Oct. is, 1920 Germicidal Value of Some Chlorin Disinfectants 



91 



Table IV. — Comparative germicidal efficiency of chloramin T and Dakin's solution 

 against Staphylococcus aureus, Bacillus pyocyaneus, and B. typhosus, in the presence 

 of 50 per cent blood serum — Continued 



Experiment 7 — continued 



EXPERIMENT 8 



Chloramin T: 



1 to 200 



1 to 300 



1 to 400 



1 to 500 



1 to 600 



1 to 800 



1 to 1,000 



Dakin 's solution : 



NaOCl 1 to 200 



NaOCl 1 to 300 



NaOCl 1 to 400 



NaOCl 1 to 500 ... . 



NaOCl 1 to 600 ... . 



NaOCl 1 to 800 ... . 



NaOCl 1 to 1,000. .. 



+ 



+ 

 + 



No test. 

 Do. 



No test. 

 No test. 



4- 

 + 



Experiments 9, 10, and ii. — These experiments were undertaken to 

 determine the efficiency of chloramin T and Dakin's solution against 

 Staphylococcus aureus, Bacillus pyocyaneus, and B. typhosus without the 

 addition of blood serum. They are in contrast with the three preceding 

 experiments, in which 50 per cent of blood serum was used. 



The technic was as follows: Two drops of a 24-hour bouillon culture 

 were added to 5 cc. of disinfectant, and the mixture was well shaken. 

 After intervals of 1 hour and 2 hours, 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 results are given in Table V. 



In the results shown in Tables IV and V there is seen evidence of what 

 may be called "selective" action on the part of the two disinfectants 

 tested. For instance, the amount of chloramin T required to kill Staphy- 

 lococcus aureus is very much less than that required to kill Bacillus pyo- 

 cyaneus. In like manner in the presence of blood serum it requires more 



