C—3.

5. Give the dimensions and action of a Wilfley concentrator, its capacity in relation to a stamp-mill, and the horse-power required to work it. Subject C.— The Use of Quicksilver, and Methods of using it in connection with the Extraction of Gold and Silver from Ores. 1. How is it ascertained when quicksilver is in a pure state? 2. How are impurities such as antimony, lead, or zinc removed from quicksilver? What effect has impure quicksilver on the amalgamation of gold and silver ? 3. How are copper plates cleaned, and coated with quicksilver ? What steps are taken to keep the plates always bright ? 4. How are gold and silver removed from the copper plates, and also from amalgamatingmachines ? 5. If quicksilver containing antimony or lead were subjected to a current of electricity, how would you apply the electric current, and what effect would it produce ? State fully. Subject D.— Cyanide, Chlorination, and other Chemical Processes of recovering Gold and Silver from Ores. 1. At what plant were you employed where cyanide of potassium was used ? Give the dates of your employment, and the name of the battery-superintendent you were under. 2. How is KCN used in the extraction of gold from pulverised material, and how is its purity ascertained ? 3. Describe fully how stock solutions of KCN are made up. 4. In using a 15-per-cent. solution of KCN to make up 40 tons of a sump solution containing 0-09 per cent, of KCN to a 3-per-cent. solution, how many pounds of the 15-per-cent. solution would have to be used ? 5. To make up 60 tons of a sump Solution containing o'o3 per cent. KCN to a solution of 0-25 per cent. KCN, how many pounds of crude cyanide of 65 per cent. KCN would be required ? 6. How many pounds of crude cyanide of 72 per cent. KCN would be required to make up 47 tons of water to a solution containing o'2B per cent. KCN ? 7. What effect has concentrated iron or copper pyrites on a solution containing KCN used in dissolving the gold contents ? 8. A vat 40 ft. in diameter is filled with pulverised ore to a depth of 5 ft. or more : how many tons of KCN solution is required to treat this vat ? 9. In treating tailings containing a very small percentage of gold, is there any limit to the weakness of the solution used when zinc is the precipitant ? And why ? What substitute for zinc can be used as a precipitant in weak solutions ? 10. Show by sketch, and describe, how you would treat slimes by using compressed air for agitation in a KCN solution. State the time used in agitation, or how you ascertain when the slimes are sufficiently agitated. Also state how the solution is extracted from the gangue. 11. What are the antidotes to KCN poisoning, and how are they applied? What steps would you take at once if you found a workman suffering from KCN poisoning ? 12. Describe how the ore is prepared for chlorination, and how it is treated by the Piattner process, and also by the Newbery-Vautin process. Describe fully. 13. How is the gold recovered from chlorination, also from KCN solution? Describe fully the different treatment it undergoes before it is in a marketable state. Subject E.— Sampling and Testing of Ores. 1. How would you take a sample for assay from ten truck-loads of quartz as it comes from the mine ? 2. Describe the fire assay of a sample of quartz for gold and silver. What modifications of the process would you employ if the sample consisted largely of (a) iron-pyrites, (b) galena, (c) iron-oxide ? 3. How would you determine the percentage of tungsten in a sample of scheelite ? 4. What tests would you make in order to detect, the following elements when occurring singly in rocks : Chromium, bismuth, tin, mercury, arsenic, cadmium ? 5. How would you prove the presence of the following in a sulphide ore : Iron, lead, arsenic, silver, cobalt ? Subject F.— A Knowledge of Arithmetic and the Method of keeping Battery Accounts. 1. A Pelton water-wheel is required to give 120 effective horse-power, the Pelton giving 80 per cent, of the power of the water. Eequired the number of cubic feet of water per minute, with a head of 200 ft., to produce the effective horse-power of the Pelton wheel. Also show the diameter of the nozzle to deliver the required quantity of water on to the wheel. 2. The value of bullion got from a mine was £20,146 10s. 3d. For every 1 oz. 5 dwt. of gold in the bullion there was 10 oz. 6 dwt. of silver. Taking the value of the gold to be £4 3s. 6d. per ounce, and of the silver 2s. sd. per ounce, required the weight of the gold, and also of the silver. 3. If 25 men and 10 boys did a certain quantity of work in 17 hours, how long would it take 4 men and 12 boys to do the same quantity of work, allowing each boy to do eleventh-sixteenths of a man's work ? 4. If a sphere contain 6,540 cubic ft., required its diameter. 5. A multitubular steam-boiler is 70 in. in diameter, and it has sixty tubes 4 in. in diameter ; the steam-space is 21 in. high above the water-line; the total length of the boiler is 16 ft. : .required the area of the steam-space, and also the area of the heating-surface of the tubes.

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