486 



METALS. 



A process for bronzing cast-ifon, by means 

 of which copper is made so closely adherent 

 that, if chipped off, it takes a scale of iron 

 with it, is also a recent Paris invention. The 

 operation consists in first scouring and then 

 dipping the articles that are to be coppered 

 into a bath of melted chloride or fluoride of 

 copper and cryolite, to which chloride of ba- 

 rium is added. The deposit of copper is per- 

 fectly even, not being thicker in the salient 

 parts than in hollows or under-cuttings. A 

 number of large statues have been covered 

 with copper at Val d'Osne, and, among other 

 works, two bulls, larger than nature, present- 

 ing each a surface of at least one hundred and 

 thirty-two square feet, and with invariable 

 success. Some of these objects have been ex- 

 posed to the air, during one summer and two 

 winters, without suffering any injury. The 

 copper deposited on the works is never less 

 than -^ of an inch in thickness. The cost 

 of the ornaments is not more than doubled by 

 this application, and the copper, when care- 

 fully treated by a French bronzist, presents an 

 appearance very little inferior to true bronze. 

 The same process is applicable to the tinning 

 of copper or cast-iron vessels ; the adherence 

 of the two metals is complete, and the coating 

 of tin may he laid on any desirable thickness. 



Purification of Quicksilver. A new process 

 for freeing quicksilver from the soot and other 

 foreign matter which becomes mingled with 

 it during the operations of condensing and re- 

 ducing, has been adopted at the new Almaden, 

 and other California mines. The apparatus is 

 the invention of Mr. J. B. Randall and Mr. 0. 

 W. Wright. The draft which carries the mer- 

 curial fumes from the furnace where the ore 

 is roasting, into and through the condensers 

 takes with it a mixture of fine dirt, particles 

 of carbon, some ash, some nndecomposed cin- 

 nabar, with various other impurities. These 

 are deposited in the condensers in a condition 

 resembling lamp-black or paste, having been 

 moistened by the steam arising from the fuel 

 and the ore, and as a consequence they be- 

 come intermingled with the quicksilver. The 

 impure quicksilver is placed in an iron tank, 

 and hot water is added, and the two intimate- 

 ly mixed. Wood-ash or other suitable alkali 

 is added, which exerts a further purifying ac- 

 tion. The quicksilver is then drawn off. The 

 apparatus can be kept running continuously, 

 and all the quicksilver is saved by the process. 

 A New Steel. A new compound metal, the 

 invention of Mr. Atwood, of Pittsburg, Pa., 

 has been brought into notice during the year. 

 It is made of cast, wrought, and scrap iron, 

 that are melted and united in the presence of 

 a flux that may consist of either carbonate of 

 lime, quartz rock, or any of the silicic-acid 

 compounds that are free from alkali. The 

 combination of the ingredients forming the 

 compound metal may be effected in crucibles, 

 or in furnaces of most any form in which the 

 requisite degree of heat can be obtained. The 



proportion of the ingredients to be employed 

 will vary somewhat, however, according to the 

 means or apparatus used for making the com- 

 bination. When melted and combined in a 

 crucible, cast and wrought iron are combined 

 in equal parts, but, if a cupola furnace is em- 

 ployed, the proportions are five-eighths of cast- 

 iron to three-eighths of wrought-iron. The 

 scrap may be added in any desired proportion 

 to these ingredients. When a combination is 

 conducted in a gas or air furnace, three-eighths 

 of cast-iron, four-eighths of wrought iron, and 

 one-eighth of scrap or old iron, are used. The 

 product, according to the inventor, possesses 

 many of the properties of steel. It is easily 

 annealed, may be hammered, tempered, and 

 fashioned into any desired shape, without 

 crumbling or breaking, as is the case with or- 

 dinary malleable castings. It ig sufficiently 

 hard for all practical purposes, and is entirely 

 free from porosity. 



New Method of Treating Mixed Copper, Sil- 

 ver, and Gold Ores. An important modifica- 

 tion of the Hunt and Douglas copper process, 

 by which it is made applicable to the produc- 

 tion of gold and silver, is thus described in the 

 Engineering and Mining Journal : 



That the presence of copper in solution as chlo- 

 ride assists the extraction of silver from its ores is a 

 fact which is well known and taken advantage of; 

 but the peculiarity of the new process consists in 

 using with the salt a solution of neutral protochlo- 

 ride of iron instead of copper pyrites or bluestone. 

 Both chloride and dichloride of copper convert the 

 sulphuret of silver into chloride of silver, but their 

 use as reagents in the extraction of silver has hith- 

 erto been limited by their cost ; if, however, these 

 chlorides of copper can be obtained from the copper 

 ores which are often mixed with the ores of silver, 

 an important reagent is obtained without cost, while 

 the copper is saved and becomes a valuable by-prod- 

 uct instead of being objectionable. To secure these 

 advantages, Messrs. Douglas, Hunt & Stewart treat 

 silver ores containing copper with a bath of proto- 

 chlpride of iron, which reacts with oxide of copper, 

 giving rise to chloride and dichloride of copper, the 

 latter of which, like chloride of silver, though insol- 

 uble in water, is soluble in brine. The essential 

 features of the new process are the choice of suita- 

 ble ore, and the grinding, calcining, and chloridizing 

 of it ; the treatment of the oxydized or. chloridized 

 ore with a solution of protochloride of iron and salt, 

 in order to dissolve out the copper and most of the 

 silver, and the precipitation in the metallic state of 

 the copper and the silver thus dissolved ; the lixivi- 

 ation of the sands thus deprived of their copper and 

 part of their silver, with hyposulphite of'lime to ex- 

 tract the remaining silver, and the precipitation of 

 the silver thus dissolved by sulphide of calcium ; 

 and, if gold be present, leaching the sands exhaust- 

 ed of copper and silver with chlorinated brine and 

 the precipitation of the dissolved gold from this by 

 sulphuretted hydrogen or sulphide of calcium. 



In this method of extracting silver the only rea- 

 gent consumed is the protochloride of iron. The 

 advantages of the system are numerous. In chlo- 

 rinating in the furnace silver ores containing base 



Jr,r v **.. v*. A* \si_t,j UJ.LU. om/ocv^nciiu ti cat 111 cut witii tiic 



bath of protochloride of iron. All the copper is re- 

 covered at a slight cost. As much copper is extract- 

 ed from unroasted copper ore or regulus as is con- 

 tained in the state of protochloride in the solution 



