PHYSICAL AND CHEMICAL AGENTS 37 



the crude acid being considered a more effectual 

 disinfectant than the more refined grades. Carbolic 

 acid does not corrode metalsj and " in a 5jper cent 

 solution will destroy all vegetative bacteria and 

 most^ spores even in the presence of considerable 

 organic matter." (Jordan.) Its germicidal pqweris 

 great ly 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 crespls are substances contained in crude 

 carbolic acid which are used very satisfactorily in 

 surgical work, the best-known preparations being 

 creoUnj 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. 



Spa^s 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 



