NICKEL AND COBALT. 265 



fiilphuric acid which he ufed, altogether throw doubts on the 

 cxaftnefs of the procefs indicated, which the following expe- 

 riments may elucidate. 



1. A portion of the carbonic oxide of nickel, A 4, was Experhnents on 

 expoled daring an hour in a ftrong fire to a red heat approach- pro^fj^'^*" '" 

 ing while heat. The oxide while hot was of a brownifli 



yellow; after cooling it alTumed a grey colour inclining to 



yellow, but not yellow. The oxide obtained by the evapo- _,. 



ration A 4, having been treated in the fame manner was dill ;ii: 



a little more grey than the preceding. The carbonic oxide of 



nickel was placed again for half an hour in a white heat ; 



while hot it was yellow inclining to brown, but when cool, it 



was grey inrclining to browni(h yellow. 



2. Thirty grains of this oxide made red (hot), were put 

 for fome hours to digeft, with ninety grains of pure fulphuric 

 acid of the fpecific gravity 1,360. Being then heated, the 

 mafs immediately fwelled up with an explofive noife, and ex- 

 hibited a yellow fubftance inclining to a green ; by means of 

 ebullition with half an ounce of water it was diflblved, ex- 

 cept about a grain of a yellowiQi-grey powder, which proved 

 to be an oxide of nickel mixed with cobalt and a little dirt. 

 Thirty-five , grains of oxide of nickel, (obtained by heating 

 brilkly to rednefs 60 grain* of ammonical nitrate of nickel 

 prepared by evapora(ion), afforded the fame refult, and the 

 fame phenomena, on being treated in the fame manner : The 

 fame oxide being healed for half an hour to whitenefs, ufing 

 the bellows at the fame time, did not afford a yellow mafs, 

 but one of a yellowifli grey inclining to a green, which had 

 the fame e/fed with fulphuric acid that has been already re- 

 fated. 



3. The experiment was again repeated with diluted ful- The experimf«t 

 phuric acid ; 160 grains of ammonical oxide of nickel, which dXTeffJph^. 

 had been precipitated from many folulions were expofed for nc acid. 



half an hour to the moft violent white heat, under the ope- 

 ration of the bellows, after which they weighed 75 grains. 

 This fubftance was of a greenilli yellow here and there, and 

 of a blueifh grey where it touched the crucible ; being broken 

 it produced a black grey powder. It was mixed with a dram 

 of fulphuric acid dilated with five drams of water? at that 

 inftant there was a rapid difengagement of gas, find on beating 

 thsmixture it evidently gave out hydrogen gas. After a fuffi- 



cient 



