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4. How do you ascertain the strength of KCN solutions to satisfactorily treat the particular class of ore you have to deal with ? 5. In making up 30 tons of a sump solution containing 0-01 per cent, of KCN to a 2-5 solution, how many pounds of crude cyanide containing 75 per cent, of KCN would be required ? 6. In using 40 tons of a sump solution containing 0-03 per cent, of KCN to make up 2 per cent, solu- , tion, how many tons of 3 per cent. KCN would be required ? 7. How many tons of 1-6 solution would be required to make up 20 tons of a 0-2 solution using 0-02 of a sump solution ? 8. How is KCN solution prepared ? State fully. 9. A vat 30 ft. in diameter contains pulverized ore to a depth of 5 ft. 3 in. : how many tons of ore would it contain, allowing 70 cubic feet to the ton ? Also, what quantity of KCN solution would be required to treat this amount of ore ? 10. Describe the effect ores containing lead, antimony, zinc, and copper have on the treatment of auriferious ores containing these metals, by KCN solutions. 11. If a workman suffered from hydrocyanic poisoning, how would you treat him, and what antidote would you apply ? 12. What effect (if any) has chlorine-gas on the workmen if they inhale it, and what remedy would you apply ? Subject E.— The Sampling and Testing of Ores. 1. A gold-silver ore-sample weighs 5 lb., and is found to contain " metallics," the amount of which in the sample weighs 0-078 grain bullion ; this bullion on parting is found to contain 0-024 grain of gold ; an assay of 1 A.T. of the sample (free from metallics) gives bullion 9-32 milligrams, containing 2-65 milligrams gold : how would you report the results so as to show the amounts and values of gold and silver respectively per ton ? (Gold, 84s. per ounce ; silver, 2s. per ounce). 2. What precautions have to be taken in determining the amount of moisture in a bagged lot of pyrite concentrates, and why ? 3. Describe a method of assaying a gold cyanide solution for gold. 4. A sample of tailings has been tested for cyanide-consumption, and shows an excessive amount: what tests would you make to determine the likely cause or causes of such consumption ? 5. A sample of tailings fron a cyanide plant has been assayed for gold, and shows a high assay ; it is assumed that this result is owing to the ore not being crushed fine enough : how would you, as an assayer, proceed to determine whether such is the case or not ? 6. How would you assay a sample of gold-amalgam for gold only % (Give outline only of process). 7. A bar of bullion weighs 472 ox. 9 dwt., and assays 927. State the following : (a) Fine weight of bar; (b) "standard" weight of bar; (c) value of bar. 8. Describe the preparation of pure silver from waste silver-chloride of the assay laboratory, Subject F. — A Knowledge of Arithmetic and the Method of Imepdng Battery Accounts. 1. The wages in connection with a crushing-battery and cyanide plant amount to £560 a month of 24 days, 40 men being employed at different rates —the A division are paid £14 Bs. per man ; B division, 20 men, 90 per cent, per man of the amount paid to each of the men in A division ; the C division, 13 men, 106 per cent, of the amount paid to each man in B division ; and the balance is paid to 3 men in D division : how much does each man receive per day ? 2. A certain piece of work was done by 14 men and 6 youths in 20 hours : how long would it take 4 men, 7 youths, and 4 boys to do the same amount of work, taking 4 youths to be equal to 3 men, and each boy to do three-fourths of the work to be done by each youth '{ 3. The value of bullion containing gold, silver, and copper was £6,000 ; 10 per cent, of the bullion was gold, 85 per cent, silver, and the balance copper : taking gold at £4 per ounce, silver at 2s. 2d. per ounce, and copper at £65 per ton of 2,000 lb. troy weight, what would be the weight and value of the gold, silver, and copper in the bullion ? 4. In crushing with a battery of stamps having a drop of 7 in., show by calculation how many drops per minute can be made without the tappets on the stamps' shanks falling on to the cams. 5. Square 0-00312, and extract the cube root arithmetically of the quotient.