EXPERIMENTS ON DISINFECTION. 
585 
free exposure of an infected room to the air by allowing the 
windows to stay open several days is not enough to disinfect 
it. This has been practically proved at the Charite Hospital 
after scarlet fever and measles, in several instances. 
The second series of experiments was made by Dr. Wernich 
of Breslau, in the chemical laboratory of the Berlin Patho¬ 
logical Institute (Centralblatt Med. Wiss ., No. 13, 1877), 
upon the disinfecting power of sulphurous acid and of dry 
heat. The method adopted consisted in preparing an 
“ infecting material ” by steeping woollen thread, pieces of 
linen rag, and cotton wool, previously proved to be free from 
atmospheric organisms, in putrid solutions of feces or meat, 
and gently drying them. These substances were then tested 
for their capability of producing bacteria by means of the 
modified Pasteups fluid above mentioned, which consisted 
of distilled water 100 parts, cane sugar 10 parts, ammonium 
tartrate, 0*5 part, and 0T part potassium phosphate. This 
solution was freshly prepared before each set of experiments, 
filtered, boiled for half an hour, and immediately poured 
into the test glasses and preserved with the usual precau¬ 
tions. To test the effect of disinfection, the wool or wadding, 
after exposure for a definite time to a definite degree of heat 
in an oven, or to a measurable volume of sulphurous acid 
in a bell-glass, was immediately transferred to the Pasteups 
fluid, and the efficacy of the disinfectant was estimated by 
the rapidity of development of bacteria, if such appeared, or 
by their complete absence, as indicated by the fluid remain¬ 
ing perfectly cloudless. It was thus found that 83 percent, 
of sulphurous acid by volume failed even after many hours 
to prevent the development of bacteria, but that if the 
amount of gas reached from 4*0 to 7T5 per cent, by volume 
of the contents of the bell-jar, and the process had gone on 
for at least six hours, no bacteria at all developed. On the 
other hand, while exposure to a temperature of 110° to 118° 
Cent, even for twenty-four hours failed to destroy the 
bacterial germs, five minutes' exposure to one of 125° to 150° 
Cent, invariably succeeded, and the test fluid remained clear 
even for eleven days or longer. Dr. Wernich specially re¬ 
minds us that his results must not be taken as applicable 
to all forms of bacteria, some of which probably require 
severer measures for their complete destruction. He also 
points out that it is easier to disinfect wool than linen, and 
that cotton wadding is the most difficult of all to free from 
infectious germs .—Medical Times and Gazette. 
