1822.] Method of aiialyzing the Ores of KickeL 20^ 



This ore of nickel excited my curiosity some time since, when 

 I examined several minerals in order to discover selenium in; 

 tliem. The sulphur which it contains proved to me that it 

 differs entirely from arsenical nickel, and 1 intended to analyze. i 

 it upon a future occasion. In the mean time, M. Psaff pubhshed 

 an analysis of it, which might render any further examination 

 superfluous, if there had not been so considerable a loss. Some 

 phenomena which I observed at the time of my first experiments 

 induced me to undertake this analysis ; and the difficulty of 

 obtaining a satisfactory result engaged me in numerous 

 researches. 



II. Examination of some Substances which are obtained in the 

 Analyses of the Ores of Nickel. 



Arseniate of Iron. — The red oxide of iron combined with the 

 arsenious and arsenic acids is soluble in caustic ammonia, and 

 gives a red coloured solution. If the solution also contains 

 sulphuric and nitric acids, it deposits in a few days a yellow 

 powder, which dissolves in water, in attempting to wash it upon 

 a filter. If a solution of arseniate of peroxide of iron in nitric 

 acid be evaporated until the greater part of the acid is volati- 

 lized, a white powder is obtained, that is insoluble in water, and 

 which is neutral arseniate of peroxide of iron. When subjected 

 to a scarcely visible heat, it loses 17*68 per cent, of v/ater, and 

 becomes red ; but if the fire be increased to redness, it appears 

 to ignite for a moment, and becomes yellowish-white. The 

 water contains twice as much oxygen as the base. If caustic 

 ammonia be poured upon this arseniate before it is dried, it is 

 readily dissolved ; the dry arseniate requires some digestion to- 

 dissolve it. The red solution left exposed, evaporates, and loses 

 its excess of ammonia, but does not deposit any thing, and 

 finishes by forming a transparent red mass. This mass is a 

 double subarseniate of peroxide of iron and ammonia. When 

 heated in a proper apparatus, it gives at first much ammonia and 

 a little water ; but at the moment in which the mass begins to 

 redden, water, azotic gas, and arsenious acid, are disengaged, 

 and the latter sublimes. The residuum acquires a greenish 

 colour, and appears to be an arsenias-ferroso^ferricus. The 

 double subsalt in question dissolves in water mixed with a little 

 ammonia, but pure water decomposes it, and dissolves arseniate 

 of ammonia, as well as a small quantity of undecomposed double 

 subarseniate, the residue left being a subarseniate of peroxide 

 of iron. 



The subarseniate of iron is not soluble in ammonia, even 

 though it be first dissolved by an acid, and ammonia added to 

 the solution. Consequently when in a solution which contains 

 peroxide of iron and arsenic acid, the latter is sufficient only to 

 form a subarseniate of the peroxide, the addition of ammonia 



^ew Series, vol. iii. p 



