n real Add of ColalU 101 



•acid by means of ammonia, and to ascertain whether it 

 contained, besides nitrate of ammonia, cobaltic acid. For 

 this purpose the following experiment was made : 

 IBxperbnent VII. 

 The above fluid, which contained the nitrate of ammonia, 

 formed in the preceding experiment by decomposing the 

 nitrate of cobalt by annnonia, being evaporated to dryness, 

 •the result was a brownish black residuum, which exhibited 

 exactly the same phaenomena as nitrate of ammonia. When 

 <lissolved in distilled water the solution gradually acquired 

 a reddish colour, and the blackish residuum of oxide of 

 .cobalt which remained on the filter did not weigh com- 

 pletely two grains. The liquor exhibited the fbllowmg 

 phaenomena: 



It gave scarcely any red colour to litmus paper; it did 

 not produce the least turbid appearance in a solution of sul- 

 phate of copper : the case was nearly the same with an am- 

 moniacal solution of copper : riitrate of silver l>ecame a little 

 turbid, and in a little time the cloudiness assumed a brownish 

 •colour: acetite of lead was rendered a little turbid, but 

 scarcely perceptible, and without xiepositing a precipitate 

 after long rest; in muriate of barytes no turbid appearance 

 was observed : a drop of nitric, acid added to a dram of the 

 turbid fluid occasioned no complti:e solution. 



The phsenoniena of this experiment prove in the clearest 

 manner, that a trace of arsenical acid, but no real cobaltic 

 acid, was present. This result, and no other, can be de- 

 duced from the above experiments ; and it seems to be 

 placed bc)'ond all doubt, that cobalt cannot be converted 

 into an acid, at least by treating it with nitric acid. 



After these ineffectual attempts to produce cobaiUe acid, 

 by treating cobalt with nitric acid, I determined to try 

 Scheele's process for forming arsenical acid; and though I 

 entertained some doubts of obtaining cobaltic acid by this 

 process, in consequence of having considered the circuiia- 

 stances more maturely, and of knowing that the muriatic 

 acid has more affinity for oxygen than cobalt, as the muri- 

 atic acid, when it comes into^perfect coiitact with oxide of 

 cobalt, takes from it a part of its oxygen, and is converted 

 into oxvgenated muriatic acid, I was dcsirou:, of not k-aving 

 it untried, and therefore proceeded in the following manner j 

 Experiment VIII. *. 



A hundred grains of carbonated oxide of cobalt, obtained 

 and collected in the preceding experiments, anduhichcou- 

 -equcntly were free from arsenic acid, were healed with three 

 G 3 drams 



