240 Messrs. Dakin, Cohen, Daufresne, and Kenyon. 



Determination of Germicidal Action. — The antiseptic action of the 

 substances referred to in the Table was characterised by determining the 

 minimal concentration of a solution capable of killing in two hours at the 

 temperature of the laboratory the organisms under investigation, suspended 

 either in water or in serum. The technique was as follows : 



A series of tubes each containing 5 c.c. of a solution of the substance at a 

 progressively decreasing concentration is first of all prepared, and to each tube 

 one or two drops of a 24-hour-old culture of the organism in peptone 

 bouillon is added. A blank experiment with 5 c.c. of distilled water with a 

 drop of the culture is also made. The mixtures of substance and microbes 

 are carefully shaken every half hour and remain at a temperature of 

 18-20° for two hours. A loop full of the contents of each tube is then taken 

 and added to a series of tubes, each containing 3 c.c. of bouillon, which are 

 then incubated for 24 hours at 37°. When no growth appears in these inocu- 

 lated tubes, the concentration of the antiseptic in the first series of tubes is 

 judged sufficient to kill the organisms. Incomplete sterilisation is indicated 

 by growth, and the necessary concentration for sterilisation can be determined 

 more closely by subsequent repetitions at less widely varying strengths of 

 solution. 



The tests carried out in the presence of blood serum were performed in the 

 same way, only the liquid contained in the first series of tubes contained 

 50 per cent, of horse serum previously heated to 55-56°. One drop of 

 culture was added for every 2 c.c. of the serum mixture. 



Action of Gldoramines on Amino-acids. — The chloraniine employed in these 

 experiments was usually ^-toluene sulphochloramide. When an aqueous 

 solution of this substance is added to a solution of an amino-acid, p-toluene 

 sulphonamide is rapidly precipitated, and a pungent odour, probably due to a 

 chloramino-acid, is noted. On standing or on warming the solution, carbon 

 dioxide is rapidly evolved through the decomposition of the chloramino-acid, 

 and an aldehyde is formed. In the following experiments equimolecular 

 quantities of the amino-acid and toluene sulphonamide in water were mixed 

 and then distilled. 



Glycine gave formaldehyde, which was characterised by its nitrophenyl- 

 hydrazone, M.P. 181°, by conversion into hexamethylenetetramine on 

 evaporation with ammonia, and by various colour reactions. 



Glycine anhydride behaved similarly to the above. 



Alanine gave acetaldehyde, which was identified by conversion into the 

 nitrophenylhydrazone, which, after crystallisation from alcohol, melted at the 

 correct temperature, 130°. The Kimini reaction with sodium nitroprusside 

 and piperidine was strongly positive. 



