Dr. Smith in the dissertation above mentioned observes, that “it may be doubted whether any moral cause would be sufficient to protect, for a long period, an unaccustomed resident in a marshy situation from the usual consequences.” This is no doubt very probable but, from the example of Lord Macartney’s attendants in China, it appears equally probable that it makes little difference whether the country be marshy or not. Dr. Lind has many excellent observations upon the subject of unhealthy countries, and gives particular directions for strangers how to act, when obliged to expose themselves to the inclemencies of the weather; but none of these being effectual in preventing the access of the true pestilence, we must still adhere to the old Latin adage already quoted, p. [302]. Flight seems to be the most effectual method. To avoid migrations to those countries where it usually rages, and, if it were possible to persuade the inhabitants of such countries, to imitate the example of Chinese industry, instead of allowing the greater part of the territories they possess to lie waste, would in all probability gradually lessen both the frequency and violence of this terrible disease. Migrations of large bodies of people, especially for the purposes of war, are greatly to be dreaded. If a few Englishmen, possessed of every thing necessary, could not keep their health at Pekin, what must have been the probable consequence of landing an army of an hundred thousand, with a view to conquest? Or what could we expect if the Chinese were to “pour forth by millions” into other countries in order to conquer them? Dr. Lind takes notice that even of the first Portuguese adventurers to Africa, such as escaped the first sickness continued afterwards to enjoy good health. He likewise observes that many who left Britain, after being seasoned to the countries to which they went, chose rather to remain abroad for life, than to run a new risk by going back to their own country. It is not therefore so much the greater unhealthiness of the country to which we go, as the change, which is to be dreaded. If therefore great bodies of men will employ themselves in constant rambling from one country to another, no wonder that diseases break out among them, unknown, either in the countries they have left, or those to which they go.
We come now to the third mode of prevention, viz. that of destroying the infection after it has begun to exist. This is varied according to the nature of those things which we suppose to be infected. The general notion of infection taking place in the atmosphere has been already spoken of; but the uncertainty of this hypothesis, and the apparent impossibility of altering a constitution of the atmosphere, must certainly leave very little room for hope in this case. It hath, however, been attempted by various methods. Hippocrates adopted the opinion that all diseases were produced by the air, and from him it was borrowed by Lucretius, as we are informed by the annotator on Creech’s Translation of that author. “In his book de Flatibus (of winds) says the annotator, after a long narration of the effects that the air produces, he at length falls on the subject of diseases, all of which he affirms to be bred and generated in the bodies of animals by means of the air. First (says he) I will begin with the most common fevorous disease, which accompanies, in a manner, all diseases whatever. For there are two sorts of fevers, one that is promiscuous, and common to all, and is called the plague; the other, by reason of unhealthful diet, is peculiar only to such as use that diet; but of both these kinds of fevers the air is the sole author and cause, for the common fever or plague happens alike to all, because they all breathe the same air; and it is certain that the like air, being alike mingled in like bodies, must beget like fevers.” In consequence of his theory, this great physician advised to have recourse to fire as a purifier of air in times of pestilence. But experience doth not warrant the success of this method; neither indeed can we suppose that it could be successful, unless people were able to kindle such fires as would absorb the whole atmosphere of a country. This method was tried in London without the least success; nay, seemingly with bad effect; for, the very night the fires were lighted, more than four thousand people died; and, a few days after, an end was put to the experiment by such violent rains as extinguished all the fires at once.
The burning of infected clothes has already been taken notice of; but though this must certainly prevent any new infection from arising from these clothes, it will not prove that the infection may not evaporate during the time of burning, and, being volatilized even beyond its natural pitch, by the heat, may do mischief at a greater distance than could have happened had they been let alone. The instance, formerly quoted from Dr. Huxham, of the small-pox being disseminated by the smoke of burning infected clothes, if not a proof, affords at least a strong presumption, of the danger of such a practice. The only way of perfectly ensuring safety in such a case would be to burn them by the sea-side, when the wind blows from the shore. Were the smoke allowed to pass over land, and great piles burnt at once, it is impossible to say how far the contagion might be carried.[121]
Another mode of purification is by exposing suspected goods to heat, to the vapour of vinegar, &c. fumigating with gun-powder, sulphur, &c. and on this principle various powders of fumigation have been invented; some of which are said to have been very successful in Russia; and the composition of one is given by Dr. Alexander Russel in his Natural History of Aleppo; but all these are undervalued by Dr. Guthrie,[122] who calls the practice of fumigation or smoaking, an “inadequate and ineffectual ceremony.” Dr. Mitchel, also discommends them, saying that they are advised “without any proof that these destroy pestilential matter, and while, at the same time, it is certain that they diminish more or less the wholesomeness of the atmosphere with which they are mingled.”[123] Of late the vapours of pure nitrous acid (the nitric, according to the new nomenclature) has been recommended, with the boldest appeal to experience; but the consideration of this naturally belongs to the second part of this work, where we shall have occasion also to consider the theory of the septic acid. In the mean time we must go on with some farther account of the different modes of fumigation.
