70 



J. Bhaduri — Transformation of 



[No. 2, 



the apparatus had to he modified. In one form the solution of chlorate 

 and pieces of cal^ite were introduced into the hulh and then a thin 

 test tube filled with hydrochloric acid and sufficiently narrow to 

 pass through the mouth, was introduced. The apparatus was 

 adjusted, and then slightly inclined to allow the acid to decompose 

 the chlorate, &c. In the second form, pieces of calcite were 

 introduced in the leading tube and the chlorate in the bulb, both being 

 held in a horizontal position. The acid was then rapidly introduced 

 and immediately afterwards the stopper was replaced, the apparatus 

 being still in horizontal position. The other end was then introduced 

 into the absorption bulb and the whole apparatus made vertical. The 

 results obtained by these methods are perfectly concordant, but the 

 second method is more expeditious than the first. The quantity of acid 

 must be in excess (about 5 c.c. strong hydrochloric acid for 2 to 3 c.c. of 

 potassium chlorate solution). When marble was used, the small quant- 

 ity of chlorine which oxidised the " ous " iron to " ic " iron was calculated 

 and added to the available oxygen. The liberated iodine was transferred 

 to a porcelain dish, and titrated by thiosulphate standardised by solid 

 iodine purified by Stas's method. 



1 c.c. Thiosulphate = 0'01272 gm. Iodine. 



Number of experiment. 



I. 



II. 



III. 



IV. 



V. 



Weight of KC10 3 solution used 

 Vol. of strong HC1 added 

 Vol. of Thiosulphate required 



2'5 gms. 

 5 c.c. 

 31 25 c.c. 



2"5gms. 

 5 c.c. 

 31-15 c.c. 



3 gms. 

 5 c.c. 

 37-3 c.c. 



3 gms. 

 5 c.c. 

 37-4 c.c. 



3 gms. 

 5 c.c. 

 37-3 c.c 



Mean 



31 



2 





3733 





Hence 1 gm. of KC10 3 = 1248 c.c. of thiosulphate solution from I 

 and II, and 12-44 c.c. from III, IV and V. Thus taking 1246 as the 

 mean the amount of available oxygen = 12-46 x "01272 x r f r = 0-01002 

 gm. The actual quantity of available oxygen = 001 gm. Hence all 

 the three methods gave equally accurate results and preference was 

 given to one or the other, as circumstances required. 



Estimation of hypochlorites. 

 Hypochlorous acid as well as hypochlorites can be estimated in 

 exactly the same way as chlorates. In this case ferrous sulphate and 

 not the double salt should be used, as a part of the ammonia might 

 be completely decomposed liberating free nitrogen, thus causing a loss 

 of chlorine. Chlorates may be expected to liberate nitrogen, but my 

 own experiments prove that no such decomposition actually takes place. 



