e/" Copper and of Iron, 303 



higheft amount of copper (that given by Fontana) does not 

 exceed 66 per cent., and is far Ihort of the real quantity. 

 The remainder, as he dates, confills of water and of pure 

 and fixed airs. The difference in the refults I Iiad obtained, 

 together with feme new fafts, which I had occafion to ob- 

 ferve during my experiments, induces me to treat the fubje6t 

 at feme length; referring for its external charafters to thofe 

 mineralogies above mentioned, who have amply defcribed 

 the ore, and confining myfelf entirely to its chemical ana* 

 lyfis, and fume analogous experiments. 



One hundred parts of very pure and regularly cryftallized 

 red copper ore were reduced to a fine powder, and dillblved, 

 without the affiftance of heat, in nitric acid. 



During the operation, a very violent eflervefcence, accom-» 

 panietl bv a difengagement of nitrous gas, unufually copious 

 and rapid, took place. When thefc phaenomena had fub- 

 fided, the lolufion was blue, like every other nitrate of cop» 

 per; and the ore had entirely difappeared. The liquor, per- 

 fc(5lly limpid, was evaporated to drynefs ; muriatic acid was 

 poured in, and the nitric acid was expelled by a fecond eva- 

 poration. Into the muriate of copper, which remained be- 

 hind, a plate of polifhed iron was immerfed, which, after 

 the ufual phenomena, gave a precipitate that w^as found, 

 upon examination, to be copper, and amounted to ii^,l^. 

 In order to complete the hundred parts, it would be neeel- 

 fary to add 11,5. But fire expelled from the ore neither 

 water nor any other volatile fublbnce ; nor did the weight 

 of a given quantity appear either to diminifli or to incrcafe 

 by long expofure to a mydera'tely elevated temperature. The 

 only oxide of copper with which I was acquainted, as ejcifi- 

 ing in nature, contains 20 per cent, of oxygen. I had there- 

 fore 8,5 of copper exceeding the quantity I fliould have ob- 

 tained had the ore been wholly compoled of black oxide of 

 copper. And, on the other hand, as 1 had convinced myfelf 

 that no lofs of weight had been occafioned by any part of the 

 metal remaining unprecipitalcd by the iron from its fohilion, 

 I could not conclude the ore to be in the Hate of native cop- 

 per. I was led, therefore, to imagine, that it might be a 

 mixture of thofe two (uljftances ; and that muriatic acid, by 

 diflblving the one, and leaving the oiher untouched, would 

 be the mofl eilc'^lual means of producinij the fcparation I 

 defired, and of determining the proportion of each. 



Upon 100 )jarts of the ore a fuflicicnt quantity of (Irong 

 muriatic acid was poured. A total iuhstion was elfcil^tcd, ac- 

 conipinied with difcnfragement of caloric. 'Ihe liquor was* 

 at iird, of a very deep brown, ajjproacliing (onitvvhut to tb« 



6 tingt 



