^48 M. Berzellus on the [June, 



from combining with a fresh quantity of chlorine gas. It is, 

 therefore, necessary to peroxidize the iron, by adding nitric 

 acid, and heating it to ebulHtion. Afterwards it is saturated 

 with ammonia, and the iron precipitated with succinate of am- 

 monia ; and at last, excess of ammonia is added, to be certain 

 that no substance insoUible in ammonia should remain in the 

 liquid. 



The amnionical solution is to be much diluted with water, 

 deprived as much as possible of atmospheric air, and the oxide 

 of nickel is to be precipitated by caustic potash. The oxides of 

 cobalt and copper remaining in the solution, are deposited 

 during the evaporation of the ammonia. The silica is to 

 be looked for in the alkaline solution, by saturating it with 

 muriatic acid, and evaporating it to dryness ; water then dis- 

 solves the salts, and leaves the silica. Oxide of nickel, as well as 

 'cobalt, frequently contains sihca, which must be separated 

 from it by dissolving the oxide in muriatic acid, and by eva- 

 poration to dryness, which renders the silica insoluble. As to 

 the separation of the metallic oxides with which those of nickel 

 and cobalt may be mixed, I refer to what I have already stated. 



The water in which the acid vapours are condensed, contains 

 arsenic and sulphur ; but if the mineral contains at the same 

 time bismuth, zinc, antimony, or tin, the muriates of these me- 

 tals will also be found in the liquid. This last circumstance 

 would render the analysis extremely complicated, and I, there- 

 fore, do not describe it on the present occasion. 



The bottle, H I, ought also to be furnished with a glass stopper. 

 The interior of the tube, IK, is to be washed, the* bottle is to 

 be stopped, and left in a warm place, in order that the greater 

 part of the sulphur precipitated may be acidified. If any portion 

 of it remain, the bottle is to be unstopped and the liquid 

 boiled ; the sulphur agglutinates, and may be then conveniently 

 washed, dried, and weighed. 



In order to be certain that the acid liquor contains no iron 

 in consequence of any mistake in the operation, nor any me- 

 tals, the muriates of which are volatile, it is to be saturated 

 as perfectly as possible with caustic potash. If any precipitate 

 is formed, it is to be collected and examined. The solution is 

 to be again rendered acid, and the sulphuric acid is to be pre- 

 cipitated by muriate of barytes. It is then proper to separate 

 the excess of muriate of barytes by an addition of sulphuric 

 acid ; but this is not absolutely necessary. Afterwards a known 

 quantity of iron dissolved in nitric acid is to be poured into the 

 remaining liquid, and the oxide of iron and arsenic acid are to 

 be precipitated by ammonia in excess. If the other ingredients 

 have been determined, the quantity of iron required to preci- 

 pitate the arsenic acid, may be estmiated with more precision. 

 For one atom of arsenic, two atoms of iron are to be used, 

 which are to each other in weight, as three parts of iron to two 



