METALLURGY. 



which the tension is exactly measured by 

 means of specially designed dynamometers or 

 draw-vices. Copper-wire requires very care- 

 ful handling. Flaws, indentations, scratches, 

 and kinks, act very much in the same way as 

 diamond scratches on glass. The continued 

 application of heat must be avoided, for it soft- 

 ens and weakens the wire ; therefore, quick 

 soldering is essential. In consequence of its 

 freedom from magneto-electric inertia, or self- 

 induction, the speed on a copper aerial line 

 should be at least three times that on an iron 

 one. The phosphor and silicon bronzes, also, 

 when of high conductivity, are nearly pure 

 copper, and may be classed with copper. 



The Sudbtiry copper-deposits in Canada oc- 

 cur, according to Mr. J. H. Collins, in Huro- 

 nian rocks. The ore exists in three distinct 

 forms, viz., as local impregnations of siliceous 

 and feldspathic beds of clastic origin, in the 

 form of patches and strings of cupreous pyr- 

 rhotite; as contact-deposits of the same ma- 

 terial lying between the impregnated beds and 

 large masses of diorite; as segregated veins of 

 chalcopyrite and of nickeliferous pyrrhotite, 

 filling fissures and shrinkage-cracks in the ore- 

 masses of the second class. The author con- 

 siders the first original, or of high antiquity, 

 while the latter two are due to segregation, 

 produced either by intrusion of diorite or by 

 internal movements. The copper can not be 

 extracted so cheaply by the wet method as 

 from the Rio Tinto ore, and the ore is of no 

 avail as a source of sulphur. Nickel is every- 

 where present in the cupreous pyrrhotite, and 

 is of no advantage to the smelter. 



Tin. The tin-mines of Kwala Kawsar, the 

 capital of Perak, cover an area of several square 

 miles, and are worked wholly by Cantonese in 

 the most primitive manner. After washing 

 the sand, one man takes up the minute por- 

 tions of tin, which have the appearance of 

 points of black-lead, and which sink at once to 

 the bottom of the trough ; others pick out 

 stones from the gravelly mixture; others, 

 again, push up the heavier portion of the mud 

 from which the lead is not yet completely 

 separated, so that it may pass through the 

 water again and nothing be lost. The ore is 

 then washed once more in special washing- 

 houses, and is thrown, with charcoal, into a 

 simple furnace like a barrel standing on end, 

 and made chiefly of clay. The molten lead 

 oozes down through the charcoal and escapes 

 through a hole in the bottom into a pit hol- 

 lowed out of the ground, while the tin is left. 

 The tin-molds are simply holes pressed into 

 the sandy floor by circular wooden rollers, 

 each consisting of half a section, with broad, 

 wooden lips, which have indentations similar 

 in shape to to the blocks of tin shipped abroad. 

 The tin is left here for several days to cool, 

 when it is hauled out with a long iron rod and 

 dashed with water. It is curious that the only 

 tin-mine in Perak supplied with adequate ma- 

 chinery and worked by Europeans fails to give 



a profit, while the Chinese, with their primi- 

 tive methods, can turn the most unpromising 

 mine to advantage. 



In a recently patented process for the manu- 

 facture of tin plates of great length, the sub- 

 stratum is of steel, which, first rolled hot and 

 then cold, is gradually reduced to the required 

 thickness. The surface of the metal is next 

 scoured, and then, in the form of a continuous 

 plate, it is fed into a bath of molten tin. After 

 the metal has in this way received a coating of 

 tin on both sides it is passed between high- 

 ly polished rolls under immense pressure, by 

 which means the tin and steel are so consoli- 

 dated together that the finished plate is supe- 

 rior in every respect to the ordinary article. 



Argentine is a name given to tin precipitated 

 by galvanic action from its solution. It is usu- 

 ally obtained by immersing plates of zinc in a 

 solution of tin containing six grammes of the 

 metal to the litre. In this way tin-scrap can 

 be utilized. To apply the argentine a bath is 

 prepared from argentine and acid tartrate of 

 potash rendered soluble by boracic acid. Pyro- 

 phosphate of soda, chloride of ammonium, or 

 caustic soda may be substituted for the acid 

 tartrate. The bath being prepared, the objects 

 to be coated are plunged therein, having first 

 been suitably pickled and scoured, and they 

 may be subjected to the action of an electric 

 current; but a simple immersion is enough. 

 The bath for this must be brought to boiling, 

 and objects of copper or brass, or coated with 

 those substances, may be immersed in it. 



Gold. A specimen of the mineral called 

 "black gold" or maldonite, from the "Nug- 

 gety Reef," Maldon, Victoria, has been ana- 

 lyzed by R. W. Maclvor. It is described as 

 being without crystalline character and malle- 

 able, and having a bright silvery white luster 

 when freshly broken, which slowly tarnishes 

 on exposure to the air till it ultimately be- 

 comes nearly black. The composition of the 

 mineral was found to be : 



Gold... 64-211 



Bismuth 34'398 



Siliceous matter 1 '891 



Total lOO'OOO 



If the silica be omitted and the metnls calcu- 

 lated to make 100, the results would indicate 

 for the mineral the formula Au 2 Bi. 



Several advantages are gained by extracting 

 gold from its ore with a dilute solution of cal- 

 cium chloride mixed with an equal amount of 

 dilute acid, instead of with chlorine gas, as in 

 Plattner's process. The chlorine apparatus and 

 the labor employed for generating the gas are 

 dispensed with. The solutions employed be- 

 ing much diluted, there are no noxious fumes 

 to affect the health of the workmen. The gold 

 is dissolved uniformly and completely. The 

 method is applicable when the ore contains 

 silver in addition to the gold. It has been in 

 use since 1885 at the Falun copper-works in 

 Sweden. 



