302 Dr Turner's Analysis of Kuchruite. 



it fuses completely, and crystallizes on cooling into a green- 

 ish brown mass. Heated before the blow-pipe on charcoal, 

 it fuses readily, and at the same moment deflagrates ; the 

 odour of arsenic is then also perceptible, and white vapours 

 rise. On continuing the blast, a distinct copper corn is left. 

 If the reduction is performed in a glass tube, both a metallic 

 crust of arsenic and minute crystals of arsenious acid con- 

 dense on the cold parts of the glass, which are easily and com- 

 pletely driven off by heat. 



It dissolves readily in concentrated and diluted nitric acid 

 without effervescence, or formation of nitrous acid fumes, even 

 on the application of heat. The addition of water neither 

 caused precipitation, nor disturbed the transparency of the so- 

 lution. Ammonia occasioned a greenish blue precipitate, 

 which was wholly redissolved by an excess of the alkali, form- 

 ing the blue solution characteristic of the peroxide of copper. 

 The nitrate of silver caused no precipitate, nor did the mu- 

 riatic and sulphuric acids. The absence of iron was proved 

 by the tests of ammonia, ferrocyanate of potash, infusion of 

 galls, and sulpho-cyanic acid. Acetate of lead caused a white 

 precipitate, soluble in an excess of nitric acid. A stream of 

 sulphuretted hydrogen, the sulphuret of copper which first 

 fell being separated, gave rise to the formation of orpiment. 



It appears from these observations, that Euchroite contains 

 nothing but arseniate of copper, and water of crystallization. 

 To determine the amount of the latter, 3.905 grains were heated 

 at the flame of a spirit-lamp, in a clean glass tube, till all the 

 water was expelled. The loss amounted to 0.73 grains, or 

 18.69 per cent. In another experiment, 2.565 grains lost 

 0.485 of a grain or 18.9 per cent. Taking the mean of these 

 experiments, Euchroite contains 18.8 per cent, of water of 

 crystallization. The water, as it condensed in the cold parts 

 of the tube, was carefully tested by delicate litmus-paper, 

 which was not reddened in the least ; and I am satisfied, that 

 all the water can be separated, by heating cautiously, without 

 the loss of any acid. 



8.35 grains of the anhydrous mineral were dissolved in 

 dilute nitric acid, and then a concentrated solution of pure 



