Oct. 15, 1920 Germicidal Value of Some Chlorin Disinfectants 



93 



Experiments 12 and 13. — These experiments were made for the pur- 

 pose of comparing the germicidal activity of chloramin T, Dakin's solu- 

 tion, and eusol against Staphylococcus aureus, Bacillus pyocyaneus, and 

 B. typhosus. 



The technic was as follows : Each dilution of the disinfectant was mixed 

 with an equal amount of a 24-hour culture of the test organism, and the 

 mixture was thoroughly shaken. After intervals of 10 minutes and 30 

 minutes, respectively, the mixtures were again shaken, and subcultures 

 were made with a 3-mm. platinum loop into tubes of standard bouillon 

 containing enough sodium thiosulphate to neutralize the disinfectant 

 carried over. The amounts of culture and disinfectant used were 2.5 

 cc. of each. For purposes of comparison, tests were made with mer- 

 curic chlorid, and in these tests sodium sulphid was used to neutralize 

 the disinfectant carried over. The results are given in Table VI. 



Table VI. — Comparative germicidal efficiency of chloramin T, Dakin's solution, eusol, 

 and mercuric chlorid against Staphylococcus aureus, Bacillus pyocyaneus, and B. ty- 

 phosus ° 



EXPERIMENT 12 



EXPERIMENT 13 



Chloramin T: 



1 to 1,000 



1 to 2,000 



Dakin's solution: 



NaOCl 1 to 2,000. . . . 



NaOCl 1 to 4,000 

 Eusol: 



HOC1 1 to 2,000. . . . 



HOC1 1 to 4,000. . . . 

 Mercuric chlorid: 



1 to 2,000 



1 to 4,000 



+ 

 + 



+ 

 + 



+ 



+ 

 + 



+ 



+ 



a + signifies growth; — , no growth. 



Experiments 14 and 15. — In these experiments the same disinfectants 

 were compared as in experiments 12 and 13, but with the addition of 

 blood serum. The technic was the same also, except that a mixture of 

 equal parts of blood serum and culture was used instead of culture alone. 

 The results are given in Table VII. 



