On the other hand, many facts are known, which are adequate for the refutation of these statements, and that are sufficient to put the case beyond a doubt. Small-pox propagates by a contagious poison, eliminated from the blood, and found in the pox or pustule. It is known to every one that it affects, by contact, hence the practice of inoculation, which is nothing more than the inserting, under the skin, a little of that agent, a practice which has been in use among the negroes of Africa, since, or before, the introduction of the doctrines of Mahomet. Many physicians, perhaps almost all, believe that it, the poison, may be diffused through the air, and in that situation produce its wonted effects; but evidence is submitted to shew, how questionable that is: and it is conclusive, as far as negative evidence can go. The following experiment was performed by Dr O’Ryan of Lyons.[2] The force of its results, and their tendency, cannot be overlooked. Footnote 2: O’Ryan, Sur les Fievres. “A dish containing lint saturated with matter taken from the natural and the inoculated small-pox, was placed upon a table, whose diameter was three feet, and children who never had the disease, and never were inoculated or vaccinated, were placed around it, and kept there for some considerable time; yet none of them were seized with the disease.” “He also exposed children within two feet of a child affected at the time with the inoculated small-pox, for an hour daily, for fourteen days. None of the children were affected, and all were successfully inoculated two months afterwards.” We are acquainted, too, with many cases of small-pox, where the houses in which they were, were visited by many persons, some of whom had not been vaccinated, or inoculated, and yet the disease did not spread to them; and in those instances, where the distemper did spread, only some, and not all, who were liable, were affected, as would have been the case, had the matter been inserted under the skin.