DISINFECTING PROPERTIES OF CARBOLIC ACID. 
683 
This gives us a 2 per cent, solution of the acid, which was 
used throughout the first series of experiments. 
As soon as possible after the bouillon culture was added, 
with a sterilized dropping pipet, one drop of the acid solution 
containing the organisms was transferred to 10 cc. of distilled 
sterilized water, and the water well shaken. With the same 
pipet after it was sterilized in a Bunsen flame, one drop was 
transferred from the water to 10 cc. of nutrient agar, and the 
agar plated according to the Koch method. Cultures were 
also made after five and ten minutes exposure to the acid. 
The control plate was made by adding to 24 cc. of dis¬ 
tilled sterilized water, 1 cc. of the same bouillon culture used 
in the acid solutions, and the same dilution carried out. By 
this method it is easy to see that only the merest trace of acid 
is transferred to the agar plate with the organisms. The 
dropping pipet dropped fifty-two drops to the cc , therefore 
!the acid would be present on the agar plate 1:13,520,000. Not 
enough to inhibit the growth of the organisms that were not 
destroyed by the action of the acid. 
Throughout these experiments there will be noticed cer¬ 
tain minor irregularities, that is, occasionally there is found 
more colonies on a plate made after ten minutes exposure to 
the acid than on one made after five minutes. This is ex¬ 
plained in no other way than that we are dealing with a me¬ 
chanical suspension of solid particles in a solution, and one 
irop of this solution may contain a great many more germs 
Tan another, or clumps may be formed containing a very 
arge number of germs. In the latter case it would require 
onger exposure to the acid to kill all the germs. 
In these experiments I did not filter the bouillon culture, 
is A. C. Abbot did in his work, with corrosive sublimate, but 
lsed it just as the germs grew in the tube by only shaking it 
veil just before it was used to distribute the germs through 
he bouillon as evenly as possible ; and then if any clumps 
xisted they would be exposed to the acid under conditions 
nore similar to those met with in the disinfection of wounds. 
The staphylococcus pyogenes aureus was used in most of 
hese experiments, because it is the germ against which our 
