LEYS INSTITUTE.

Auckland Star, Volume XXXVIII, Issue 136, 8 June 1907, Page 6

LEYS INSTITUTE.

TEE WINNING OF GOLD. Professor A. Jarman, A.R.S.M.. London, A.1.M., London, and M.A.1.M.E., delivered an instructive and also interesting lecture last evening at the Leys Institute, upon " Gold, and the winning of it from Mother Earth."' The attendance was large, and the keenest interest was manifested by all present. Mr. C. W. Leys (President of the Institute) in introducing the speaker, said Professor Jarman was a comparative stranger, having arrived here withiu the last two years to take charce of the School of Mines at the Auckland University College. Mr. Ley? said he did not wish lo speak disrespectfully of anything ancient, but. there was a 'decrepitlooking place just behind the. rather English-looking Supreme Court buildings. Thai was the Auckland University College building: but although the mining school had been started, _nfortuuately there were no prope-r facilities there for Professor Jarman'to carry on his valuable work. Science had done a great deal for mining, and when they had proper buildings and greater facilities, Professor Jarman would have better opportunities for giving instruct ion in mining, which was a inosr important matter in the Auckland district. Professor Jarman was received with applause. He said that after being here lourteen months, the University College in Auckland was still without suitable buildings, or even a proper site. They hoped to have proper facilities some time, in the future, and they could ! not possibly look for satisfactory results until those hopes were fulfilled. Professor Jarman first referred to gold as one of the noble metals, in which class was also silver and the platinum group. Gold was so extremely malleable that one grain could be drawn into something like 500 ft., and if it were possible to do so. an ounce troy weight would make a wire 4->_ miles in length. Gold could lie very easily redue-ed from compounds, heme it. was generally found in the metallic state. The exceedingly high density of gold assisted in its separation from other metals. Gold also amalgamated very readily with mercury, which euableel its separation quickly from pulverised ore. It was also easily saved by- a very weak solution of cyanide of pota-ssiuin. Geild was also readily dissolvi-d by molten lead or copper, hence the system of smelting sulphide ores, which was a very easy method of separating gold. Professor Jarman then described hydraulic sluicing, also the system of dry blowing to save gold, as practised at Kalgoorlie, Coolgardie. and elsewhere. This was illustrated by "-leaps of a miner's dish. Where waft* Was obtainable, he said, the same result, was obtained by dish washing. He then described the system of say ing gold in a miner's cradle, also a Long Tom. The j occurrence of gold was next referred I to as being the result of the deposition of matter by water in which gold" was ] (in solution) in large earth cracks. He j pointed out that at a great depth in tin? i earth, the temperature of water ap- I proaehed boiling heat, and this, coupled j with the immense pressure, most probably made the gold more readily absorbed by the water. As the water ! flowed alons; the earth cracks, and the , temperature deeieasea, the gold would I be deposited. He next described the de- I position of alluvial gold, as the result I of the eroding of the rocks, by water, or by glacier action. Having briefly de- I scribed gold and its occurrence, Profess | sor Jarman next, by means of lantern ! views, showed the various methods of j winning Ihe gold, by means of dry blowing, sluicing, elredgiug, quarrying, and reef fining. Iv one view the steam shovel was shown in operation. A number of interesting pictures were also shown of various mines and mining plants. Miners were shown breaking out j the. quartz, also working tbe hand drill, j and in another view the drill driven by j compressed a "it was shown. The final | portion of the lecture was the method | of saving gold. The pictures included a ; Huntingdon rotary mill, the Waihi Grand Junction forty-stamper battery, I aud the tube mills were shown and described, also the Wifiey tables for say- \ -ing concentrates. Finally the cyanide I plant was shown and the whole system . of gold saving described down to the I process of .ptorting. Professor Jarman I said to go into the question of pyritic , smelting would take too long. In deal- | ing with sulphide ores they had a smelt- j ing proposition which had proved so, successful when dealing with the leadzinc ores at Broken Hill. Professor | Jarman had with him a number of j specimens of various types of ore which i were examined with interest at the j close of the lecture. j On the. motion of the chairman a | j hearty vote of thanks was accorded the j lecturer. |