536 



METALLURGY. 



malleability was improved, and the specimen 

 seemed to be sensibly less hardened by ham- 

 mering than the metal of commerce. The 

 specific gravity was determined to be 2'^3. 



Robert L. Thomson recommends, for the 

 determination of aluminum in the presence of 

 large proportions of iron, the reduction of the 

 iron, if in the ferric, to the ferrous condition, 

 by means of sulphurous acid. Phosphoric 

 acid, or phosphate of ammonium or sodium, is 

 then added ; then ammonia till a faint perma- 

 nent cloudiness is formed ; then excess of am- 

 monia, which throws down the alumina as a 

 phosphate. The precipitate is dissolved in 

 hydrochloric acid, and an excess of caustic 

 soda is added. After boiling and filtering, the 

 filtrate is acidulated with hydrochloric acid, 

 and an excess of phosphoric acid or phosphate 

 of ammonia or soda. The normal phosphate 

 of aluminia is then precipitated by means of 

 ammonia. 



Alloys. According to Prof. W. Chandler 

 Roberts, of the Royal Mint, the term alloy is 

 usually applied in ordinary language to the 

 mass formed by mixing a base metal with a 

 precious one, while in scientific language it 

 indicates the base metal which is added. Al- 

 loys are used in preference to pure precious 

 metals for various reasons, chief among which 

 is the fact that they are harder and more 

 durable. When a base metal is to be chosen 

 for mixture with a precious one, it should be 

 borne in mind that the resulting alloy must 

 have the qualities of good color, ductility, 

 and freedom from brittleness. Silver forms a 

 very ductile alloy with gold, but lowers the 

 color, while copper forms a durable as well as 

 a ductile alloy, and lightens the color. At the 

 mint, the qualities sought as most desirable 

 in an alloy are: 1. Ductility; 2. Durability; 

 and, 3. Uniformity of composition. The alloy 

 is, besides, expected to be sonorous, and to 

 possess the degree of viscosity which will en- 

 able it to flow under pressure into all the fine 

 lines of an engraved die, while the metal must 

 be rigid enough to'retain its impression when 

 submitted to rough usage. The fineness of 

 alloys of silver is computed with reference to 

 the troy pound. The computation in the case 

 of gold alloys is based on the singular u carat " 

 system, which has within two years given way 

 at the British Mint to a decimal system. 



M. Bourbonze employs, in place of brass for 

 the internal parts of optical instruments, an 

 alloy of aluminum and tin in the proportion 

 of 10 parts of tin and 100 parts of aluminum. 

 The alloy is white, has a density of 2-85, and 

 can be soldered as easily as brass. 



Processes. Hamilton Y. Castner has de- 

 scribed his new process for the production 

 of the alkali metals, by means of which he 

 claims that a large saving is effected over the 

 old process by heating the carbonate of the 

 alkali (soda or potash) with charcoal and iron. 

 It consists in reducing either the hydrate or 

 the carbonate of the alkali, when in a fused 



state, at moderate temperatures, by the use of 

 the carbide of a metal or its equivalent. By 

 the equivalent of the carbide of a metal, the 

 author means a mechanical compound of car- 

 bon and metal, from which the metal can not 

 be separated except by the aid of acids or in- 

 tense heat ; and such a compound he produces 

 by coking a mixture of tar and finely divided 

 iron. By this means an excess of carbon is 

 avoided, and the use of lime is rendered unne- 

 cessary. The reducing substance, by virtue of 

 its composition and gravity, remains below the 

 surface, and is therefore in direct contact with 

 the fused alkali. The author prefers to use 

 caustic soda in the preparation of sodium, on 

 account of its fusibility, and with it to mix 

 such a quantity of the so-called "carbide" 

 that the carbon contained in the mixture shall 

 not be in excess of the amount theoretically 

 required to reduce all the soda to sodium. Mr. 

 Castner is able to obtain by his process fully 

 90 per cent, of metal, instead of 30 per cent., 

 as formerly. He claims that the method is 

 more simple in its details, and does not re- 

 quire the care and management necessary in 

 carrying on that now used; that, performing 

 the reduction at a comparatively low tempera- 

 ture, it saves in fuel and prevents the excessive 

 destruction of iron, which at present stands 

 for one half the cost of the sodium produced ; 

 and that it greatly increases the yield of so- 

 dium. The process is equally applicable to 

 potassium. 



Mr. W. H. Harrison, of Sydney, has intro- 

 duced a new process for the reduction of iron- 

 ores. Hydrogen and bicarbureted hydrogen 

 (coal-gas) are injected into the blast-furnace. 

 The hydrogen carries off the impurities, and 

 pure iron is left in the bed of the furnace. 



For zinc-coating objects which, on account 

 of their large size or of their being fixed can 

 not be plunged into the galvanizing bath of 

 melted zinc, Neujean and Delaite, of Lie~ge, 

 recommend painting, in the ordinary manner, 

 with finely powdered zinc, mixed with oil 

 a drier. The process is cheaper than ordim 

 galvanizing and equally durable. 



By Zaboudsky's new method for determii 

 ing carbon in cast-iron, the finely pulverize 

 metal is mingled with a dry mixture of copper 

 and sodium chloride. Water is added, and th< 

 mass is triturated. The whole is then gent" 

 heated with ferric- chloride solution, and h 

 drochloric acid is added. The carbonaceous 

 material should remain undissolved. The resi- 

 due is not pure carbon, but contains hydi 

 and oxygen in combination. 



In a method for testing phosphoric crude 

 iron in open-hearth furnaces, described by J. 

 W. Wailes, the process is similar to the ordi- 

 nary puddling operation, and is conducted in a 

 furnace with a basic lining; the metal is, how- 

 ever, removed from the furnace in a molt( 

 condition. 



A method has been introduced for casting 

 iron or steel on brass. The brass core is cast 



