TOXICOLOGY AND PHARMACOLOGY 395 



Microorganisms. 



Microorganisms occur more or less densely in their media as 

 millions of minute dots, rods or threads. They constitute a dis- 

 persed phase and as such obey the physical laws to which all suspen- 

 sions are subject. Collectively they possess an enormous develop- 

 ment of surface; and, consequently, surface attraction especially 

 influences those substances that are dissolved by them (in other words, 

 more as the substance diminishes the surface tension of water) . 



Should our assumption that adsorption plays an essential part in 

 disinfection be correct, then the same substance will be a much better 

 disinfectant in aqueous solution than when dissolved in alcohol or in 

 acetone. 1 This assumption is sustained by such investigations as 

 have been undertaken. According to ROBERT KOCH, anthrax spares 

 were not destroyed by the application for 100 days of 5 per cent car- 

 bolic acid in oil nor by 5 per cent carbolic acid in alcohol for 70 days, 

 whereas they were destroyed after 48 hours' .exposure to 5 per cent 

 aqueous solution of carbolic acid. Anthrax baccilli were of undirnin- 

 ished virulence after 2 days' treatment with 5 per cent carbolic acid in 

 oil, whereas 1 per cent aqueous solution killed them in 2 minutes. 

 Moreover, according to REICHEL,* the distribution of the phenol 

 between albumin and the oil (as compared with water) is in favor of 

 the oil. 



According to the researches of PAUL and KRONIG, as well as those 

 of SHEURLEN and K. SPIRO, phenol acts in disinfecting as a molecule 

 and not as an ion. Sodium carbolate which is strongly dissociated 

 has a much weaker action than phenol. Phenol is less dissociated 

 in alcohol than in water, so that if it were merely a question of 

 dissociation, phenol should be a better disinfectant in alcoholic than 

 in aqueous solutions. As is shown by the following data taken from 

 PAUL and KRONIG'S paper, the facts are quite the reverse. Anthrax 

 spores were treated with the disinfectant, according to the marble 

 method, and then sown on agar; the resulting colonies were counted. 



Number of 

 colonies. 



4 per cent carbolic acid in water 1505 



4 per cent carbolic acid in alcohol oo 



We thus see that in disinfection adsorbability from water is more 

 important than solubility. 



1 In disinfecting the hands and skin, alcohol and alcoholic solutions and even 

 acetone are almost exclusively used, though entirely different factors are of im- 

 portance in determining their use (better capacity to wet the fatty epidermis, the 

 shrinking action of alcohol and deeper penetration into the capillary spaces of the 

 skin (BECHHOLD)). 



