830 THE POPULAR SCIENCE MONTHLY. 



mate, benzoic acid and its salts, salicylic and metasalicylic acids, quinia, 

 many aromatic substances, and alcohol, have long been known as such. 

 Carbolic acid is the highest in repute among these poisons ; and it is 

 an interesting fact that Mr. E. Baumann has discovered this very sub- 

 stance among the products of the bacterian fermentation to which it 

 is so fatal. Alcohol is another substance similarly associated. The 

 discovery of the curious relations of these two substances gives a new 

 light upon the cause of the spontaneous destruction of bacteria in 

 strongly fermenting fluids, and encourages us to look for other sub- 

 stances having a similar origin and a like action. As evidence of the 

 possession of such properties by any substance, we should require 



1. That substances favorable to the development of bacteria should 

 remain free from them when the substance to be tested is added to 

 them. 



2. That active bacteria, when transplanted into a supporting mix- 

 ture to which a substance supposed to be poisonous to them has been 

 added, should cease to propagate themselves and die out. This may 

 be called the aseptic test. 



3. That, when the supposed poison is introduced into a solution 

 swarming with bacteria, all living examples should be killed. This 

 may be called the antiseptic test. 



Various aromatic substances, the products of fermentation, were 

 added to a mixture of water and chopped meat, at a temperature of 

 35 C They proved efficacious in preventing, suspending, or wholly 

 stopping decomposition in the following order, according to the strength 

 of their working : 



1. As Preventives of Decomposition : 



Indol in a proportion of 1 : 1,000 of the mixture. 



Kresol " " 2 : 1,000 " 



Phenylacetic acid, " " 2-5 : 1,000 " 



Carbolic acid ... . " " 5 : 1,000 " 



(The working of scatol and hydrocinnamic acid could not be satisfactorily as- 

 certained, on account of the difficulty of dissolving them in water.) 



2. As Aseptics killing transplanted organisms by poisoning the 

 supporting fluid : 



Scatol in a proportion of 0-4: 1,000 of the mixture. 



0-6:1,000 " 



Hydrociunamic acid 



Indol 



Kresol 



Phenylacetic acid . . 

 Carbolic acid 



0-6:1,000 

 0-8:1,000 

 1-2:1,000 

 5 : 1,000 



3. As Antiseptics wholly destroying all living bacteria : 



Scatol, in the proportion of 0-5 : 1,000 of the mixture, in twenty-four hours. 

 Hydrocinnamic acid, in a proportion of 0-8 : 1,000 of the mixture, in twenty- 

 four hours. 



