COPPER 



937 



The quantities of ore raised and copper obtained are given as follow in tho 'Mineral 

 Statistics ' for the last few years : 



Mono, and Pary's Mines, Anglesea. The waters draining from the enormous heaps 

 accumulated from the old and remarkable workings of these mines are collected in 

 large ponds and precipitated by iron. In 1872, the Mona Mine produced 2,400 tons of 

 copper ore, but there was no precipitate ; but Pary's Mine produced 155 tons of preci- 

 pitate and 2,813 tons of copper ore. 



Wicklow Mines. Similar precipitating processes were carried on in these mines. 

 The process is thus described by Mr. W. W. Smyth, in his ' Mines of Wicklow and 

 Wexford': 



From a letter of the Rev. William Henry, D.D., inserted in the ' Philosophical 

 Transactions ' for 1752, we learn that the existence of copper in solution in the water 

 flowing from Ballymurtagh has only lately been discovered by accident, but had 

 given rise to extensive apparatus where 500 tons of iron were at the same time 

 employed to effect the precipitation of the costlier metal. The mode of operating was 

 very rude ; pits were dug, 10 feet long, 4 feet wide, and 8 feet deep, floored with flags 

 and lined with stone, and the iron bars were laid on rough wooden beams fixed across 

 from wall to wall. Dr. Henry's statement of the everlasting efficiency of the water, 

 shows that, by him at least, the rationale of its action was little understood. ' Chains 

 of these pits are continued along the stream, as far as the directors please, for the 

 water never abates of its quality, if it were conveyed from pit to pit through a 

 thousand.' 



By this mode a ton of the precipitant obtained from the pits yielded 16 cwts. of the 

 finest copper. Dr. Rutty states, that in seven years previous to 1765 the Cronebane 

 water had yielded 17,260/., from precipitate-copper; the precipitate affording above 

 half of pure metal. 



Towards the close of last century, copper was obtained by the same means at 

 Cronebane and Tigroney. According to the ' Journal des Mines,' vol. iii., it was 

 usual to add to the strength of the solution, by placing in the water a quantity of 

 poor pyritous ore which has undergone a process of roasting. The form of the pits is 

 not described, but the ratio of pure copper to the precipitated powder was only 0'328. 



The quantity of precipitate or cementation-copper exported to England was, in 1788, 

 Hi tons; in 1789, 37 tons; in 1790, 59f tons. 



During Mr. Weaver's management, the water was run into tanks in which the 

 muddy particles were allowed to subside, and then passed into pits filled with plate and 

 scrap iron ; the quantity precipitated during that series of years was 442 J tons, which 

 sold on an average at 271. 8s. Qd. per ton, being in aggregate value 12,126^. ; whilst 

 the consumption of iron was rather less than one ton to the ton of the precipitate. 



At the present date the water is economised at all the Ovoca Mines, but by a some- 

 what different method it is led through a series of narrow troughs or launders, inclined 

 at angles of 10 or 12, and interrupted at intervals by a deep chest or 'hutch.' At 

 Tigroney the precipitate is swept down with brooms every night and morning into the 

 hutches, the contents of which are afterwards mixed, and realise 50 to 60 per cent, of 

 copper. The expenses of obtaining it are about 31. per ton for attendance, sifting, &c. 

 At Connarie people are kept sweeping down the launders throughout the day, by which 

 means the precipitate, although more rapidly collected, is more impure, yielding but 

 43 to 54 per cant, of copper. 



M. Bischoffjunr. has patented a process for obtaining copper by precipitation which 

 certainly effects the separation of the copper with great readiness, and, as he assures 

 us, with great economy. His process differs from any other in the circumstance of 

 his obtaining the iron in a peculiar condition. He takes tho ordinary iron pyrites 

 (Mundic), and reduces this to a state of coar&e powder. This is then mixed with coke 

 and exposed to heat in close furnaces. The sulphur is volatilised, and the incan- 



