An alarming accident has enabled me to test the value of one of my preparations on a living human subject--that subject being a man.
"My last letter informed you that I had resolved on making no further use of the Formula for recomposing some of the Borgia Poisons (erroneously supposed to be destroyed) left to me on the death of my lamented Hungarian friend--my master in chemical science.
"The motives which have led me to this decision are, I hope, beyond the reach of blame.
"You will remember agreeing with me, that the two specimens of these resuscitated poisons which I have succeeded in producing are capable--like the poisons already known to modern medical practice--of rendering the utmost benefit in certain cases of disease, if they are administered in carefully regulated doses.

Should I live to devote them to this good purpose, there will still be the danger (common to all poisonous preparations employed in medicine) of their doing fatal mischief, when misused by ignorance or crime.
"Bearing this in mind, I conceive it to be my duty to provide against dangerous results, by devoting myself to the discovery of efficient antidotes, before I adapt the preparations themselves to the capacities of the healing art.

I have had some previous experience in this branch of what I call preservative chemistry, and I have already in some degree succeeded in attaining my object.
"The Formula in cipher which I now send to you, on the slip of paper enclosed, is an antidote to that one of the two poisons known to you and to me by the fanciful name which you suggested for it--'Alexander's Wine.' "With regard to the second of the poisons, which (if you remember) I have entitled--in anticipation of its employment as medicine--'The Looking-Glass Drops,' I regret to say that I have not yet succeeded in discovering the antidote in this case.
"Having now sufficiently explained my present position, I may tell you of the extraordinary accident to which I have alluded at the beginning of my letter.
"About a fortnight since, I was sent for, just as I had finished my lecture to the students, to see one of my servants.

He had been suffering from illness for one or two days.

I had of course offered him my medical services.