This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 edition. Excerpt: ... CHAPTER TIL LABORATORY EXPERIMENTS. The cyanide process is essentially a chemical one, and a commodious and well-equipped laboratory forms one of the most important and necessary parts of the whole plant. It is the duty of the metallurgist in charge to determine by actual experiment the lowest strength of cyanide solution to extract an adequate percentage of the gold, and also to devise means of overcoming the problems which are inseparable from the treatment of different classes and grades of ore, with so active and subtle a compound as potassium cyanide. The testing and valuing of the ores before, during, and after treatment must be entrusted to a careful and trustworthy assayer. The testing and making up of the working solutions are very simple operations, that may be left to experienced and intelligent workmen who possess a knowledge of arithmetic extending as far as decimals. With free-milling gold ores the actual working extraction will generally be as high as that obtained in the laboratory, but too much reliance must not be placed on the laboratory experiments in the case of ores containing copper or antimony. The author, s experience is that high extractions may be obtained in the laboratory from ores totally unsuited for treatment by the cyanide process on a working scale. The conditions on the one hand are theoretical, on the other actual, and before adopting the cyanide treatment for a sulphide or mineralized ore, working experiments should be made on parcels ranging from two to five tons, in order to ascei-tain the consumption of cyanide and actual extraction. If the working trials are successful the cyanide treatment may be adopted with confidence. On the other hand, in the case of an ore containing comparatively coarse..