Certain then it is that variolous matter may undergo such a change from the putrefactive process, as well as from some of the more obscure and latent processes of nature, as will render it incapable of giving the smallpox in such a manner as to secure the human constitution from future infection, although we see at the same time it is capable of exciting a disease which bears so strong a resemblance to it as to produce inflammation and matter in the incised skin (frequently, indeed, more violent than when it produces its effects perfectly), swelling of the axillary glands, general indisposition, and eruptions.  So strongly persuaded was the gentleman, whose practice I have mentioned in page 56 of the late treatise, that he could produce a mild smallpox by his mode of managing the matter, that he spoke of it as a useful discovery until convinced of his error by the fatal consequence which ensued.

After this ought we to be in the smallest degree surprised to find, among a great number of individuals who, by living in dairies, have been casually exposed to the cow-pox virus when in a state analogous to that of the smallpox above described, some who may have had the disease so imperfectly as not to render them secure from variolous attacks?  For the matter, when burst from the pustules on the nipples of the cow, by being exposed, from its lodgment there, to the heat of an inflamed surface, and from being at the same time in a situation to be occasionally moistened with milk, is often likely to be in a state conducive to putrefaction; and thus, under some modification of decomposition, it must, of course, sometimes find access to the hand of the milker in such a way as to infect him.  What confusion should we have were there no other mode of inoculating the smallpox than such as would happen from handling the diseased skin of a person labouring under that distemper in some of its advanced and loathsome stages!  It must be observed that every case of cow-pox in the human species, whether communicated by design or otherwise, is to be considered as a case of inoculation.  And here I may be allowed to make an observation on the case of the farmer communicated to me by Dr. Ingenhousz.  That he was exposed to the matter when it had undergone the putrefactive change is highly probable from the doctor’s observing that the sick cows at the farm gave out an offensive stench from their udders.  However, I must remark that it is unusual for cattle to suffer to such an extent, when disordered with the cowpox, as to make a bystander sensible of any ill smell.  I have often stood among a herd which had the distemper without being conscious of its presence from any particular effluvia.  Indeed, in this neighbourhood it commonly receives an early check from escharotic applications of the cow leech.  It has been conceived to be contagious without contact; but this idea cannot be well founded because the cattle in one meadow do