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Show MINING REVIEW. INTER-MOUNTA- IN A Snake River Dredge. 5 ty of one hundred horse power, a will account for about 75 per cent of the Westinghouse compound engine, which contents. What the remainder is comThe Snake river placer problem is one drives a seven-focentrifugal pump, posed of is not known. ten-inc- h a with in the mining world. of great interest discharge, and a caPossibly this is a new mineral, as 8000 of from features other and distinctive pacity plagallons per minute, Its there does not seem to be anything an 200 to new handle a of its and it make cers ability question, yards gravel in mineralogy that approaches it in hour. is so new It creation of the renders constructed as to composition. per solutions Much thought dredge the river bottom or sluice the appliances necessary. and means have been devoted to this banks with equal facility The gravel The Chemical Assay. is to down contrivances fine containthe sand grilled entirely purpose. Many on fields fail in other these. successful ing the values, which passes over a sysBY JAMES W. NEILL. One essential requirement of any tem of forty-eigamalgam pans, Prof. Hirsching, in his criticism on Snake river appliance is the possibility which is equal to the capacity of the remarks about the chemical assay, of gathering the flour gold, so abun- machine in full operation. Its present my takes for granted that I am ignorant dant in its bars, which by the attrit- location is at a bar of 280 acres, or an of the several chemical which ion of ages of rolling and washing and average value of $1.50 per yard of pay he names. Had the methods known grinding of the gravel and rocks has grvel. It can be operated continuously, that I hold a diploma professor as mining enginbecome so inflnitessimal as to be in- regardless of weather conditions when eer and metallurgist (Berg and Huet-te- n visible to unaided sight. From its orig- desired. It promises fortunes to its Ingenieur) from the Royal Prus-sio- n inal flaky condition it has become promoters, and the results are looked to Mining Academy of Clausthal in ground into dust and must be treated with much interest by placer miners. the Hartz, where I studied chemistry from this standpoint. A distinctive under the celebrated Hampe, he would A Remarkable Ore. characteristic of it is the tendency to probably not have accused me of ignorfloat in washing and be carried away : A remarkable rich and peculiar min- ance of the methods mentioned. in the sluice. A number of machines eral has been encountered in the lower I am, of course, familiar with these methods; they are one and all volumetot ht : ric methods and are excellent ones for the materials upon which they are usually applied, i. e., silver bullion or alloys. In no single one of all these volumetric tests is the gold determined volumetrically, and in no single one of these methods is the silver value of a crude ore determined direct, as is done by - the fire assay. is useless to quote as an answer to my question, What is the chemical y, the usual determinations of copper, iron, lime, lead, zinc, etc., which It as-sa- are now scarcely called classed as analysis. assays, but However, considering these all as chemical assays, does the professor wish me to believe that any known chemist can carry on any of these well-knodeterminations with such accuracy that he can tell the difference between .0018 and .0018 per cent? And these figures represent the difference between $10 and $1 per ton in gold wn esti-natio- n! A SNAKE RIVER DREDGER. are now in operation between American Falls and Huntington, designed especially for gathering this gold, most of which are in a measure successful, but no one reaching an absolutely satisfactory standard of perfection. It is the design of The Mining Review to investigate as many of these appliances as possible and give the leading features of their operation for the benefit of its readers. To this end we have selected the Chicago Dredge companys boat, nowT located as Cass bar, near the point where the Snake river crosses the Oregon line. It is under the management of Mr. E. H. Lewis, who is largely interested financially in the enterprise, besides controlling many of the patented appliances in its construction. It consists of a boat 30x60 feet in size, of tons displacement, upon which is erected powerful machinery of approved pattern. It has a boiler capaci- - Griffith mine at Georgetown, Colo., says the Courier. workings of the It occurs irregular patches in and or more in thickness, in iron and copper pyrites. The mineral is undoubtedly homogeneous, seams a half-inc- h and not a mixture. It is of fine gran ular structure, has a conchoidal fraccolor ture, and is of light steel-gra- y and bright metallic luster. The streak is slightly darker than the color. In hardness it ranks about 2, or softer than silver glance, and is very brittle. It has a greasy feel and leaves a gray trace on paper. Under the blowpipe it melts quickly into a malleable globule. An assay gave the following result: Silver Gold 11,478 ozs h9$0ZS p. c .ij P c It was found that the mineral also carries a small percentage of tellurium and iron and considerable sulphur. The above assays with sulphur estimated Lead Copper There was no intention on my part to decry the chemical process as applied to the extraction of gold from the ores on a large scale; nor did I claim the cyanide process as the only one worthy of consideration, but used the illustration of the losses made in this process on a large scale merely to emphasize the comparison with the fire assay results. Also, because the chemical assay is usually a cyanide I am willing and anxious to learn, and if Prof. Hirsching will give The Reviews readers a minute description of the method used in the cyanide gold assay, I will be glad to study the same. as---sa- y. The New York Mining Exchange was organized last week by the election of the following officers: Dr. William Brandreth, president; F. B. Wilson, William Brandreth, treasurer; M. E. Wooster, secretary. Fifty prominent Wall street men, it is said, have joined the new organization, which, it is hoped, will be more deserving of success than its late unlamented predecessor. The first 100 members will pay a fee of $100, when it will be raised to $250. The secretarys address is 30 Broad street, room 1222. vice-preside- nt; |