1879.] 



Researches in Chemical Equivalence. 



185 



quantities of nickelous and cobaltous solutions were then carefully 

 measured out, mixed, and the temperature observed. 10 cub. 

 centims. of sodic hydrate were then added, the solution stirred 

 vigorously, and the temperature again observed. The precipitate was 

 then filtered off as quickly as possible (an aspirator being used to 

 facilitate the filtration), and washed, first with cold and then with 

 hot water. Three days' intermittent washing was required to free the 

 precipitate from the undecomposed nickelous and cobaltous salts, 

 cobaltous hydrate having, as is well known, a powerful attraction for 

 cobaltous sulphate, thereby forming a basic salt. After washing, the 

 precipitate was converted into sulphate by treatment with hydric 

 sulphate, and weighed. The mixed sulphates were then dissolved in 

 water, and separated by Gibbs's method, the nickelous sulphate being 

 weighed, and the cobaltous sulphate obtained by difference. It was 

 found that a small quantity of sodic sulphate was always present in 

 the precipitate, the washing having failed to remove it, and this 

 required to be estimated and deducted. For this purpose the 

 nickelous sulphate, after being weighed, was dissolved in water, and 

 the nickel precipitated w 7 ith baric hydrate. The barium in the 

 filtrate was then removed with hydric sulphate, and the filtrate con- 

 taining the sodic sulphate evaporated to dryness and weighed. The 

 results obtained are comprised in the following table. 























us sal 



us sal 

 n. 



03 -p 



s 3 



al 



tate. 



us sal 

 tated 



us sal 

 ated. 



us sal 

 taled 

 d.) 



|| 

 "p. * 





i- a 



o « 











— 'a. 





la 





II 

 5 o 



Nicke 

 ta 



Cobal 

 ta 



Cobal 

 taken 



H 3 



09 



Nicke 

 , preci 



Cobal 

 preci 



If! 



Sodic : 

 preci 



Tempi 



5? * 



grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



grm. 



arm. 



o o 





1 



•9 



•8093 



•9155 



•1050 



•8105 



•7198 



•0105 



7-8 



I 



"2 



•8 



•7*81 



•8667 



•1980 



•6687 



•6268 



•0110 



6-7 



11 



•3 



•7 



•6268 



•8980 



■2765 



•6215 



•5483 



•0135 



7-8 



III 



■4 



•6 



•5598 



•8650 



•3510 



•5140 



•4738 



•0105 



7-8 



IV 



■5 



•5 



•4363 



•8885 



•4465 



•4420 



•3783 



•0090 



7-8 



V 



•6 



•4 



•3613 



•8-35 



-5295 



•3340 



•2953 



•0150 



7-7-5 



VI 



•7 



3 



•2808 



•84J0 



■5825 



•2615 



•2423 



•0110 



7 — 7 5 



VII 



•8 



•2 



•1408 



•8840 



•7080 



•1760 



•1168 



0130 



8-8-5 



VIII 



•9 



•1 



•0483 



•8765 



•7865 



•0900 



■0383 



0105 



7 — 7 "5 



IX 



In this table the precipitates are all returned as sulphates. The 

 total possible amount of normal sulphate attainable with the constant 

 quantity of soclic hydrate employed having been '8248 grm., we are 

 able to calculate the entire composition of the precipitate thus : — From 

 its total weight, the amount of sodic sulphate is first subtracted ; from 

 the residue the constant quantity '8248 ; the remainder, which is the 

 cobaltous sulphate carried down with the hydrate, is deducted as a 

 correction from the cobaltous sulphate originally taken and that 

 which was precipitated, it having no share in the reaction we had to 

 examine. Under "temperature" we give the temperatures of the 



