412 Correspondence of J. Nickles. 
Reverting to the experiment with a supersaturated solution of sulphate 
of soda, we see it is the air adherent to the glass rod which determines the 
act of crystallization, since if the rod is heated to 100° C. no such result 
it th 
follows. Is it then the air which suffices for this action or some pecul- 
than air long undisturbed. 
this brings to mind that Schroeder and Busch have shown that fer- 
mentation is not caused by air filtered through cotton, and we now ask 
if the air rendered adynamic by the process of Hirn will not possess 
still more passivity. 
t is an argument more in favor of this theory now held by the advo- 
cates of spontaneous generation to know that it is not by germs. of 
infusoria suspended in the air that fermentation or putrefaction is carried 
on. These experiments appear to us to touch questions of the greatest 
importance in the sciences of observation, as well as others relating to the” 
most interesting considerations in cosmogony. 
_Empiricism.— Application of the Physical Sciences to Medicine.—A 
discussion which has recently taken place in the Academy of Medicine 
on the action of iron used as a medicine has made known to us this un- 
expected fact that there are physicians who deny any influence exercised 
by medicines in virtue of their chemical properties, and who think that the 
eral laws of matter which composes the universe) appears a penne? 
celebrated more than the rest, Dr. Trousseau, who raising the 
