116 Disinfecting Powers of Increased Temperatures. 
fore 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 suffi- 
ciently numerous to prove, that by exposure to a temperature not below 
200° Fahr. during at least one hour, the contagious matter of scarla- 
tina 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 completely deprived of its volatile portion at 
120°. is not rendered inert by temperatures much below 140°. 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 practical im- 
portance, could not have been decided without the actual communi- 
cation of the malady. Still less necessary, and less justifiable, 
should Ihave thonght it, to have proved, by exciting the disease, 
that, the waistcoats, as taken from the patients, were Wh ha Sri 
with the contagion of scarlatina. 
It may, I am aware, be urged that the induction would have 
been more satisfactory, if founda on a greater number of instances. 
But experiments, of the kind which have been related, are attend- 
ed 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 symp- 
toms that might arise, and to apply the proper remedies. It must be 
acknowledged also, that the inference from the destructible nature’ 
of the fomztes of scarlatina, to that of other contagions, remains ana- 
logical; and that experiments are still wanting to extend the proof 
to other known species. ‘The argument, however, in its nature cu- 
mulative, has acquired a great increase of probability by the step 
which has been made, in showing that the power of heat is not 
merely exerted over cow-pock infection, but extends to the active 
and virulent contagion of scarlatina. 
* Jt is due to Mr. Edward Johnson, resident clerk of the Manchester House of 
Recovery, that I should acknowledge his valuable assistance, especially in the 
caré with which he superintended the disinfecting processes. 
