Doctor Henry, of Manchester, has, in a late paper, published some most interesting experiments, upon the disinfecting power of heat. He found that the vaccine virus was deprived of its infecting quality, at 140 deg. of Farenheit, and that the contagions of Scarlatina, and Typhus fever, from fomites, were certainly dissipated and destroyed, at the dry heat of boiling water. In regard to these last, he might surely have ventured to fix the standard of safety at a greatly lower temperature; for if the grosser vaccine matter could be rendered inert at 140 deg., there can be little doubt of the subtile gaseous emanations, which constitute the aerial contagions, being dissipated by the same agent, at an inferior degree. In the absence of direct experiment, we may venture to infer, that 120 deg. would suffice, to nullify these last. Such, at least, has been the belief of those, who have been employed to purify ships, barracks, and hospitals, from contagion, and I should think it must have been founded on experience.[34] [Footnote 34: As far back as the years 1796-7-8, this fact was familiar to us in the St. Domingo war, only we were satisfied with a minimum heat of 120 deg., from a belief that a temperature of that height, as it coagulated the ova of insects (the cock roach for instance), and was otherwise incompatible with insect life, would avail to dissipate contagion.] He does not treat of the disinfecting property of light, although such an agent was well worthy of his notice; for the power, which in closely stopped bottles can deprive Cayenne Pepper of its sting--render our Prussic Acid as harmless as cream, and convert the strongest medicinal powders into so much powder of _post_, can also avail to destroy the matter and principle of Contagion. In fact, no other is used for purifying goods, at our Lazzarettoes, where suspected articles of merchandise, after some nugatory fumigations, are simply exposed to light and air with such certain effect, that there is not, I believe, in this country, any record of infection being propagated from them afterwards. The experiments of Doctor Henry are as simple and beautiful in themselves, as they promise to be useful and important, for now even the horrible contagion of hospital gangrene would appear to be under the controul of the pure agent he has been describing; and the principle now established of light and heat, the grand vivifying powers of the creation, being the sure and true preservers of the creature, man, from the poisons generated even by himself, and otherwise around him, calls for our admiration and gratitude, as shewing that these agents and emanations of Almighty power can be made, in the hands of the practical philosopher, to serve the purposes of domestic science, and in as far as we can see, to fulfil, at least in that respect, the best intentions of the Creator. WINDSOR: PRINTED RY R. OXLEY, AT THE EXPRESS OFFICE. Transcriber's Note