168 ANTISEPTICS 



100 parts by weight of phenol, and they recommend the following method 

 of standardising: To 5 c.c. of a particular dilution of the disinfectant 

 add 5 drops of a 24-hour-old bouillon culture of the organism (usually 

 b. typhosus), which has been incubated at 37 C. Shake the mixture 

 and make subcultures every 2 minutes to 15 minutes. Perform a 

 parallel series of experiments with carbolic acid, and express the 

 comparative result in multiples of the carbolic acid doing the same 

 work. 



The Action of Antiseptics. In inquiries into the actions 

 of antiseptics attention to a great variety of factors is necessary, 

 especially when the object is not to compare different antiseptics 

 with one another, but when the absolute value of any body is 

 being investigated. Thus the medium in which the bacteria to 

 be killed are situated is important ; the more albuminous it 

 is, the greater degree of concentration is required. Again, 

 the higher the temperature at which the action is to take 

 place, the more dilute may the antiseptic be, or the shorter the 

 exposure necessary for a given effect to take place. The most 

 important factor, however, to be considered is the chemical 

 nature of the substances employed. Chick has shown that the 

 action of a disinfectant upon a bacterium presents close 

 analogies with the interaction of simple chemical substances, 

 such as an acid and an alkali. In the case of anthrax spores, 

 during the first few minutes a great fatality occurs, after which 

 the action of the antiseptic gradually tails off. With certain 

 other organisms, however, such as the paratyphoid bacillus, 

 the presence in a culture especially in a young culture of 

 highly resistant forms renders the initial action of an antiseptic 

 less marked. The action of an antiseptic, like the action of an 

 acid and an alkali, is very much increased by raising the 

 temperature ; from which follows the practical conclusion that, 

 in any disinfection, the use of warm solutions is advisable. 

 Chick and C. J. Martin have further investigated the fact that 

 the presence of albuminous material in a mixture of disinfectant 

 and bacteria decreases the action of the disinfectant, and 

 consider that the latter is adsorbed by the albumin. They have 

 shown grounds for believing that a disinfectant in an emulsion- 

 ised form is more efficient than a similar disinfectant in actual 

 solution, because of a similar phenomenon occurring ; for, 

 just as a disinfectant may be put out of action by being 

 adsorbed by organic particles, so when these organic particles 

 happen to be bacteria, the adsorption process causes a greater 

 concentration of the antiseptic round the bacterial protoplasm, 

 and thus hastens its death. 



Though nearly every substance which is not a food to the 



