296 Analysis of Arsenical Nickel, 



soluble oxide of antimony. A second evaporation to dryness of 

 the soluble part, and re-solution in water, gave a further small 

 deposit of oxide of antimony, after wliich the solution was no 

 longer troubled by sulphuretted hydrogen. The whole of the 

 oxide of antimony weighed after calcination O'll parts, which, 

 subtracted from the weight of the arseniate of antimony, leaves 

 0'158 for the arsenic acid. 



The nitric solution, which had parted with the arseniate of 

 antimony by dilution with water, was then decomposed by sub- 

 carbonate of soda added in slight excess ; a pale apple-green 

 precipitate fell down, weighing after drying 1"030 parts; and 

 consisted of arseniated nickel with a small proportion of arseni- 

 ated cobalt. As a proof that this solution had parted with all 

 its arseniate of antimony, a portion of the apple-green preci- 

 pitate was calcined, re-dissolved in nitric acid, evaporated slowly 

 to dryness, and again dissolved in water, without leaving any re- 

 sidue ; which would have been the case had any antimony been 

 present. 



The 1-030 parts of arseniate of nickel were decomposed in a 

 silver crucible bv potash ; and yielded nearly equal parts of oxide 

 of nickel and arsenic acid. To separate from the latter the 

 minute quantity of oxide of cobalt, it was dissolved in muriatic 

 acid, precipitated by carbonate of soda, changed to an oxalate 

 by digestion with oxalic acid, and then dissolved in ammonia, 

 according to the process described by M. Langier in the 9th 

 volume of A/males de Chimie et de Physique. In this way 

 about 0*002 of oxide of cobalt was detected. 



As the liquid whence the arseniate of nickel had been preci- 

 pitated by the carbonate of soda might retain some arsenic 

 acid, a known weight of peroxide of iron dissolved in muri- 

 atic acid was dropped in, and again precipitated by carbo- 

 nate of soda, and dried. This precipitate weighed 0'054 more 

 than the peroxide of iron first used, which increase was therefore 

 arsenic acid. Lastlv, all the clear solution was supersaturated 

 with nitric acid, and treated with nitrate of harytes, which threw 

 down OH parts of sulphate of harytes, equal to 02 of sul- 

 phur. 



The above analysis therefore yielded the following products: 



Protoxide of nickel 0*512 



Protoxide of cobalt 002 



Arsenic acid 0747 



Sulphuric acid 0*048 



Oxide of antimony 0-110 



1-419 

 with a trace of oxide of iron and manganese. 



But 



