. Manchester Memoirs, Vol. Hi. (1908), No. 14- 3 



mentary character, appear to be worth placing on 



record. 



Description of Method used. 



The method as described by Dr. Bailey is as 



follows : — 



The following solutions are required : — 



A. Potassium iodide (KI), 20 grams to litre. 



B. Sulphuric acid (H2SO4), ir85 grams to litre. 



C. Sodium thiosulphate 



127 c.c. to decolourise 10 c.c. D, i.e., 

 I c.c. = 1 mgm. iodine. 



D. Centinormal iodine {\'2'j grams, iodiiie dissolved 

 in potassium iodide solution, and made up to i litre). 



10 c.c. each of A and B are placed in a 2oz. bottle on 

 a white porcelain plate 6 inches square, and completely 

 exposed, i.e., any obstruction x feet high must not be 

 nearer than x yards from the bottle. 



The records are ultimately calculated to indicate 

 mgms. iodine liberated per 100 c.c. of solution A per hour. 

 Preliutitiary Experiments. 



It was necessary in the first place to examine the 

 influence of various factors which might be supposed to 

 affect the method abnormally under the conditions met 

 with in the tropics. 



Effect of Temperature. 



The first of these factors is evidently temperature, as 

 this may easily rise in tropical sunlight to considerably 

 over 100° Fahr. 



It was found, however, that on keeping the ordinary 

 mixture, made as above, for 12 hours in an incubator 

 at 97° Fahr., only a negligible quantity of iodine (0*5 mgm.) 

 was liberated. It may be concluded, therefore, that the 

 reaction is practically unaffected by temperature under 

 the ordinary conditions of exposure. 



