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This eBook from the Gutenberg Project consists of approximately 111 pages of information about Scientific American Supplement No. 819, September 12, 1891.

Quantities of refractory ores treated by this process are said to have demonstrated that the whole of the gold in the ore is extracted.  The successful outcome of these trials is stated to have resulted in the Anglo-French Exploration Co. acquiring the right to work the process on the various gold fields of South Africa.  It is anticipated that the process will thus be immediately brought to a test by means of apparatus erected on the gold fields under circumstances and conditions of absolute practical work.  As is well known, gold-bearing ores in South Africa which are below the water line are, by reason of the presence of sulphur, extremely difficult to deal with, and are consequently of small commercial value.  The gold in these ores, it is maintained, will, by the new process, be extracted and saved, and make all the difference between successful and unsuccessful mining in that country.

It will have been seen that the peculiar and essential features of the invention consist in subjecting every particle of the ore under treatment to the process in all its stages instead of in bulk, thereby insuring that no portion shall escape being acted upon by the gases and the absorbing metal.  This is done automatically and in a very rapid manner.  It is stated that this method of treatment is applicable to all ores, the most refractory being readily reducible by its means.  The advantages claimed for this process are:  simplicity of the apparatus, it being practically automatic; that every particle of the ore is separately acted upon in a rapid and efficient manner; that the apparatus is adaptable to existing milling plants; and that there is an absence of elaborate and expensive plant and of the refinements of electrical or chemical science.  These advantages imply that the work can be done so economically as to commend the new process to the favorable consideration of all who are interested in mines or mining property.—­Iron.

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REFINING SILVER BULLION.

A number of years ago the author devised a method for refining silver bullion by sulphuric acid, in which iron was substituted for copper as precipitant of silver, the principal feature being the separation of pure crystals of silver sulphate.  A full description of this process may be found in Percy’s Metallurgy, “Silver and Gold,” page 479.  The process has been extensively worked in San Francisco and in Germany in refining bullion to the amount of more than a hundred million dollars’ worth of silver.  Its more general application has been hampered, however, by the circumstance that the patent had been secured by one firm which limited itself to its utilization in its California works.  The patent having expired, the author lately introduced a modification of the process by which the apparatus and manipulations are greatly cheapened and simplified.  In the following account is given a short description of the process in its present shape.

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