86 DISINFECTANTS 



An extensive study of the mechanism of mercuric 

 chloride disinfection was made by Gegenbauer (1921). 

 He found that HgCL is not only adsorbed on coagulated 

 serum proteins, but that it is also dissolved in them, and 

 that it can be washed out again. Besides, an insoluble 

 mercury proteinate is formed which cannot be washed 

 out, but the normal protein can be restored upon the 

 addition of H2S which forms HgS. Gegenbauer then 

 applied these findings to Staphylococci. When the cells 

 had remained for an hour in a solution which contained as 

 much as 2% HgCL, they would grow if repeatedly washed 

 with water. But after 2 hours of exposure they could 

 not usually be revived by washing. However, when the 

 antidote HgS was applied, bacteria from a 2% HgCU so- 

 lution could be brought back to life after 6 hours, but not 

 after 11 hours. With 0.1% HgCL, the cells became viable 

 upon HoS treatment even after 36 hours. The results are 

 shown in Figure 19. 



According to Gegenbauer, the actual poisonmg pro- 

 ceeds in three stages: first, the bichloride of mercury 

 dissolves fairly rapidly in the protoplasm of the Staphy- 

 lococci and probably interrupts all cell functions. This 

 proceeds according to a definite partition coefficient. 

 Then a slower process begins, the formation of a mer- 

 cury proteinate. While the first process can be reversed 

 by washing, the proteinate cannot be removed by wash- 

 ing, and after about 2 hours, its formation has gone so 

 far that in every cell some vital protein has been changed. 

 This process, however, becomes reversible on the addi- 

 tion of H2S, though only within a limited time. There- 

 fore, we must assume a third reaction, namely the de- 

 struction of some essential life function. Either some 

 catabolic process is accelerated by mercury, or the mer- 

 cury proteinate itself may undergo a further change 

 which is irreversible. The rate of this third process is 

 approximately proportional to the square root of the 

 mercury concentration. 



