METALLURGY. 



485 



The South African gold-fields have been 

 growing in importance, with the almost daily 

 discovery of new "reefs." The exports of 

 August, 1887, from the district of Johannes- 

 berg, were valued at 40,000. The gold region 

 is supposed to extend for 600 miles over the 

 line of country between Kimberly and Dela- 

 goa Bay. So far, the gold is mined from the 

 " reef" or rock fountain, and has to be extract- 

 ed by the aid of crushing-machinery ; and, as 

 yet, no large alluvial deposits have been found. 



Nickel. The composition used principally 

 'for the electro-deposition of nickel in the pro- 

 cess as described by Mr. Thomas T. P. B. 

 "Warren, is a double sulphate of nickel and 

 ammonia. The silvery appearance of the 

 deposit depends on the purity of the salt as 

 well as on the anodes. About eight ounces of 

 the double sulphate to each gallon of distilled 

 or rain water, is a good proportion to use when 

 making up a bath. The bath should be neu- 

 tral, or nearly so. slightly acid rather than 

 alkaline. To produce a bright deposit, the 

 author uses a very small quantity of bisulphide 

 of carbon in his mixture; but if much is used, 

 as in silver plating, the deposit is made very 

 dark, almost black, and can not be buffed or 

 polished bright. 



The nickel-mines at Thio, in New Caledonia, 

 are situated on the left bank of the river of 

 that name, and extend over an area of about 

 6,000 acres. The lodes now being worked 

 vary in thickness from three to seven feet, and 

 are exploited in large open cuts or quarries. 

 The ore contains, on the average, about 10 per 

 cent, of pure nickel. Mr. Croisille, who re- 

 ports upon the mines, estimates that, with the 

 new machinery and generally increased mining 

 facilities, there will be no difficulty in extract- 

 ing sufficient ore to provide for the manufact- 

 ure of two or three thousand tons of the pure 

 metal per annum. 



The Ferro-Nickel Society of Paris is making 

 a nickel steel, composed of soft iron, nickel, 

 manganese metal, or an oxide of it, aluminum, 

 and ferro-cyanide of potassium, which requires 

 no hardening. The steel is produced at one 

 melting. 



Antimony. Some of the richest antimony- 

 mines in the world exist within a few miles of 

 Oporto, in Portugal. They have been worked 

 for many years on a small scale. A Portu- 

 guese company was lately formed, with a capi- 

 tal of 100,000 to work them ; and it has al- 

 ready declared a dividend of 10 per cent., be- 

 sides adding a very substantial sum to the 

 reserve fund. Adjoining this mine is one that 

 has been worked by English residents of Opor- 

 to (the Corgo mine) which, having been bought 

 by English capitalists, is now undergoing de- 

 velopment. A lode has been struck which 

 varies from 7 inches to 3 feet 3 inches in 

 thickness, with a metallization of pure antimo- 

 nial lead. Six distinct lodes in the Corgo mines 

 have been opened and exploited to a consider- 

 able extent. 



Ores containing a low percentage of sulphide 

 of antimony are treated by Messrs. Parnell and 

 Simpson, of Chester, England, by reducing 

 them to a fine state of division, and agitating 

 with a solution of monosulphide of ammonium, 

 with or without heat. The sulphide of anti- 

 mony becomes converted into a red sulphide, 

 held in suspension in the liquid, and is sepa- 

 rated by drawing off and afterward washing 

 the settlings of gangue and unaffected ore. 



Zinc. Zinc - ores are found in larger or 

 smaller quantities in most of the counties in 

 Missouri south of the Missouri river gener- 

 ally in conjunction with lead. In Franklin, 

 Crawford, Jefferson, and Washington counties, 

 zinc occurs disseminated along with lead, in 

 immense bodies of barytes. The richest de- 

 posits of zinc are on or near the Ozark mount- 

 ains. The principal part of the mining is 

 done in the southwestern counties. The ores 

 comprise a considerable variety of carbonates, 

 silicates, and sulphurets. Outside of this dis- 

 trict, zinc-mining proper may be said to be 

 comparatively unknown; but in "Washington 

 and other counties where the ore is exposed to 

 view over large areas, the metal is worked on 

 the surface in the most rudimentary fashion 

 to a large extent by farmers at times when 

 their proper work is not pressing, who thus 

 find a convenient means for increasing their 

 income. The ores are mined in some of the 

 eastern counties in small quantities, but not 

 profitably, on account of the crudeness and ex- 

 pensiveness of the processes employed, for a 

 furnace in South St. Louis. The oxide of zinc, 

 or zinc-white, an important pigment, was for- 

 merly manufactured with profit at works in 

 Washington County. But the works, which 

 consumed about ten tons of ore a day, had to 

 be suspended on account of the difficulty of 

 securing a sufficient supply of ore. 



In a new process for extracting zinc from 

 blende, as proposed by Messrs. Hannan and 

 Milburn, of Glasgow, the ores, instead of being 

 roasted, are pulverized, mixed with malleable 

 scrap-iron, and then subjected to distillation in 

 a vertical iron retort attached to a condenser. 

 In this process the lead and copper which zinc- 

 blende frequently contains are obtained in com- 

 mercially valuable forms. 



Processes. Electricity has been applied effi- 

 ciently to the treatment of ores at the Douglass 

 Mill, Dayton, Nevada. The method was at 

 first tried on tailings, with a view of recover- 

 ing the mercury which had been lost ; but it 

 has been found still more effective in working 

 ores by preventing loss of mercury and amal- 

 gam. The dynamos in use at the Douglass 

 Mills are capable of operating seven settlers. 

 The mill works 135 tons of ore per day. It is 

 represented that the decrease in the cost of 

 chemicals for a silver mill is equivalent to twice 

 the cost of treatment and power when the new- 

 process is used ; and that in the Douglass Mill 

 it has cut down the cost of chemicals one half, 

 and does better work. 



