Oct. is, 1920 Germicidal Value of Some Chlorin Disinfectants 109 



The results shown in Table XX indicate that the results previously 

 obtained were too high, presumably because in the previous experiments 

 there was no attempt to neutralize the disinfectant. However, on the 

 addition of ammonia there is still evident a great increase in germicidal 

 activity and much less decrease in germicidal power when organic matter 

 is present. 



A selective action upon the different types of organisms was also seen. 

 Where the concentration of available chlorin was low and the time of 

 exposure comparatively short the plates were overgrown by spreaders 

 and various types of colonies, of which the anthrax colonies made a very 

 small part. With greater concentration of chlorin and longer exposure 

 this proportion was reversed, and most of the colonies seen were those 

 of anthrax. In experiment 38 it was found that even after no anthrax 

 colonies were to be found there were still spreaders and colonies of organ- 

 isms other than anthrax. These organisms were not identified except 

 to make sure they were not anthrax but were evidently already present 

 on the hide and were more resistant than the strain of anthrax spores 



employed. 



CONCLUSION 



(1) In the ordinary routine work of general disinfection, such as dis- 

 infection of cattle cars and pens, there is always a large amount of organic 

 matter present. It is evident, therefore, that because of the enormous 

 diminution in germicidal value on addition of organic matter as well as 

 because of the injurious effects on metals and fabrics the chlorin dis- 

 infectants as a class do not seem to be suited for use under the usual 

 conditions and by the usual methods of general disinfection. That is not 

 to say, however, that when properly used they are not efficient and 

 valuable in the treatment of infected wounds; in fact, the evidence 

 available goes to show that they are of great value when so used; and, of 

 course, chlorin and hypochlorites are being very widely and success- 

 fully used for the disinfection of drinking water. 



(2) Compared on a basis of weight of chloramin T as against weight 

 of chlorin as sodium hypochlorite (Dakin's solution) or hypochlorous 

 acid (eusol), or as chlorin in aqueous solution, chloramin T is less efficient 

 than the others. But if the comparison is made on the basis of available 

 chlorin contained it is much more efficient against Staphylococcus aureus, 

 much less efficient against Bacillus pyocyaneus, and approximately equal 

 in efficiency against B. typhosus. 



(3) The experiments upon Bacillus tuberculosis indicate that the 

 chlorin disinfectants are worth very little so far as that organism is 

 concerned. This is not surprising in view of the use of antiformin 

 (NaOCl + NaOH) in isolating tubercle bacilli. 



(4) In the present work, considered as a whole, there is seen throughout 

 more or less "selective action" on the part of the various disinfectants. 

 The most clearly defined example of this is seen in the extremely high 



