Under this division we include all those deleterious substances which can be administered through the medium of the atmosphere.
Those gases, the respiration of which occasions death by the negative operation of excluding oxygen, are not ranked under the class of poisons, for the history of such bodies involves physiological views peculiar to themselves, and belongs more correctly to the subject of suffocation, under which head it has already met with full consideration, vol. 2, p. 48.
Aërial poisons are of very undefined extent, and their history is involved in considerable obscurity. Every poison, capable of volatilization, may be admitted into the division; and even those substances which are generally regarded as fixed, may be mechanically suspended in the air, and thus produce their effects on the living system, through the medium of the lungs, stomach, or nerves. In the present state of our knowledge, we have, perhaps, only an imperfect idea of the distinction between a fixed and a volatile body. A very interesting paper on this subject was read before the Royal Academy of Berlin, by Professor Hermbstaed,[[497]] in which he observes that, generally speaking, we might consider all bodies as volatile, as it is most probable that, could we produce a sufficient degree of heat, no substance could resist it. The professor also states that many bodies, hitherto considered as fixed, are actually volatilized at the temperature of boiling water; such he found to be lime, baryta, strontia, and potass. We apprehend, however, that the professor has, in these instances, mistaken a phenomenon for volatility, which it is highly important to distinguish from it, viz. the elevation of a certain portion of a fixed body, by the carrying power of a vapour; thus, fixed oil may, in a minute proportion, be carried up with the steam of water. Certain bodies, however, which have been long considered as perfectly fixed at the ordinary temperature of the atmosphere, have been lately discovered to undergo a slow and almost imperceptible evaporation under such circumstances; and the discovery has led to a very satisfactory solution of several problems which were previously unintelligible. We shall adduce a striking exemplification of this truth, under the consideration of mercurial vapours.
The substances, included under the head of Aërial poisons, may be conveniently arranged in two orders, viz.
I. Those, whose particles exist mechanically suspended in the atmosphere.
II. Those, which are presented to us in a vaporous or gaseous form.
Of the first division the various arts will furnish ample illustration, as for instance the occupations of the colour-maker, plasterer, cotton-spinner, dry-grinder,[[498]] stone-cutter, hatter, furrier, miller, &c. &c. In all of which a subtle matter is given off, which becoming mechanically suspended in the air, penetrates the structure of the pulmonary organs, and excites disease, and even death.[[499]] In illustration of the second division, we have the trades of water-gilders, acid manufacturers, night-men, bleachers, and various others, many of which have been already noticed under the medical and chemical consideration of nuisances, vol. I, p. 330.
In the present chapter we cannot attempt an enumeration of every substance which may act as an aërial poison; we shall confine our attention to the history of a few bodies which are calculated to afford general elucidation, and are likely to become objects of forensic interest.
Mercurial Vapours.
It is not the least interesting fact in the history of aërial poisons, that substances, which are found to be extremely slow in their action, or even quite inert, when administered in their solid or liquid state, exert a very rapid and energetic operation when they are presented to the human body in the attenuated form of vapour. This fact is well illustrated by the subtlety and activity of metallic mercury in the state of vapour; a substance which, according to the highest authorities, is quite inactive when introduced in its grosser form into the stomach. It is thus that the workmen employed in gilding, silvering looking-glasses, constructing barometers, &c. experience such dreadful effects; that such effects arise from the metal in a state of vapour, and not, as some have supposed, from the oxide,[[500]] is a fact capable of demonstration, for the artists at Birmingham affix an apparatus in their chimneys as a system of economy, in order to collect the mercury, which is always found in its metallic state.[[501]] From the late interesting experiments of Mr. Faraday,[[502]] it appears that mercury rises in vapour at the ordinary temperature of the atmosphere; the knowledge of which fact will afford a very satisfactory explanation of several phenomena, which were previously unintelligible. Dr. Hermbstaed, in the memoir, above mentioned, “on the volatility of substances hitherto considered as fixed bodies,” relates the following curious fact with regard to the volatility of mercury. “At the Royal Manufactory of looking-glasses in Berlin, during a severe winter, the artificers who worked in a room, which had originally served for the process of silvering the glasses, lighted a fire, and thus heated the apartment to between 86° and 96° Fah. In a few days the whole of them were, to their great surprise, affected by a strong salivation, as there was no trace of mercury in, or near the room. They consulted on the subject, and suspecting the real cause of the event, had the flooring of the room taken up, when about 40 lbs of the metal were found spread about in different parts, where it had fallen at various times during the operation of silvering, which had been executed in that room before.” With such facts before us, we shall no longer be unable to explain the effects which were produced on board his majesty’s ship Triumph, off Cadiz, in April 1809, by the bursting of leathern bags containing quicksilver, and the consequent dispersion of not less than three tons of the metal through the vessel. The interest excited by this case has been very great, and as the facts, involved in its history, are of high medical importance, we were induced to apply for permission to search the journals of the ship; and, through the kindness of Dr. Burnett, one of his majesty’s commissioners for victualling the navy, and the assistance of Mr. Plowman, who held the situation of surgeon to the Triumph, we have been enabled to obtain a correct and detailed history of the event. Previous to the circumstances we are about to describe, “the ship’s company had been tolerably healthy, when unfortunately a quantity of quicksilver was received on board, and diffused over the ship in consequence of the bursting of the leathern bags, in which it had been enclosed; when its effects were soon displayed upon the crew, by occasioning ptyalism, partial paralysis, affections of the bowels; so that in three weeks, no less than two hundred men were in a state of salivation. In consequence of which two transports were taken up as hospital ships, in which the slighter cases soon recovered; but as many fresh cases occurred daily, Vice-Admiral Pickmore ordered a survey on the ship, and ship’s company, by the surgeons of the squadron, on the third of May, who reported the necessity of sending the ship into port, in order to clear her hold, change part of her provisions, into which the quicksilver had insinuated itself, and to purify her by means of ablution. This was accordingly done; but on stowing the hold afresh, every man so employed, as well as those engaged in the steward’s room, were attacked with ptyalism. Fresh cases happened daily, until they took their departure from Cadiz on the 13th of June; after which but few occurred, which was attributed by the surgeon to the coldness of the weather, the fresh breezes from the north-east, from the men having been kept constantly on deck, and not allowed to sleep on the orlop, and from not suffering those affected with ptyalism to lie on the lower deck; as well as from the constant attention paid in the ventilation of the ship by means of wind-sails. But, notwithstanding all these precautions, the ship had not been more than ten days at sea, when many of the men became worse, and it was found necessary to send twenty-four seamen on board the Goshawk, and two transports. On the arrival of the Triumph in Cawsand Bay, on the 5th of July, there did not remain one case of ptyalism on their list. During this extraordinary visitation two men died from excessive ptyalism, one of them at Cadiz, having previously lost his teeth, and both cheeks at the time of his decease being in a state of sphacelation; the other, who died at Gibraltar, had lost the whole of his teeth, two-thirds of his tongue, and, at the time of his death, the lower lip was in a state of gangrene. To the interesting facts above related, Mr. Plowman adds, that the interior of the ship was covered with a black powder, and that the copper bolts displayed the mercurial influence. The mercurial vapours proved fatal to the living stock on board, for nearly all the poultry, sheep, pigs, mice,[[503]] goats, cats, a dog, and even a canary bird, died from its influence.”