acid, which occasions headache and tendency to sickness, and which is not a product of combustion at the moment, but exists ready formed; and that when charcoal is at a full red heat, this noxious substance is no longer given off.[[2079]] Mr. Coathupe also thinks the cause of poisoning by charcoal fumes is an unknown pyrogenous body, and not carbonic acid gas.[[2080]]—This department of inquiry is obviously susceptible of more precise information. But meanwhile, whatever may be the probability that, besides carbonic acid, some other gases, or some peculiar pyrogenous body, may occasionally exist in charcoal fumes, and increase their poisonous property, little doubt can exist that the carbonic acid is singly sufficient to account for all the leading phenomena.
M. Devergie has been led to the opinion that air, in which a fourth part of its oxygen has been converted into carbonic acid, and which therefore contains five per cent. of that gas, is amply enough impregnated to occasion death.[[2081]] This corresponds with the observations of M. Ollivier, who found that three per cent. was as much as could be breathed with impunity even for a moderate length of time.[[2082]] Less, however, will suffice to prove injurious or even fatal, if the air be breathed long. Mr. Coathupe inferred from a rough estimate, that in the dangerous experiment he made upon himself, the carbonic acid, if uniformly diffused in the apartment, which was probably the case, amounted to only two per cent.; but his data were inadequate.[[2083]]
Proceeding from the fact that five per cent. of carbonic acid is sufficient to cause death, Devergie points out what quantity of charcoal is required to form that proportion,—a question of no small moment in respect to charges of murder, concealed under the semblance of suicide by suffocation with charcoal fumes. And he shows, that a French bushel, or decalitre, weighing 3000 grammes, is sufficient for a close apartment of 1275 cubic mètres, that is 6·6 pounds avoirdupois for a space of 1666 English cubic yards, provided the gas be uniformly diffused.[[2084]] The quantity of charcoal burnt in a given case may be arrived at pretty nearly from the weight of ashes left, which is estimated in round numbers at a twenty-fifth by himself,[[2085]] and at a twentieth by Ollivier.[[2086]]
It is important to remark that complete closure of an apartment is by no means essential for the action of carbonic acid, whether disengaged within it or introduced from without. For poisoning has occurred, even where a window was partially open.[[2087]]
3. It is probable that in some circumstances a very small quantity of the mixed gases proceeding from the slow combustion of tallow and other oily substances will produce dangerous symptoms. Dr. Blackadder remarked in the course of his experiments on flame, that the vapour into which oil is resolved, previous to its forming flame round the wick, excites in minute quantities intense headache.[[2088]] The emanations from the burning snuff of a candle, which are probably of the same nature, seem to be very poisonous. An instance indeed has been recorded in which they proved fatal. A party of iron-smiths, who were carousing on a festival day at Leipzig, amused themselves with plaguing a boy, who was asleep in a corner of the room, by holding under his nose the smoke of a candle just extinguished. At first he was roused a little each time. But when the amusement had been continued for half an hour he began to breathe laboriously, was then attacked with incessant epileptic convulsions, and died on the third day.[[2089]]—The effects of such emanations are probably owing to empyreumatic volatile oil, which will be presently seen to be an active poison.
4. The vapours from burning coal are the most noxious of all kinds of emanations from fuel, and cause peculiar symptoms. But they are less apt to lead to accidents than the vapour of charcoal, as they are much more irritating to the lungs. This effect depends on the sulphurous acid gas which is mingled with the carbonic acid.
Sulphurous acid gas is exceedingly deleterious to vegetable life, being hardly inferior in that respect to hydrochloric acid. Dr. Turner and I found that a fifth of a cubic inch diluted with ten thousand times its volume of air destroyed all the leaves of various plants in forty-eight hours.[[2090]] I am not acquainted with any experiments on animals or observations on man regarding the effects of the pure gas. But it will without a doubt prove a powerful irritant.
