^©4 Analyjis of the Arjeniates 



tins;e which water will receive when ftrongly impregnated 

 wiTh the colouring matter of dried vegetable fiibftances; but, 

 upon being expofed to the air, and boiled ibme time, it be- 

 came like every other muriate of" copper; and a plate of po- 

 lHhed iron precipitated 88 of metallic copper. From this laft 

 experiment it was evident that no metallic copper was con- 

 tained in the ore. But ftill the deficit to be fupplied by oxy- 

 gen amounted to no more than ici; while the copious dif- 

 eno-agement of nitrous gas, in the firll experiment, indicated 

 that the metal was not at its maximum of oxidation ; and the 

 rapidity with which it fcizcd upon an addition of oxygen, 

 fufficiently (howcd how flrong was the affinity of that prin- 

 ciple for copper, in that particular ftate in which it exifts in 

 the ore. 



I imafrined it would be expedient to attempt fome precipi- 

 tations by other reagents, and make fome further experi- 

 ments. For this purpofe, I diflolved fome more of the ore 

 inftrong muriatic acid ; and, when I thought that the acid 

 had taken up as much as it could contain, and that the co- 

 lour had arrived at its deepcll tinge, I gently drew off the 

 clear liquor, ufing all the precaution which the nature of the 

 experiment allowed, to preferve it from the contact of the 

 atmofphere, and proceeded to examine it. Knowing this 

 folution of muriate of copper to be very concentrate, I at- 

 tempted to dilute it ; but what was mv furprife, when, upon 

 the firft affufion of water, I faw the liquor become turbid 

 and milky, and a very abundant heavy precipitate, of a white 

 colour, full to the bottom ! 



Struck with the novelty of this appearance, I proceeded to 

 coUeft as nuich of the fubftance as I could, in order to give 

 it a thorough examination. For this purpofe, I decanted the 

 fnpernatant liquor, and continued to walh the precipitate. 

 Upon every fublequent addition of water, I perceived that 

 the precipitate loll a little of its whitenefs, and drew towards 

 an orange colour, not unlike the precipitates of platina. I 

 foon found, therefore, that by this method I had no chance 

 of obtaining, in a permanent and conilant ftate, this muriate 

 of copper, fit to be fubjetlcd to experiments proper to deter- 

 mine its interna! nature and proportions. I then attempted 

 to make ufe of alcohol, as precipitant, inftcad of water; but 

 I found the fait to be foluble in it, when the excefs of acid 

 neceflary for its folution in water was prefcnt. Nor was I 

 more fuccefsful, when, after having precipitated by water, I 

 waflied with alcohol ; for the colour of the fait pafled gra- 

 dually from very white to a (hade of orange; lefs rapidly, it 

 is true, in this cafe, but Hill fo as to convince me that I 



could 



