STANDARDIZATION OF DISINFECTANTS 143 
organisms were not killed in fifteen days. A selective action was 
noticed. 
Quinone. Bactericidal activity of quinone has been found to be 
due to its chemical action on certain constituent proteins of the bacterial 
cell. According to Cooper quinone is a stronger bactericide than 
phenol, quinol, or acetone on account of its reactivity towards proteins 
in much lower eoncentrations. 
Dyes as Disinfectants. Recently it has been observed that dye- 
stuffs exert a distinct retarding action on bacteria. Churchman (1912) 
made one of the most important contributions to this question. He 
reported that gentian violet in dilutions of 1 to 100,000 when added to 
media would inhibit the development of certain bacteria. The Gram 
negative bacteria grew fairly well on the gentian violet media while 
generally the Gram positive would not. The subject has been greatly 
enriched by much recent work especially that of Krumwiede and his 
co-workers. Some of these researches are mentioned in other places. 
TaBLe IX 
SHOWING ANTISEPTIC VALUES OF SOME COMMON SUBSTANCES 
(After Park and Williams) 
Alum... .....0 cece eee 1 : 222 Mercurie chloride ....... 1 : 14,300 
Aluminum acetate. ...... 1 : 6000 Mercuric iodide ......... 1 : 40,000 
Boric acid. . ........05. 1:9 Potassium bromide....... 1:10 
Calcium chloride ...... . 1: 148 Potassium iodide. 1:10 
Calcium hypochlorite... .. 1: 25 Potassium permanganate.. 1 : 300 
Carbolic acid ........... 1 : 1000 Pure formaldehyde... 1 : 25,000 
Chloral hydrate.......... 1 : 333 Quinine sulphate......... 1 : 800 
Cupric sulphate.. ....... 1: 107 Silver nitrate. .......... 1 : 12,500 
Ferrous sulphate ........ 1 : 2000 Sodium borate .......... 1:14 
Formaldehyde ......... 1 : 10,000 Sodium chloride.......... 1:6 
Hydrogen peroxide....... 1 ; 20,000 Zinc sulphate,........05. 1: 20 
STANDARDIZATION OF DISINFECTANTS 
It is essential to know as far as possible just how toxic to the 
bacterial cell certain chemicals are. This knowledge is important in 
the purchase of large amounts of disinfectants and in their application 
to disinfection problems. That the chemical analysis would not 
furnish this information is apparent. Furthermore, many of the 
disinfecting compounds are of such complicated nature that a chemical 
analysis would be impossible. In view of these facts, many investi- 
gators have attempted to devise a purely bacteriological method since 
