(see Encycl.) is a subject on which much has been written to very little purpose. Of all the attempts which have been made to account for it, there is not one that can be thought satisfactory. This, however, is not perhaps a matter of great importance, if a method could only be discovered to stop the progress of contagion where it is known to have place. Among the many benefits which may be reaped from the late discoveries in Chemistry, even this desideratum promises promises to be one; and we surely need not add one of the greatest. Dr James Carmichael Smyth, physician extraordinary to his Majesty, suggested, in the year 1795 or 1796, a process for determining the effect of the nitric acid in destroying contagion; and experiments, according to his directions, were made on board the Union and other ships at Sheerness.
The Union was an hospital ship, and the experiment on board her was conducted by Mr Menzies, late surgeon to his Majesty's sloop Discovery, and by Mr Balfour, surgeon of the Union; and when it was considered, that fresh contagion was daily pouring into the hospital from the Russian vessels, which were at that time lying in the Downs, and which had brought with them a species of fever that might in every sense of the word be termed an epidemic, it will be allowed, that the success which attended it was such that it cannot be too generally known.
The wards were extremely crowded, and the sick of every description lay in cradles, promiscuously arranged, to the number of nearly two hundred; of which, about one hundred and fifty were in different stages of the above malignant fever, which was extremely contagious, as appeared evident from its rapid progress and fatal effects among the attendants on the sick and the ship's company.
The utensils and materials provided for the process were the following: A quantity of fine sand, about two dozen quart earthen pipkins, as many common tea-cups, some long slips of glass to be used as spatulas, a quantity of concentrated vitriolic (sulphuric) acid, and a quantity of pure nitre (nitrat of potash).
The process was conducted in the following manner:
All the ports and scuttles were shut up; the sand, which had been previously heated in iron pots, was then scooped out into the pipkins by means of an iron ladle; and in this heated sand, in each pipkin, a small tea-cup was immersed, containing about half an ounce of the sulphuric acid, to which, after it had acquired a proper degree of heat, an equal quantity of nitrat of potash in powder was gradually added, and the mixture flamed with a glass spatula till the vapour arose from it in considerable quantity (a). The pipkins were then carried through the wards by the nurses and convalescents, who kept walking about with them in their hands, occasionally putting them under the cradles of the sick, and in every corner where any foul air was suspected to lodge. In this manner they continued fumigating, until the whole space between decks was fore and aft filled with the vapour, which appeared like a thick haze.
The vapour at first excited a good deal of coughing among the patients, which gradually ceased as it became more generally diffused through the wards: part of this effect, however, was to be attributed to the inattention of those who carried the pipkins, in putting them too near the faces of the sick; which caused them to inhale the strong vapour as it immediately issued from the cups.
The body-clothes and bed-clothes of the sick were, as much as possible, exposed to the nitrous vapour during the fumigation; and all the foul linen removed from them was immediately immersed in a tub of cold water, afterwards carried on deck, rinsed out, and hung up till nearly dry, and then fumigated before it was taken to the wash-house: a precaution extremely necessary in every case of infectious disorder. Due attention was also paid to cleanliness and ventilation.
It took about three hours to fumigate the ship. In about an hour after, the vapour having entirely subsided, the ports and scuttles were thrown open for the admission of fresh air. It could plainly be perceived that the air of the hospital was greatly sweetened even by this first fumigation. The process was repeated again next morning; and the people employed, being now better acquainted with it, were more expert, and finished the whole in about an hour's time. In an hour afterwards, the vapour having entirely subsided, the fresh air was freely admitted into the hospital as before. Fewer pipkins were employed for the evening fumigations than for those of the mornings, as the fresh air could not be admitted so freely after the former as the latter.
The pleasing and immediate effect of the fumigation in destroying the offensive and disagreeable smell, arising from so many sick crowded together, was now very perceptible, even to the nurses and attendants; the consequence of which was, that they began to place some degree of confidence in its efficacy, and approached the cradles of the infected with less dread of being attacked with the disorder: so that the sick were better attended, and the duty of the hospital was more regularly and more cheerfully performed. In short, a pleasing gleam of hope seemed now to cast its cheering influence over that general depondency, which was before evidently pictured in every countenance, from the dread and horror each individual naturally entertained of being, perhaps, the next victim to the malignant powers of a virulent contagion.
It is a remarkable fact, that from the 26th of November 1795, when the fumigation was first resorted to, till the 25th of December, not a person on board was attacked with the fever, though, in the three months preceding, more than one third of all the people in the ship had been seized with the distemper, and of these more than one in four were carried off by it; and the probability is, that the sickness and mortality would have gone on, increasing in proportion to the diffusion of the contagion, and to the increasing depondency of the people, who considered themselves as so many devoted victims.
The advantage of the fumigation was not felt by the ship's company and attendants alone, whom it prevented from the baneful effects of the fever: the sick and convalescents derived almost an equal benefit from it. The symptoms of the disease were meliorated, and lost much of their malignant appearance; and the advantage of a pure
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(a) That the fumes of the mineral acids possessed the property of stopping contagion was proved by Moreau as far back as the year 1773, who, by means of the fumes of muriatic acid extracted from the muriat of soda (sea salt) by the sulphuric acid, purified the air of the cathedral of Dijon, which had been so much infected by exhumations that they were obliged to abandon the building. See Chemistry, no 426, in this Supplement. Great confidence is always dangerous. It proved so on the present occasion. On the 17th of December they imagined themselves secure, that they discontinued the custom of fumigating morning and evening, thinking that once a day was sufficient. On the 25th, one of the nurses suffered a flight attack; and on the 26th, a marine, who, for a week before, had been in a state of intoxication, was seized with the fever, of which he died. These two accidents gave immediate alarm; they returned again to the practice of fumigating twice a day; and from that time to the extermination of the disorder, there was not an instance of a person suffering from contagion on board the ship.
The success of the experiment was not confined to the Union: the power of the nitrous vapour to destroy contagion was equally displayed on board the Russian ships in which it was employed. The safety, too, with which it may be employed, in any situation, without inconvenience or risk of fire, is another great recommendation in its favour.
From the description that has been given of the process, no person can be at any loss in resorting to the same kind of fumigation. It is only necessary to observe, for the sake of those who may not be versed in chemical pursuits, that the ingredients ought to be pure, and that metal vessels or rods must not be employed. Any kind of metal getting among the ingredients would cause the vapour to be very noxious instead of salutary. The fumes that rise should be white; if they are of a red colour, there is reason to suspect the purity of the ingredients.
The importance of this discovery need not be insisted on: it is equally applicable to every species of putrid contagion, even to the plague itself. It should therefore be used in all hospitals and parish workhouses; and should be constantly resorted to by the proprietors of all large works, on the first appearance of infectious disease among the people employed in them:—indeed, it should be employed even as a preventive in all situations where a number of people, from the nature of their business, are obliged to be crowded together, or where, from local circumstances, there are reasons for supposing that the purity of the air is injured by noxious exhalations or other causes. If there be any circumstances in which its utility may be called in question, it can only be in cases of inflammatory diseases; for, in such, super-oxygenation has been found hurtful.
CONTRA-HARMONICAL Proportion, that relation of three terms, in which the difference of the first and second is to the difference of the second and third, as the third is to the first. Thus, for instance, 3, 5, and 6, are numbers contra-harmonically proportional; for \( \frac{2}{1} : \frac{6}{5} \).