On the modes of extracting gold from its ores / John Percy.

  • Percy, John, 1817-1889.
Date:
[1852]
Catalogue details

Licence: Public Domain Mark

Credit: On the modes of extracting gold from its ores / John Percy. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    WEEKLY EVENING MEETING, Friday, May 28. William Pole, Esq., M.A., F.R.S., Treasurer and Vice-President, in the Chair. John Percy, M.D., F.R.S., LECTURER ON METALLURGY AT THE GOVERNMENT SCHOOL OF MINES, &C. / On the Modes of Extracting Gold from its Ores. Dr. Percy began by stating that it was not his intention to touch upon any of those very interesting and important questions,— the dis- tribution of Gold upon the earth’s surface; the geological features of the regions which are believed to be indicative, not to say charac- teristic, of its presence; or the probable economical effect which the present unexampled supply may be expected to produce. To treat these subjects satisfactorily would require very much more time than that allotted to him on the present occasion. He should, therefore, direct special attention to certain points which he had reason to believe to be at the present time the most interesting. After a brief review of the physical and chemical properties of gold, of special importance in the consideration of the subject, the Lecture was treated as follows : — Modes of occurrence of Gold in nature. — Gold almost always occurs in nature in the metallic state; not pure, but alloyed with silver in various proportions and with the occasional addition of small quantities of iron and copper. A table* was presented, shewing the composition of native gold from various parts of the world. The presence of silver is constant with one or two rare exceptions; and its proportion varies not only in native gold from different auri- ferous districts, but even in specimens from the same locality. In Hungary gold is met within combination with Tellurium. Native gold occurs crystallized and amorphous in small grains of greater or less size, in lamina, and sometimes in masses of the weight of many pounds. Matters associated with native Gold.— These are various, such as quartz, either massive, or in a state of fine division as siliceous sand,—clay,— frequently certain kinds of iron pyrites,— rarely galena, &c. It seems doubtful whether in every instance the gold occurring in association with iron pyrites is wholly in the metallic state.— Spe- [* The Members are referred, for many of the tables and diagrams illustrating this discourse, to Dr. Percy’s Lecture, forming one of “ The Lectures on Gold, delivered at the Museum of Practical Geol gy,” published by Bogue, price 2s. Gd.]