Macfarlane on the Acton Copper Mine, 465 



occur in ore veins, the importance of the agency of tlie alkaline 

 sulphurets in the filling up of such can scarcely be over-rated.* 



This sketch of the recent results of mining at Acton, would 

 scarcely be complete without a description of the processes em- 

 ployed for concentrating the ore, and a reference to certain experi- 

 ments instituted for the purpose of ascertaining the amount of 

 copper lost in the processes of crushing and jigging. 



As soon as the ore has been brought to the surface it undergoes 

 the process of coarse spalling ; that is, it is separated from the 

 waste rock, and broken into pieces having a diameter of from four 

 to six inches. These pieces are sorted, according to the quantity 

 of copper they contain, into first quality ore, second quality ore, 

 crush ore and fourths. The first three sorts then undergo the pro- 

 cess of fine spalling. The first quality ore is broken into pieces 

 of the size of an egg^ and any poor rock which these may con- 

 tain is picked out. It thus yields marketable first quality ore, 

 containing from eighteen to twenty-four per cent. The second 

 quality pieces, treated in the same way, yield marketable second 

 quality ore, containing from ten to thirteen per cent. The 



Editofs note, by T. Sterrt Hunt, f, r. s. 



De Senarmont, in his researches on the artificial formation of the min- 

 erals of metalliferous veins by the moist way, has shown that by the aid 

 of heated solutions of alkaline sulphurets and bicarbonates, at tempera- 

 tures of 200O and 300^ Centigrade, it is possible to obtain in a crys- 

 talline form many of the native metals metallic sulphurets, and 

 sulpharseniates, besides quartz, fluor spar and sulphate of barytes. These 

 observations, and those of Daubree are cited by me in a paper in the 

 Naturalist for December 1859, p. 500, with the remark that, in them, " we 

 have, beyond a doubt, a key to the true theory of metalliferous veins.' ' 

 Heated alkaline solutions (sulphurets and carbonates,) which are at the 

 same time the agents of metamorphism, dissolve from the sediments the 

 metallic elements which these contain disseminated, and subsequently 

 deposit them, with quartz and the various spars, in the fissures of the 

 rock." Mr. Macfarlane's view seems to be in perfect accordance with 

 the theory which I have advanced. The notion that the contents of the 

 rein have been deposited from springs coming from below, is in no 

 way inconsistent with that of their secretion from the wall-rock, inas- 

 much as we conceive that metalliferous and other mineral waters, in all 

 cases, derive their soluble matters from certain permeable strata, and 

 may afterwards either deposit these dissolved matters in the same strata, 

 or more frequently rise to higher formations, where a lower temperature if 

 more favorable to the precipitation of the dissolved elements. 

 Oah. Nat. 30 Vol. VII. 



