DISINFECTANTS AND ANTISEPTICS. 2OI 



will sometimes kill the spores of anthrax after two days' 

 exposure (see Bacillus anthracis, Part IV.)- In the ab- 

 sence of spores the anthrax bacillus is destroyed by a I per 

 cent, solution in one hour. The less resistant pus cocci are 

 destroyed rapidly by a 2 per cent, solution. Combination 

 with an equal proportion of hydrochloric acid enhances the 

 efficacy of carbolic acid to a marked extent. This is due 

 to the prevention of albuminous combinations, thus allow- 

 ing- greater penetration of the disinfectant. 



Many other substances closely related to carbolic acid 

 are used and possess marked germicidal properties. 

 Among them may be mentioned creolin, cresol and lysol. 

 They are all slightly superior to carbolic acid in actual 

 germicidal value. 



Aniline Dyes. Many of these substances possess germ- 

 icidal properties, notably pyoktanin (methyl-violet). A 

 solution of 1-5000 will kill the anthrax bacillus in two 

 hours. A much stronger solution, 1-150, is required to 

 kill the typhoid bacillus in the same time. Malachite- 

 green is said to possess even greater germicidal value than 

 pyoktanin. Methylene-blue also possesses considerable 

 germicidal power.' 



Formaldehyde. A gaseous substance placed on the 

 market in a 40 per cent, aqueous solution. Remarkable 

 claims have been made for this substance, and numerous 

 investigations have shown it to possess, both in the liquid 

 and gaseous forms, wonderful disinfecting power under 

 certain conditions. It is a noticeable fact that the more 

 recent the investigation the lower the value placed upon it. 

 In solutions of i-iooo an exposure of twenty-four hours is 

 necessary to destroy the staphylococcus pyogenes aureus, 

 while 1-5000 is sufficient to restrain its growth (Slater 

 and Rideal). Its use in a gaseous form as a house-disin- 



