288 J. T. Norton, Jr.— Influence of Hydrochloric Acid 



shows that the influence of the hydrochloric acid upon the 

 thiosulphate depends chiefly upon the amount of the thio- 

 sulphate present and afterwards upon the degree of dilu- 



Table I. 



Yolume of 

 liquid at 



beginning of 

 titration. 



cm 8 . 



100 

 200 

 300 

 400 



500 



100 

 '200 

 300 

 400 

 500 



100 

 200 

 300 

 400 

 500 



Na 3 S 2 8 

 approximately 



iV 



Volume of — iodine used in titration. 

 10 



10 



HCl=none. 



30 

 a 



n 



a 



25 



20 



(C 



a 

 u 



30*25 

 30-22 

 30-20 

 30-21 

 30-20 



25-29 

 25-28 

 25-29 

 25-27 

 25-22 



20-15 

 20-20 

 20-21 

 20-20 

 20-10 



| meanrr 

 V30-22 



1 

 | mean: 



^25-27 



| mean: 

 V20-15 



= 1 cm 3 . 

 cm 3 . 



30-75 

 30-21 

 30-22 

 30-20 

 30-20 



25-32 

 25-34 

 25-41 

 25-24 

 25-23 



20-17 

 20-13 

 20*15 

 20-10 

 20-10 



:5 cm 3 . =10 cm 3 

 cm 3 . cm 3 . 



30-76 

 30-56 

 31-03 

 30*20 

 30-21 



25*98 

 25-40 

 25-38 

 25-30 

 25-40 



20-33 

 20-27 

 20-20 

 20-27 

 20-17 



31-2 



31-4 



30-9 



30-55 



30*55 



25-70 

 25-45 

 25-83 

 25-63 

 25-30 



20-23 

 20-23 

 20*17 

 20-07 

 20-13 



tion and its own absolute quantity. Thus when 30 cm3 of 

 sodium thiosulphate were employed the effect of I0 cm3 of acid 

 is marked at all dilutions within the range of the experiments ; 

 the effect of 5 cm3 of acid is inappreciable only at a dilution of 

 from 400 to 500 cm3 , and when l cm3 of acid is employed the 

 effect is only perceptible at a volume of 100 cm3 . When 25 cm3 

 of the thiosulphate were used the influence of the acid is less 

 marked ; for at a dilution of 500 cm3 the effect of 10 cm3 of acid 

 is not seen, and 20 cm3 of the thiosulphate may be present at 

 any dilution down to 100 cm3 in the presence of as much as 10 cm3 

 of the acid, and even considerably more, as experiments not 

 included in the table indicated. 



The slight discrepancies which appear occasionally in the 

 table were due, no doubt, to unavoidable differences in the 

 time of action. 



This influence of time upon the reaction between sodium 

 thiosulphate iodine and hydrochloric acid comes out clearly in 

 the following series of experiments, in which the thiosulphate 

 was run into the acidified water, cooled to a temperature of 

 from to 5° C. by means of ice, the solution being allowed to 



