26 Dr. Henry' s/uriher Experiments on the 



temperatures varying from 200° to 206°, and applied to a 

 girl aged thirteen years. On the 30th of November, no effect 

 having been produced, another waistcoat was substituted, 

 which had been worn eleven hours by Johnston on the third 

 day of the efflorescence, and then disinfected by a tempera- 

 ture of 20t° applied during two hours. No symptoms of 

 scarlatina have shown themselves in this case. 



In all the foregoing instances, it was ascertained by the 

 most careful inquiries that the children, to whom the disin- 

 fected waistcoats were applied, had never been affected with 

 scarlatina, and were therefore liable to that disease. The 

 children were attentively examined every day, in order that 

 no slight symptom might pass unobserved*. 



The experiments, which have been related, appear to me 

 sufficiently numerous to prove, that by exposure to a tempera- 

 txire not belo'do 200° Fahr. during at least one hotit; the con- 

 tagious matter of scarlatina is either dissipated or destroyed. 

 To me it seems more probable that it is decomposed, than that 

 it is merely volatilized ; because cow-pock matter, though com- 

 pletely deprived of its volatile portion at 120°, is not rendered 

 inert by temperatures much below HO". I did not, however, 

 consider it as either necessary to the proof, or justifiable, to 

 determine, with respect to the contagion of scarlatina, either 

 the lowest temperature, or the shortest time, adequate to the 

 disinfecting agency; for these points, which are of no practi- 

 cal importance, could not have been decided without the ac- 

 tual communication of the malady. Still less necessary, and 

 less justifiable, should I have thought it, to have proved, by 

 exciting the disease, that, the waistcoats, as taken from the 

 patients, were impregnated with the contagion of scarlatina. 



It may, I am aware, be urged that the induction woud 

 have been more satisfactory, if founded on a greater number 

 of instances. But experiments, of the kind which have been 

 related, are attended with so many difficulties, as to forbid 

 their multiplication beyond what is absolutely necessary. Not 

 to mention other obstacles, it is far from easy to find young 

 persons in every respect unexceptionable for the purpose; — 

 to insulate them, as was done in these instances, from all 

 casual sources of infection; — and to keep them under the 

 watchful care of observers, qualified to mark even indistinct 

 symptoms that might arise, and to apply the proper remedies. 

 It must be acknowledged also, that the inference from the 



• It is due to Mr. Edward Johnson, resident clerk of the Manchester 

 House of Recovery, that I should acknowledge his valuable assistance, 

 especially in the care with which he superintended the disinfecting pro- 

 cesses. 



destructible 



