The powder is composed of eight grains of calomel, the same quantity of the compound powder of crabs claws, and one eighth part of a grain of emetic tartar. Instead of emetic tartar, I have sometimes substituted two grains of precipitated sulphur of antimony. In order to facilitate the division of the doses, a large quantity is prepared at once, and great care taken that the mixture is well performed. This quantity is usually sufficient for a healthy strong man; and the dose must be lessened for women or children, according to their age and strength, as well as for persons advanced in years. The first dose is commonly ordered at the commencement of the course, the second, three or four days after, and the third, about the eighth or ninth day; and I choose to inoculate the day after the last dose has been taken. On the days of purging, broths are allowed, and the patients are desired to abstain from unprepared vegetables. What has hitherto been said concerning the preparation, must be considered as proper only for the young or middle-aged, in a good state of health; but among those who are desirous of inoculation are often found tender, delicate, and weakly women, men of bad stamina, valetudinarians by constitution, by illness, or intemperance; also aged persons and children; and for these a very different treatment is directed; a milder course of medicine, rather of the alterative than purgative kind, is here preferable; and in many instances, an indulgence in some light animal food, with a glass or two of wine in case of lowness, is not only allowable, but necessary to support a proper degree of strength, especially in advanced age. Children whose bowels are often tender, and ought not to be ruffled by strong purges, yet require a mild mercurial, and bear it well; besides emptying the bowels of crudities, it is a good security against worms and their effects, which are sometimes of themselves perplexing enough, and produce very alarming and even fatal disorders. Indeed the particular state of health of every person entering upon the preparatory course, should be inquired into and considered. Inattention to this has, I am satisfied, done great mischief, and particularly the indiscreet use of mercurials, whereby a salivation has often been raised, to the risque of impairing good constitutions, and the ruin of such as were previously weak and infirm. The distinctions and treatment necessary, will be obvious to those who are acquainted with the animal œconomy and medical practice.