87

a—2

Subject B. — -A malgamaiing-machines. 1. What is meant by " amalgamating-machines " ? Why are they required ? Describe the class of ore most suitable for treatment by these machines. 2. Describe the different amalgamating-machines used in the Dominion of New Zealand State their capacity, the speed they are worked at, and the quantity of quicksilver used in each machine are thiylsed™ 6 7 "" ** con « d > a »* ™der what circTmstances Subject O.—The Use of Quicksilver, and Methods of using it in connection with the Extraction of Gold and Silver from Ores. L Ho ln d d o -sirv U er a ores t f n quicksilver is in a fit state to use in the amalgamation of gold2. Is there any advantage in using common salt and sulphate of copper in amalgamating-machines - Describe how they are used, and the class of machine suitable for their use mdcmnes • 3. How are copper plates coated with quicksilver ? How is the amalgamated bullion taken off and how is the plate kept in a fit state for amalgamation ? 4. If the quicksilver contained base metals such as lead, antimony, and zinc, how would you purify the quicksilver so.as to make it in a fit state for the amalgamation of gold and silver - 5. Describe how bullion is extracted from quicksilver and made into a marketable commodity. Subject D.-Cyanide, Chlorination, and other Chemical Processes of recovering Gold and Silver from Ores. 1. Describe the class of auriferous ore most suitable for treatment by the chlorination process, and state how it is prepared for treatment. v ' 2. What is meant by chlorination ? How is it produced ? Describe the process fully, and state by what means the gold is extracted. J y 3. Give a neat sketch of a modern plant where ores are treated with KCN solutions • also describe the class of ore most suitable for treatment by this process. 4. How is KCN solution prepared ? 5. How is the strength of KCN solution ascertained ? 6. How would you ascertain the most suitable strength of KCN solution to use for the class of ore required to be treated ? 7. In making up 40 tons of a sump solution containing 0-013 per cent, of KCN to a 0-2-per-cent solution, how many pounds of crude cyanide containing 78 per cent. KCN would be required - ' 8. In using 50 tons of sump solution containing 0-1 per cent, of KCN to make up a 0-23-per-cent solution, how many tons of a 2-per-cent. solution of KCN would be required - 9. tonsj,f a 0-18-per-cent. KCN solution would be obtained from 7 tons'of a 6- P er-cent. 10. Give the solubility of lead, antimony, copper, and zinc in relation to the solubility of gold, and state ntt f "ii . f ,T talS ™ °? the treatment of auriferous ores by KCN solutions. 11. Howu bullion extracted from KCN solutions and made into a marketable commodity ? Describe 12. If any of the workmen suffered from hydrocyanic poisoning, what remedy would you apply ? Subject E.— The Sampling and Testing of Ores. 1. Sketch a combined coke-fusion-furnace and sampling drying-furnace, the fusion-furnace to be o w. c fP able (( of takm § 81X H size Battersea round crucibles at one time. Give all dimensions 2. What is a grading test, how is it carried out, and why is it used « 3 ' Defi a n e o! Le tfrn/'stendard" gold? A bar of bullion weighs 242 oz. 12 dwt. 16 <*r and a°savs 9234: what is its "standard" weight? b JS 4. In a " sands " residue sample as taken from a vat, state how you would determine the following • («) Total gold (6) dissolved gold, (c) undissolved gold. Give only outline of processes used ' 5. riow is the amount of sulphur m pyntic concentrates determined ? 6. State how the amounts of gold and silver respectively in a sample of zinc-gold slime are determined - Give outline only of process. 7. An ore consists of 80 per cent, quartz, the balance being alumina, lime, and pyrite. Taking 2 assay tons of ore for assay, what fusion charge would you employ? And state why you select the different ingredients m the proportions given. Subject P.— A Knowledge of Arithmetic and the Method of keeping Battery Accounts. 1. The value of bullion containing gold and silver amounted to £4,977 10s fid • 121 r, Pr „ fflf nt the weight of the bullion was gold. Taking gold to be £4 Is. per ounce/and silver 2s 3d per ounce, what would be the weight of the gold and silver in the bullion ? 2. faking the specific gravity of silver to be 10-5 : required, the weight of a sphere of silver 4ft in diameter in pounds troy. "' m 3 ' Ho^fTtKe b inglo0 0 f f t.T ater WOUM a n ° ZZle 2im - m diamet6r diSoharge P er minute ' the head 4. The wages of a crushing-battery, in which 54 men were employed, amounted to £280 per week These men were in three equal divisions. A division got 63 per cent, of the B division got 80 per cent, of the wages of A division, and the balance was equally divided among the men in C division. How much did each man receive'? 5. Extract arithmetically the cube root of 0-0000312.