DISINFECTANTS 87 



3.0% 



to 



0.029 



Fig. 19. Relation between the concentration of HgCK'. and the time 

 during which staphylococci can be exposed to that disinfectant and 

 still recover. The curve at the left indicates the limits of recovery after 

 washing, the curve at the right, the limits of recovery after use of H2S 

 as antidote. Abscissa: time in hours, on logarithmic scale; ordinate: 

 percent concentration on logarithmic scale. (From data of Gegenbauer, 

 1921.) 



Many organic mercury compounds have been tested in 

 the hope of finding disinfectants which are less toxic and 

 less irritant to mammals than the bichloride. Some of 

 these newer disinfectants are in fact more powerful than 

 the bichloride against bacteria and relatively less toxic 

 to the hosts. Their use, however, is not as general as 

 that of the inorganic compounds, because the properties 

 of the organic radicals affect the chemical behavior of 

 the compounds. This is exemplified in the great de- 

 pendence of the effect of mercurochrome upon the acidity 

 of the substrate (a phenomenon which is typical of all 

 dyes and therefore is not surprising in mercurochrome). 



Other organic mercury compounds are highly selec- 

 tive, like metaphen, merthiolate and phenyl-mercuri-ni- 

 trate. These three compounds are stronger disinfectants 

 than the bichloride of mercury — mercurochrome is not. 



The organic mercury compounds have no mercury ions, 



