I860.] Alining. Mineralogy, and Metallurgy. 113 



for copper ore, and are now found to be very auriferous ; but as yet 

 only a very small piece of one of the lodes, the St. David's, has been 

 wrought expressly for gold. This piece has been cut off by a cross- 

 course on the west, and is about 45 fathoms long, chiefly composed of 

 quartz, largely impregnated with gold ; the average yield of gold- 

 bearing quartz is 10 tons per square fathom of the lode. The total 

 amount of the lode extracted, including drivages, sinks, &c, is about 

 350 square fathoms, yielding 3,500 tons of mineral, good, bad, and 

 indifferent, and of which between Jan. 12, 1861, and Sept. 3, 1864, the 

 following quantities were crushed — 



Tons. Oz. dwts. grs. 



Rich picked ore, with visible gold . 39 9 yielding in gold 9,363 15 14 

 Poor ore, without visible gold . . 2,271 8 „ 1,547 1 



Total . . 



. 2,310 



17 











rage yield of all the ore < 

 ,, „ the rich 

 „ „ the poor 



crushed . 

 ore . 

 ore . 





Oz. 



4 



240 







dwts. 



10 

 

 13 



grs. 

 per 

 

 15 



ton, 



" An experiment upon 1,036 tons of the poorest refuse from the 

 lode, yielded \ oz. of gold per ton. Before St. David's lode was 

 found to be auriferous, a large quantity of mineral, rich in gold, was 

 extracted from it, and dressed for copper ore, and the gold was lost ; 

 but whatever the amount, it is included in the 3,500 tons extracted 

 above mentioned. 



" Worked upon a scale of (say) 50 tons per day, a yield of ^ oz. of 

 gold per ton will pay all costs; consequently, the lowest produce, 

 i oz. per tun, would leave half profit. 



" At the Welsh Gold Company's Mines, near Tyn-y-Groes, an 

 experiment upon one of the lodes has just been completed. A mass 

 of 333^ tons has been broken out and stamped, yielding 282£ oz. of 

 gold, or an average of 17 dwts. per ton as broken. The supply of 

 mineral at this mine is, probably, greater than at any other gold mine 

 in Wales, and preparations are now making to erect machinery, a 

 large part of which is at the mines, to stamp 150 tons per day, the 

 average yield being estimated at 10 dwts. per ton." 



In connection with the subject of Gold Mining in Wales, it is right 

 to record Dr. Crace Calvert's method of extracting gold from auri- 

 ferous quartz, or from its combination with silver and copper. Finely- 

 divided auriferous quartz should be intimately mixed with about one 

 per cent, of peroxide of manganese, and common salt added at the 

 same time as the manganese, in the proportion of three parts of the 

 former to two of the latter. This mixture should be introduced into 

 closed vats, having false bottoms with holes in them, upon which is 

 laid a quantity of small branches covered with straw to prevent the 

 powdered quartz from filling the holes. Diluted sulphuric acid is 

 now added, in sufficient quantity to moisten the mass, and the whole 

 allowed to remain in contact for twelve hours. Water should now 

 be added so as to fill up the whole space between the false and true 

 bottoms. This fluid should then bo pumped up, and allowed to pcr- 

 vol. n. I 