“There is no better corrective (says Allen from Diemerbroeck[124]) of a pestilential air, than fire; as much experience has taught us. Hippocrates subdued and extinguished that famous plague, which came amongst the Grecians from Ethiopia; for he commanded great fires to be kindled throughout the whole city, especially in the night time, to purge away the pollutions of the air. It is believed that a fire made with juniper-wood or ash, tends much to correct the venomous corruptions of the air. The kindling of sulphur and gun-powder purify the air, and drive away its corruptions; so does the burning of amber, pitch, frankincense, &c. so do the fumes of vinegar raised with red-hot irons, or bricks.” According to Etmuller, “Hippocrates drove away that famous plague in Greece by the use of sulphur; the fumes of it are very much commended to correct the air, and make drink more wholesome; it prevents all manner of corruptions and alterations, as well as the putridinous alteration of the blood. In a great degree of malignity, the shirt and clothes may be impregnated with the fume of sulphur.”
Here we have accounts of a disease, called that famous plague, driven away by two different methods; and, to complete our dilemma, Dr. Canestrinus tells us that the plague at Athens is said to have been staid “by sprinkling the streets with wine.” What an expensive remedy, when the odour of privies was afterwards found to answer as well! “Whilst the plague was raging at Oczakow, an earthquake[125] happened on the very day that it began to decline. In this case did any vapour issue from the earth destructive of the pestilential contagion? or did former noxious exhalations cease in consequence of the convulsion of the earth?[126] Sorbait relates, that, in the time of the vintage in the neighbourhood of Moselle, the plague ceased like a miracle, while the must was in a fermenting state. At Vienna likewise it was observed that, during and at the close of the vintage, the disease manifestly declined; which may have been owing to the great quantity of fixed air in the atmosphere.”
To this our author adds, that “places adjoining to spice-shops have generally remained free from infection; and, in the plague of London, all those employed in shipbuilding escaped the disease. Smiths also and cooks remained uninfected.” M. Volney tells us that, in Egypt, water-carriers are exempted; and Baldwin, that oilmen are in the same happy predicament; while on the other hand Allen quotes Boerhaave saying, that “Forestus, Diemerbroeck, the French, English, and Germans, observed, that all dealers in soap, washers, and all who by their business used soap, nay, who only wore shirts washed with soap, presently died of the plague.”
From so many and so discordant opinions, the only conclusion we can draw is, that, when once a pestilence has invaded a country, there is not any possibility of operating upon the contagion in such a manner as to destroy it. If the plague ceases, it must do so naturally, and we cannot accelerate this cessation. This is entirely conformable to the opinion of Dr. Patrick Russel. Speaking of the decline of the plague at Marseilles, and the vigorous exertions of the magistrates to put a stop to it, he says, “The causes now enumerated might no doubt have some effect, but a more powerful and general cause had begun long before to restrain the havock of the pestilence, which had declined visibly in the month of September, and in those of October, November and December declined with a rapidity not ascribable to the exertions of the most vigorous police. This cause is generally supposed to be some change in the constitution of the air; but which has hitherto been defined with no better success than that peculiar state of the atmosphere which, in conjunction with contagion, is absolutely necessary to render the plague epidemical.”
Dr. Russel takes notice of the methods of extinguishing contagion already mentioned, by kindling fires, &c. and disapproves of them. We shall not therefore spend more time in considering whether or not there is any probability of eradicating or mitigating the violence of a plague when once it is introduced. However this may be impracticable in so large a space, it seems that it certainly may be done in smaller spaces, ships for instance; or, if not with the true plague, at least with malignant and infectious fevers. Dr. Trotter, in his Medicina Nautica, has laid down methods for accomplishing this, and expresses the highest confidence in their success. He adopts the doctrine of contagion, of which he gives the same definition that in this treatise is given of infection, viz. “Something propagated from diseased bodies, or from substances that have been in contact with them, producing a similar disease in other persons[127]—the propagation of contagion, as well as its reception into the healthy body. A more aggravated degree of malignity will generate a greater quantity of infection, and, as it may be confined in a larger or smaller space, it will be less or more noxious. A fever may be called malignant, when, with the symptoms of debility, there is a cadaverous smell arising from the body, an unusual fœtor of the breath, stools, and other excretions, the tongue black and parched, the eye dusky or yellow, the countenance bloated and dejected, and the skin sallow. In approaching a sick bed of this kind, a person not much accustomed to such visits will be very liable to receive the infection; and the unpleasant smell will be much sooner perceived than by the physician or other attendants. We conclude that a malignant typhus is more apt to generate contagion, because slight cases are found not to extend to others, even though no mode of precaution has been used. The disease itself is incapable of generating infection, till after a certain period; but this period is uncertain: it seems to depend on the nature of the symptoms, whether they are mild or malignant. We are assured of this fact, from a timely separation having prevented the farther progress; and by this means ALONE, I apprehend, we eradicate contagion in SHIPS, or ANY WHERE ELSE. In the small-pox[128] the disease seems incapable of infecting another person before the second or third day of the eruption. With the measles it is otherwise. The disease may be propagated at the most early stage of the eruption; and, if I was to be allowed to conjecture on the subject, I would say, that the contagion is the offspring of the catarrh (the cough and hoarseness resembling a cold) which accompanies the measles.
“Substances imbued with the exhalations from infected bodies, if not exposed to the air, have their powers of communicating the disease increased; or, in other words, the infection from fomites (infected cotton, clothes, &c.) is said to become more virulent than it was when first separated from the body.