When the scab is prematurely rubbed off (a circumstance not unfrequent among children and working people), the application of a little aqua lythargyri acet. to the part immediately coagulates the surface, which supplies its place, and prevents a sore.

In my former treatises on this subject I have remarked that the human constitution frequently retains its susceptibility to the smallpox contagion (both from effluvia and contact) after previously feeling its influence.  In further corroboration of this declaration many facts have been communicated to me by various correspondents.  I shall select one of them.

“Dear sir: 

“Society at large must, I think, feel much indebted to you for your Inquiries and Observations on the Nature and Effects of the Variolae Vaccinae, etc., etc.  As I conceive what I am now about to communicate to be of some importance, I imagine it cannot be uninteresting to you, especially as it will serve to corroborate your assertion of the susceptibility of the human system of the variolous contagion, although it has previously been made sensible of its action.  In November, 1793, I was desired to inoculate a person with the smallpox.  I took the variolous matter from a child under the disease in the natural way, who had a large burthen of distinct pustules.  The mother of the child being desirous of seeing my method of communicating the disease by inoculation, after having opened a pustule, I introduced the point of my lancet in the usual way on the back part of my own hand, and thought no more of it until I felt a sensation in the part which reminded me of the transaction.  This happened upon the third day; on the fourth there were all the appearances common to inoculation, at which I was not at all surprised, nor did I feel myself uneasy upon perceiving the inflammation continue to increase to the sixth and seventh day, accompanied with a very small quantity of fluid, repeated experiments having taught me it might happen so with persons who had undergone the disease, and yet would escape any constitutional affection; but I was not so fortunate; for on the eighth day I was seized with all the symptoms of the eruptive fever, but in a much more violent degree than when I was before inoculated, which was about eighteen years previous to this, when I had a considerable number of pustules.  I must confess I was now greatly alarmed, although I had been much engaged in the smallpox, having at different times inoculated not less than two thousand persons.  I was convinced my present indisposition proceeded from the insertion of the variolous matter, and, therefore, anxiously looked for an eruption.  On the tenth day I felt a very unpleasant sensation of stillness and heat on each side of my face near my ear, and the fever began to decline.  The affection in my face soon terminated in three or four pustules attended with inflammation, but which did not maturate, and I was presently well. 
      “I remain, dear sir, etc.,
          “Thomas miles.”