C—3.

No. 6. — Broken Hill Mine, Waiomo. This ore consisted of a parcel of moderately-hard yellowish-brown quartz, containing a small percentage of iron-pyrites and a little copper-pyrites. The whole of the ore was dried and drycrushed. The first 2,0001b. showed the following value by fire-assay : — Oz. dwt. gr. Bullion ... ... ... ... ... ... 11 19 5 per ton. Gold , ... ... 0 12 14 Silver ... ... ... ... ... ... 11 6 15 Value, £3 12s. per ton. This portion was subjected to a leaching by percolation with a 0-45-per-cent. solution of potas-sium-cyanide, which extracted 4oz. of bullion, valued at 11s. 6d. per ounce, representing a saving of 93 per cent, of the gold, 21 per cent, of the silver, and 76 per cent, of the original value. The remaining 1,3001b. of ore showed a value of— Oz. dwt. gr. Bullion ... ... ... ... ... ... 12 18 16 per ton Gold ... ... ... ... ... ... 1 9 8 Silver ... ... ... ... ... ... 11 9 8 Value, £7 os. 4d. per ton. and was treated in a pan by raw hot amalgamation with chemicals, and yielded 4oz. lOdwt. of bullion, valued at 10s. 6d. per ounce, representing a saving of 60 per cent, of the gold, 56-3 per cent, of the silver, and 59-3 per cent, of the value. The average value of the whole parcel was thus— Oz. dwt. gr. Bullion ... ... ... ... ... ... 12 8 22 per ton. Goid ... ... ... ... ... ... 1 1 0 Silver ... 11 7 22 Value, £5 6s. 2d. per ton. The comparative results of the recovery by the different processes were as follows : — By Washoe Process. By Cyanide. Gold ... ... ... ... 60 per cent. ... 93 per cent. Silver ... ... ... ... 56-3 „ ... 21 Value ... ... ... ... 59-3 „ ... 76 These results prove conclusively the superiority of the cyanide process for the treatment of this ore. The recovery of 76 per cent, of the value is a very satisfactory result considering the smallness of the parcel operated upon and the large proportion of silver in the bullion. The very small amount of copper in the ore was not found to cause an excessive consumption of potassium-cyanide, and, although it showed on the zinc in the extractor, it did not hinder the precipitation of the gold and silver. No. 7. — Fisher Brothers, Punga Flat, Thames. This was a parcel of rusty-coloured mullocky quartz. It was dried, dry-crushed, and found to weigh 1,9001b. After sampling, it was assayed, with the following results : — Oz. dwt. gr. Bullion ... ... ... ... ... ... 13 16 7 per ton. Gold ... ... ... ... ... ... 8 0 4,, Silver ... ... ... ... ... ... 5 16 3 Value, £32 12s. per ton. It was then subjected to hot pan-amalgamation, which saved 10oz. of melted gold, 0-6378 fine in gold, and 0-3610 fine in silver, equal to a value of 575. 9d. per ounce, and representing a saving of 93 per cent, of the gold, and 90 per cent, of the silver, and 90*5 per cent, of the original value. A considerable proportion of the gold existed in a coarse form, which would render the treatment of this ore by the cyanide process both tedious and expensive. The above results are most satisfactory, and show that a very high percentage of the precious metal can be extracted as one operation by pan-amalgamation in charges after the ore has been reduced to a pulp by dry-crushing. No. B. — Grace Darling, Waitekauri. This consisted of half a ton of pulverised ore. It contained a considerable proportion of manganese-oxides. It showed the following assay-value :— Oz. dwt. gr. Bullion ... ... ... .. .. ... 3 17 22 per ton. Gold ... 0 6 7 Silver 3 11 15 Value, £1 10s. 6d. per ton. The dry pulp was subjected to raw hot pan-amalgamation-, and yielded Bdwt. of bullion, 03361 fine in gold, and 0-6497 in silver, valued at 28s. per ounce, representing the following percentage of extraction : —■

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