532 



METALLURGY. 





the zinc is separated from its salt, is drawn off 

 into a chamber where it is absorbed by chalk. 

 This process is defective on account of the loss 

 of metal in smelting, and the presence of chlo- 

 rides of zinc as an impurity. In the nitric acid 

 method, an oxide is produced by the electrical 

 decomposition of the salt, and it is necessary 

 to add some organic matter, such as glycerine, 

 a gum, etc., for the removal of the oxygen. 

 To obtain enough nitric acid and organic mat- 

 ter the process has to be conducted near where 

 some chemical industries are carried on. In 

 the sulphuric- acid process, also called the Le- 

 trange process, the solution is effected by 

 means of the sulphuric acid obtained from the 

 ore itself in the process of roasting. No re- 

 agent being required, the method is independ- 

 ent of other industries, and is free from all ex- 

 pense of transportation. Though principally 

 intended for blende, it is available for all the 

 ores. It is very simple, and does net require 

 the separation of substances containing lead, 

 nor, if sulphuric acid is evolved in excessive 

 quantities, the removal of the calcareous 

 gangues. Only a moderate roasting is required 

 when only blende is treated ; but if the ore be 

 only calamine or the oxides of zinc, it is ne- 

 cessary to feed the bath with a certain quantity 

 of acid or sulphates. The sulphurous vapors 

 produced by roasting the blende may often be 

 used for this purpose. As acid is continuously 

 reproduced during the process of precipitation, 

 it will only be necessary after that is started to 

 provide as much sulphate as will furnish the 

 necessary acid to be absorbed by the foreign 

 matters, the chalk, iron, etc., contained in the 

 ore. The electrical current necessary to effect 

 the precipitation is furnished by machines driv- 

 en by steam or water power. By this process 

 the zinc contained in the ore is extracted in its 

 entirety, and pure. The cost of treatment is 

 limited to the working of the electrical appara- 

 tus, and to manual labor of the most simple 

 character. 



OOPPEE. Copper is prepared at Spenceville, 

 Oal., from a fine-grained pyrites in a kind of 

 chlorite slate. The ore, which has been pre- 

 viously broken into small lumps, is put upon a 

 base of fire- wood around a loose brick flue, and 

 piled up with layers of brush at intervals; 

 salt is distributed through the pile, tank resi- 

 due is placed on top to exclude the air, and 

 the heap is then fired. The process of roasting 

 requires six months. In the leach- vats, of 

 which there are fifty, with a capacity for 120 

 tons of roasted ore, the leaching is hastened by 

 boiling with steam. The copper is precipitated 

 with scrap-iron. 



NICKEL. Nickel-ores are quite extensively 

 distributed through the United States more 

 generally than is usually supposed. The chief 

 source of supply is at Lancaster Gap, Pa., but 

 the ores are also found in Connecticut, by the 

 Hudson River, and in New Jersey, associated 

 with chrome-ores, where they appear in the 

 shape of a coating of nickel oxide or emerald 



nickel ; also associated with magnetic pyrites. 

 Deposits have also been found in the mag- 

 nesian rock at Quebec ; at Silver Harbor, on 

 Lake Superior; in Nevada; and in Douglas 

 County, Southern Oregon. The hydrated sili- 

 cate of New Caledonia, a very pure ore, has 

 been found to be in sufficient abundance to 

 supply nearly all the works of Europe. Pro- 

 fessor Wharton exhibited at Philadelphia, in 

 1876, a number of articles that had been made 

 by him of wrought nickel. He showed them 

 again in 1878, in Paris, where they attracted 

 but little notice at first, but excited great admi- 

 ration when the attention of the judges was 

 called to the quality of the metal. Experi- 

 ments, prompted by this demonstration, were 

 immediately tried on a more extensive scale, 

 which resulted in raising the manufacture of 

 nickel to a considerable importance. Sheets 

 of iron and steel have been coated by weld- 

 ing with nickel on both sides, so as to furnish 

 a combination adapted to the manufacture 

 of many articles of hollow ware. Professor 

 Wharton has succeeded in making several ar- 

 ticles of cast -nickel, among which are the door- 

 knobs of his house in Camden, N. J. He has 

 proved that the metal will not tarnish, by ex- 

 hibiting objects which were shown at the Paris 

 Exhibition in 1878, and are as bright as ever, 

 although they have not been rubbed or polished 

 since. A French company is making a con- 

 siderable variety of useful articles from the 

 nickel of New Caledonia. Mixed with zinc, 

 copper, or tin, in such a proportion that it 

 shall constitute 20 per cent of the combination, 

 this metal forms an inoxidable nickel bronze ; 

 a material of which all articles that are now 

 made of brass or copper, and nickel-plated, 

 may be made at practically the same cost, 

 while they will be one fifth stronger and may 

 be as much lighter. Added to steel, nickel in- 

 creases its hardness, renders it inoxidable, and 

 makes it more suitable for edge-tools. 



MICKOSCOPIOAL ANALYSIS OF IKON AND STEEL. 

 Dr. H. 0. Sorby, F. R. S., has recently made 

 known the results of some interesting investi- 

 gations he has been making in the microscopi- 

 cal structure of iron and steel. His specimens 

 were prepared for examination by polishing 

 very thin plates of the metal and subjecting 

 their surfaces to the action of nitric acid till 

 they were sufficiently etched to bring out the 

 details of the arrangement of the particles, the 

 development of which was due to the fact that 

 some of the constituents were not acted upon 

 at all, and others in varying degrees. As far 

 as could be learned from the careful use of the 

 microscope, various kinds of iron and steel 

 contain at least seven well-marked constituents. 

 They are pure iron ; what are probably three 

 well-marked compounds of iron with varying 

 amounts of carbon or other substances which 

 are met with in small quantities in different 

 sorts of iron and steel; portions of included 

 slag; well-marked crystals of graphite; and a 

 small crystal, which may be silicon. The 



