08 Ijxpcnwentsfor nsccrtaifiiri^ the K.risfencf of 



tlon of tlie cobaltic acid from cobalt and the oxygen of ni- 

 trous- acid, is favourable to the assertion of JBrugnatelli ; but 

 it is impossible to consider such experiments, results,, and 

 deductions, so satisfactory and convincing as to render this 

 subject unworthy of further rescaa-ch. For mv part, I am 

 of opinion that thev are not convincins or satisfactory j 

 especially as it is not proved in general that arsenic can be 

 complctelv separated from cobalt, according to the method 

 of Lampadius, by a current of air, or by Fiedler's applica- 

 tion of this process. 



Experiment I, 



Fom* ounces of nitric acid of the specific gravity of 

 }"2B0 were poured over two drams of carbonated oxide of 

 cobalt as pure as possible, ecjual to one dram of pure oxide- 

 of cobalt, and distilled to dryness in a retort. No traces of 

 nitrous gas or nitrous arid appeared, from which it could 

 be concluded that an oxidation of the cobalt or a dcoxida- 

 tion of the nitric acid had talcen place. The nitric acid 

 which passed over without any changx', was again poured 

 into the retort over the cobalt, and distilled to dryness in a 

 gentle heat, but with the same result. And the same was 

 the case when the process had been repeated four times. 

 'I"he nitric acid remained nndecomposed, and the residuun^ 

 was nitrate of cobalt, from which the oxide of cobalt could 

 be separated as a blue precipitate, both by potash and by 

 ammonia. 



Experiment II. 



But as It was possible that the precipitate, which had a 

 perfect resemblance to one obtained from a solution of co- 

 balt in muriatic acid, mi2;ht contain the cobaltic acid, I di- 

 gested it with pure ammonia : a little cobalt was dissolved, 

 out no traces of acid were found in the solution evaporated 

 to drpie^s. 



JEorperimcnt III. 



I now evaporated to dryness the fluid from which I had* 

 separated the oxide of cobalt by means of anjmonia, and 

 which, besides nitrate of ammonia, still contained some 

 tedissolved oxide of cobalt. The saline mass thus obtained 

 was of a reddish appearance, and had the taste of an ammo- 

 niacal salt with a little metallic astringcncy. The half of this 

 ilaline mass being then decomposed Dy heat in a porcelain 

 dish, the result was a black oxide of cobalt. The other half, 

 being dissolved in water, exhibited no other phcenomenj^ 

 with the usual reagents than those which gave reason to 

 Suspect some tracer of arseni.cal acid. Though the result 



