DISINFECTING PROPERTIES OF CARBOLIC ACID. 
681 
So common is its use at present that no druggist, physician 
or surgeon is without it. A very large number of the disin¬ 
fecting preparations are partly composed of carbolic acid. Yet 
its disinfectant properties are questioned by some of the best 
modern medical men, some declaring it is not even an anti¬ 
septic. 
In my experiments with carbolic acid I have endeavored 
to demonstrate the proper amount of acid present in solution 
necessary to destroy germs, as well as to demonstrate the fact 
of its being a disinfectant. 
While the conditions in the laboratory are not the same as 
in disinfecting wounds, it is the. only way by which we are 
able to arrive at a satisfactory conclusion, for in disinfecting 
wounds we do not know the number of germs present, nor 
can we estimate the number of germs that survive the action 
of the acid. But in the method I have employed we are able 
to approximately estimate the number of germs exposed to the 
acid, also the number of germs that survive after exposure to 
the acid, at different lengths of time, which will be seen by 
the experiments. 
There are two general methods of testing a disinfectant. 
First: By using cultures dried on silk thread, etc. This 
is the method Koch used in his early work in testing disinfect¬ 
ants, but as it did not give satisfaction was discarded and is 
not used at present. But it merits a description. 
The threads are cut in short pieces, about an inch in length, 
and dipped in a solution containing germs, and are then dried, 
to make the germs adhere to the thread. 
Sterilized tubes containing the previously prepared threads 
are filled with solutions of the disinfectant of different con¬ 
centrations ; with a platinum wire these threads are fished out 
at the required time, and after removal of the disinfectant 
placed in culture media. The removal of the disinfectant is 
effected by washing in sterilized water and pressing between 
sterilized filter paper. But there are objections to this meth¬ 
od. It is hard to remove the disinfectant from the thread suf¬ 
ficiently enough to not inhibit the growth of the organisms 
that are not destroyed by its action. And we can not estimate 
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