Some of the peculiarities in the cases now to be mentioned were possibly owing to the admixture of sulphuric acid gas with the carbonic, both being inhaled in a diluted state. The cases are described by Mr. Braid, at the time surgeon at Leadhills. In March, 1817, several of the miners there were violently affected, and some killed, in consequence, it was supposed, of the smoke of one of the steam-engines having escaped into the way-gates, and contaminated the air in the workings. Four men who attempted to force their way through this air into the workings below were unable to advance beyond, and seem to have died immediately. The rest attempted to descend two hours after, but were suddenly stopped by the contaminated air. As soon as they reached it, although their lights burnt tolerably well, they felt difficulty in breathing, and were then seized with violent pain and beating in the head, giddiness and ringing in the ears, followed by vomiting, palpitation and anxiety, weakness of the limbs and pains above the knees, and finally with loss of recollection. Some of them made their escape, but others remained till the air was so far purified that their companions could descend to their aid. When Mr. Braid first saw them, some were running about frantic and furious, striking all who came in their way,—some ran off terrified whenever any one approached them,—some were singing,—some praying,—others lying listless and insensible. Many of them retched and vomited. In some the pulse was quick, in others slow, in many irregular, and in all feeble. All who could describe their complaints had violent headache, some of them tenesmus, and a few diarrhœa. In a few days all recovered except the first four and three others who had descended to the deeper parts of the mine.[[2091]]—Another accident of the same nature, and followed by the same phenomena, happened more lately at Leadhills.[[2092]] Similar accidents have been also witnessed by Mr. Bald, civil engineer, among the coal-miners who work in the neighbourhood of a burning mine belonging to the Devon Company. It is worthy of remark, that the men sometimes worked for a considerable length of time before they were taken ill. Such being the case, it will be readily conceived that the burning of the lights was not a test of the wholesomeness of the air. Here, as at Leadhills and in other instances already mentioned, the lights continued to burn where the men were poisoned.[[2093]]
5. Somewhat analogous to the symptoms now described are the effects of the gradual contamination of air in a confined apartment. Every one must have read of the horrible death of the Englishmen who were locked up all night in a close dungeon in Fort William at Calcutta. One hundred and forty-six individuals were imprisoned in a room twenty feet square, with only one small window; and before next morning all but 23 died under the most dreadful of tortures,—that of slowly increasing suffocation. They seem to have been affected nearly in the same way as the workmen at Leadhills.[[2094]] A similar accident happened in London in 1742. The keeper of the round-house of St. Martin’s, crammed 28 people into an apartment six feet square and not quite six feet high; and four were suffocated.[[2095]]
The morbid appearances left on the body after poisoning with carbonic acid gas have been chiefly observed in persons killed by charcoal vapour. According to Portal the vessels of the brain are congested, and the ventricles contain serum; the lungs are distended, as if emphysematous; the heart and great veins are gorged with black fluid blood; the eyes are generally glistening and prominent, the face red, and the tongue protruded and black.[[2096]]—Gorging of the cerebral vessels seems to be very common. Yet sometimes it is inconsiderable, as in two cases related by Dr. Bright, where, except in the sinuses and in the greater veins of the ventricles and substance of the brain, no particular gorging or vascularity seems to have been met with,—the external membranes in particular having been very little injected.[[2097]] This, however, is certainly a rare occurrence. Serous effusion in the ventricles and under the arachnoid membrane is very general, yet not invariable.—Dr. Schenck, medical inspector of Siegen, in reporting two cases of death caused by the vapours of burning wood, notices paleness of the countenance as a singular accompaniment of cerebral congestion; and calls the attention of medical jurists to the extreme calmness of the features as a general character of this variety of poisoning.[[2098]] Although the same appearance has also been noticed by others,[[2099]] the countenance nevertheless is often livid. But whether livid or pale, it is always composed.—It appears from an account in Pyl’s Essays of several cases of suffocation from the fumes of burning wood, that besides the appearances mentioned by Portal, there is usually great livor of the back, frothiness as well as fluidity of the blood, and more or less gorging of the lungs with blood.[[2100]]—A common appearance where the poisonous emanation has been charcoal vapour, is a lining of dark, or sometimes actually black dust on the mucous membranes of the air passages, thickest near the external opening of the nostrils, and disappearing towards the glottis. There are obvious reasons why this appearance cannot always be expected to occur; but when present, it may be in doubtful circumstances a very important article of evidence.[[2101]] In Wildberg’s collection of cases there is a report on two people who were suffocated in bed, in consequence of the servant having neglected to open the flue-trap when she kindled the stove in the bed-chamber; and in each of them Wildberg found all the appearances now quoted from Portal and Pyl. The tongue was black and swelled.[[2102]]—Mertzdorff has related a case of death from the same cause, in which, together with the preceding appearances, an effusion of blood was found between the arachnoid and pia mater over the whole surface of both hemispheres.[[2103]] In one of Dr. Bright’s cases there was a small ecchymosis in the cortical substance on the outer side of the anterior lobe, and not extending into the medullary matter. Fallot mentions an instance of suffocation from charcoal vapour, where a little coagulated blood was found between the layers of the arachnoid membrane of the cerebellum in the region of the left occipital hollow.[[2104]] Three instances of extravasation are enumerated in a list of German cases analysed by Dr. Bird.[[2105]] Such appearances might be expected more frequently, considering the manifest tendency of this kind of poisoning to cause congestion in the head.—The blood is generally described as being liquid and very dark. But M. Ollivier has lately called attention to the fact, that the blood both before and after death is not unusually more florid in the veins than natural.[[2106]] In a case mentioned by M. Rayer globules of an oily-looking matter were found swimming on the surface of the blood and urine.[[2107]] This is a solitary observation.—The body usually remains flaccid, and the customary stage of rigidity is imperfect. In some instances, however, as in those related by Dr. Schenck, the stage of rigidity is passed through in the usual manner. It is not uncommon to find vomited matter lying beside the body, a circumstance which may naturally mislead the unpractised. This is represented by Professor Wagner of Berlin to have occurred uniformly in his experience;[[2108]] and it is also mentioned in many of the cases reported by others;[[2109]] but it is not invariable.—A red appearance in the stomach and intestines has been noticed in many cases,[[2110]] and often ascribed to inflammation; but it is probably nothing more than the result of the venous congestion, which pervades most of the membranous surfaces of the body.