276 Klaproth on the Chemical Analysis 



1000.00 

 To the above analysis Klaproth adds some remarks respect- 

 ing the state of the mercury in the red sulphuret. 



Chemical Examination of the Lamellar Red Copper Ore of 

 Siberia. 



a. 100 grains of selected crystals of the above ore were 

 digested in cold muriatic acid : the mixture became warm 

 without effervescing ; the ore lost its red colour, becoming 

 greyish white, and the acid acquired a dark brown colour. A 

 fresh portion of acid was added, by which the grey portion of 

 ore was taken up, and some particles of metallic copper re- 

 mained undissolved, which however ultimately disappeared on 

 continuing the digestion. 



b. On pouring the solution into water, it became decomposed, 

 and deposited a white precipitate of sub-protomuriate of copper, 

 which, upon adding excess of potassa, acquired an orange 

 colour; the whole was then poured upon a filter, and the re- 

 sidue being washed and dried, proved to be protoxide of copper, 

 of a rhubarb-yellow colour. 



B. From these experiments it appears that the copper in 

 the above ore is in the state of protoxide. To ascertain the 

 relative quantity of oxygen to that of metal, 100 grains of the 

 ore were carefully digested in a stopped phial with muriatic 

 acid, so as to leave the metallic copper undissolved, which was 

 collected in small crystallized particles, and weighed 12 grains. 

 The solution, containing 78 grains of pure red copper ore, was 

 heated to its boiling point, and nitric acid added drop by drop, 

 till it became of a grass-green colour ; it was then diluted, and 

 after a small addition of muriatic acid, was heated and decom- 

 posed by zinc, by which the copper was separated, and after 

 being washed and quirkly dried, was found to weigh 71 grains 



