404 



Mr. W. H. Pendlebury and Miss M. Seward. 



As soon as all was ready the time of the first reappearance of 

 the blue colour was noted, then a drop of thiosulphate was intro- 

 duced as described, and the next appearance of colour was noted. 



Table B. 



The value of each of the thiosulphate drops, in standard iodine 

 solution was then determined. 



The equivalent of one drop is 6'05 c.c. of this solution, containing 

 0*00248 gram iodine per c.c. Now 1 millionth-gram-molecule of 

 potassium chlorate liberates 7*62 millionth-grams in weight of 

 iodine. 



Therefore the number of millionth -gram -molecules of potassium 

 chlorate decomposed in each cubic centimetre of the mixture per 

 minute is 



6-05x0-00248 

 762 x 792 x 1-64 



= 0-01512 mgm. 



The quantities taken of the reacting substances represented 



HC1 20 X 65-11 m.g.m. per c.c. 



KC10 3 30x51-5 



Scheme of the Paper. 



In describing the results of our investigations we shall first con- 

 sider the action of hydrogen chlorate on hydrogen chloride and 

 examine the effect of variation of the former acid on the rate of 

 change ; we next consider the effect of variation in hydrogen chloride 

 on such a mixture. We then consider and examine the effect of in- 

 troducing potassium chloride into the mixture of the two acids, and 

 from the results thereby obtained we gain considerable help in our 



