PHYSICAL AND CHEMICAL AGENTS 37 



the crude acid being considered a more effectual 

 disinfectant than the more refined grades. Carbolic 

 acid does not corrode metals, and " in a 5 per cent 

 solution will destroy all vegetative bacteria and 

 most spores even in the presence of considerable 

 organic matter/' (Jordan.) Its germicidal power is 

 greatly increased by heat, experiment showing that 

 at room temperature a 5 per cent solution was not 

 effective against anthrax spores in thirty-six days, 

 while at 55 C. (131 F.) it was successful in two 

 hours, and at 75 C. (167 F.) in three minutes. 



The cresols are substances contained in crude 

 carbolic acid which are used very satisfactorily in 

 surgical work, the best-known preparations being 

 creolin, crenosol, and lysol. 



Alcohol is much used as a disinfectant in surgical 

 work, although of doubtful value, and is also used for 

 the preservation of organic substances. 



Soaps of all kinds are disinfectant and antiseptic. 

 It has been demonstrated that a 10 per cent solution 

 of good soap would destroy the bacilli of typhoid 

 fever, a stronger solution being necessary for cholera 

 bacilli ; but for pus germs, streptococci and staphylo- 

 cocci, a 20 per cent solution was entirely ineffective. 



For practical purposes, however, a soap solution 

 could not be the sole disinfectant used for the bed 



