Small-pox is always produced by its own specific con tagion ; and when once the individual has gone through the disease, in however slight a degree, he is secured from any future attack. Upon this fact is founded the practice of inoculation; for we learn, that where a por tion of the matter is inserted under the cuticle, it will communicate a much milder disease than one that is received in the usual way, which is probably by the lungs. 'We are, however, totally unable to explain the cause of this difference. The relation which the fever bears to the eruption, or the degree in which one is to be regard ed as the cause of the other, is a point that has given rise to much speculation. According to the humeral pathology, the eruption was thought to afford a remark able example of the critical discharge of an offending matter from the system; and, proceeding upon this principle, the great object of the practitioner was sup posed to be, to promote this discharge ; a system which led to a practice precisely the reverse of the true one, and which must no doubt have proved highly destruc tive. In what way the fever operates, or what is the proximate cause of the disease, we know not ; but it appears that the eruption is the consequence of the fe ver, and that, whatever diminishes the fever diminishes the eruption, and at the same time lessens the violence and danger of the disease. Our general plan of treat ment is accordingly founded upon this principle, to di minish the febrile action of the earlier stages by the ge neral application of the antiphlogistic plan, especially by purgatives and by external cold, and in some cases, where the inflammatory tendency is considerable, by blood-letting. In the distinct variety this may be re garded as comprehending the whole of the treatment ; For it would appear, that all direct attempts to act upon the eruption, except so far as we can subdue the fever, are at least useless, if not positively injurious. Tonics and stimulants are seldom indicated, or only in conse quence of some unusual occurrence ; and when the dis ease has run through its course, the powers of the con stitution soon return to their accustomed standard.
In the confluent Small-pox we have a much more for midable diseasmto combat, and one which, unfortunate ly, but too of,ten baffles all our endeavours. From its very commencement it exhibits symptoms that have so much of the typhous appearance, as almost to deter us from the use of any active amiphlogistic treatment, and even purgatives and cool air appear to produce a dan gerous shock to the oppressed and languid powers of life. Still, however, they afford the only rational means of relief; but they must be pursued with caution, and under the constant inspection of some person who is well qualified to judge of their effects. The circum .tance which renders the practice, in this variety of the complaint, so critical, is, that when, from any cause, the eruption suddenly disappears—an effect which some -Imes ensues from the sudden application of cold to the :.nrface, or from the operation of a brisk purgative, the vital powers become suddenly oppressed in so great a degree, as to threaten the immediate extinction of life. When we suspect this to be the case, we are to apply external warmth, and to administer moderate doses of stimulants ; but this is to be done with caution, lest in this way we exasperate the violence of the febrile action. Sometimes, without any obvious cause, this deficiency of action ensues, when we are immediately to have recourse to the same means with those men tioned above. When the symptoms of variola assume the decided typhous type, and especially in the secon dary fever, it has been generally conceived that wine, bark, and other stimulants and tonics, are the appro priate remedies. We doubt how far this can be de
pended upon as a general mode of treatment ; but we apprehend that we are, in these cases, to proceed very much upon the same plan which has been already re commended in the latter stages of other malignant fe vers, of prescribing very much to obviate or palliate particular symptoms ; bearing in mind, that we have to contend, on the one hand, with a tendency to febrile excitement, and, on the other, with the state of ex haustion, which generally succeeds the former, when it has been violent and long protracted. There is often, in confluent Small-pox, a state of restlessnes, or extreme agitation, which is found to be alleviated by opium ; and although we do not expect any benefit to be de rived from sudorifics, we conceive that gentle diapho retics are often productive of great relief to the sensa tions, and, by removing a source of irritation, conspire with opiates in procuring sleep. One of the most dis tressing effects of confluent Small-pox, is the injury which it leaves to the constitution generally, or to par ticular organs, of which the eyes are the most apt to suffer, so as not unfrequcntly to produce the complete loss of sight.
The singular affection of Vaccinia has become an ob ject of great attention, in consequence of the remark able property which it possesses, of protecting the con stitution from the attacks of Variola ; and as it is, un der all its forms, a comparatively mild disease, and like wise possesses the peculiar advantage of being commu nicated only by absolute contact, it forms the means of securing the individual, without spreading any danger ous infection through the community at large.
The characteristics of Vaccinia are to produce a ve sicle of a circular form, with a depression in the centre, which makes its appearance in three or four days after the. insertion of the matter under the cuticle. On the eighth day it becomes filled with a transparent watery lymph ; which, about the tenth or eleventh, is convert ed into a dark coloured scab, and falls off, leaving a permanent mark on the part. Although the constitu tion receives so important a change by the disease, yet the general febrile affection is almost too slight to be observable ; and, except in some extraordinary cases, the only medical treatment which it requires is the ex hibition of a purgative at its termination. It was not to be expected, that so great an innovation in practice should be generally received without opposition ; but, whatever may have been the motives of the parties concerned, the results of all the controversies that have been carried on have been very fortunate ; for we have, by their means, had an opportunity of viewing the sub ject under every possible form, so as to arrive at a de gree of well-grounded confidence, which could not otherwise have been obtained. It is admitted, that there are cases where Small-pox has succeeded to Cow pox ; but they are of very rare occurrence ; perhaps not more so than a second attack of Small-pox, of which a few unequivocal cases are upon record : and it has, moreover, appeared, that the Small-pox which follows Cow-pox, has had its virulence so mitigated, as to be nearly without danger. We may farther add, that the accounts which were, at one period, so industriously propagated, of loathsome eruptions succeeding to Cow pox, are now considered to be altogether without foun dation.