Ml.TALLURGY. (ALUMINUM, (ioi.i,, SILVER.) 



platinum ninl its alloys is three times as great. 

 When heated in o\\gi-n. Hi' 1 curve nf eiertnc iv- 

 si-taiice i'. .r sihcr remained straight, it- me 

 ehaiiical |>rn|iri I n - were not changed, anil its 

 melting |'"int us found tube 1.7:!;; ( '. U In n 

 i with hvdingeii its properties were 

 changed from the temperature of l.'-'OO ('.; ils 

 nice increased more rapidly lliaii when in 

 ii. I lie mrtal after cooling showed great 

 :igth, and the melting point was low- 

 ered in l.iiso ('. The metal lakes on a dull ap- 

 106 similar in that of palladium, olttained 

 by deposition from its hydrate. These IV.cts 

 I hat silver at a red heat occludes hydro- 

 gen. A lar-' 1 number of metals show like 

 imii. sudden mnlecular changes, which occur at 

 well-delined temperatures. The electrical re- 

 Mstances then show nt those temperature!? sud- 

 den variations in their law of increase, but the 

 absolute value does not change on passing a 

 pim where those changes occur, as is the < -a-e 

 on passing the melting point. Molecular changes 

 occur in /inc at (ISO ('. ; in brass, with 38 per 

 cent, of /inc. at I .'!:!<" ('.; and with an alloy of 

 cnppcr, iron, and nickel at 1,270 '('. In brass 

 the molecular change is accompanied by a con- 

 siderable absorption of latent heat. Some alloys 

 show progressive molecular changes which call 

 to mind those observable in the chemical equilib- 

 rium of saline solutions. The presence of small 

 quantities of foreign matter seems to hinder the 

 transformation and the amount of the change 

 seems to vary considerably with different speci- 

 mens. At temperatures above those of trans- 

 formation, iron, nickel, and their alloys exhibit 

 a law of change for the electrical resistance 

 which is similar to that of platinum and its al- 

 loys, while at lower temperatures the law of 

 change is infinitely more rapid. 



By means of the acoustic method which he 

 has invented. M. Morcadier finds that steel con- 

 taining nickel in the proportion of 25 to 100 is 

 homogeneous and nearly isotropic. The incorpo- 

 ration of the nickel with the steel in sufficient 

 quantity, he adds, while increasing the homo- 

 geneity of the metal, imparts to it an isotropy 

 similar to that of the Mies glacea of Saint-Go- 

 bain. 



Aluminum. According to a paper by Dr. 

 Lindeck, of Darmstadt, aluminum is preferable 

 to silver on account of its lightness and its non- 

 discolorative quality. It is, however, effected by 

 alkalies and even by soap; it can not, therefore, 

 be used in the manufacture of household utensils. 

 As an adjunct for the production of castings free 

 from blow-holes, for use in the manufacture of 

 the lighter parts of instruments, for the manu- 

 facture of tubes and wires, etc.. it is adapted in 

 a remarkable degree. As an alloy it is also very 

 useful ; and it meets with great favor in the fine 

 arts; but no method of soldering the metal has 

 yet been invented. llrr von Vogtlander. in 

 the discussion of the paper, referred to the difli- 

 eulties experienced in the employment of the 

 metal as a greater drawback to its general use 

 than the question of price. 



Graham's method of obtaining aluminum is 

 based upon the reduction by sodium of fluoride 

 of aluminum, produced by the action of sul- 

 phate of alumina upon fluor-spar and cryolite; 

 but the latter mineral is employed only at the 



beginning of )),,. operation, after whi.h it in re- 

 produced in large quantity in an artilicial fntin. 



as a en|i-e,|lienec nt the reduction of the Illlnllile 



of aluminum. Tim- obtained, it in of higher 

 purity than the natural mineral, which ulways 

 contains spathic iron ore and quart/. 



In the Hall process for preparing aluminum 

 a mixture of alumina and some fluoride serving 

 as a llux is submitted to the action of il. 

 trie current, the elecl rnlyte iH-ing placed in ves- 

 sels of iron lined with coke and havingacapaeitj 

 for from NO to i:;o kilogrammes of material. 

 Km- obtaining pure aluminum the electrodes are 

 made of carbon ; for aluminum bron/e. 

 electrodes are used, which dissolve as the min- 

 eral is reduced. 



Aluminum and its alloys can be smelted in a 

 small way in ordinary lire-clay or iron crucible* 

 without the metal thereby becoming brittle or 

 acquiring silicon, provided no liquid method is 

 employed and the smelting point is not too 

 much exceeded. Large quantities of aluminum 

 are smelted in a reverberatory furnace fed with 

 wood or gas fuel. Owing to its high specific 

 temperature, the metal requires much time for 

 smelting, and likewise for cooling to the correct 

 casting temperature. 



A new aluminum flux, called stephanite, is 

 composed of about 70 per cent, of alumina 

 and emery. While not volatilizable, it gives off in 

 the furnace its metallic gases or vapors, which 

 unite with the fusible iron acting as a condens- 

 ing agent, while all impurities go to the liquid 

 slag and are drawn off in the usual manner. The 

 tests of the action of this flux, made in June, at 

 Messrs. H. Young & Co. *s foundry, Pimlico, gave 

 the "inevitable conclusion " that Mr. Stephen's 

 method of incorporating aluminum with iron is 

 a practical success, producing a metal combining 

 the qualities of iron and steel. 



One of the new applications of aluminum is to 

 the refining of other metals by the addition of 

 small quantities of it. It is thus applied to the 

 refining of iron, copper, and brass. 



(jold and Silver. Balling's method of using 

 cadmium in assaying gold bullion is regarded 

 by Mr. Cabcll \Vhitehead as inferior to the old 

 method with silver: but with certain modifica- 

 tions it may be found rapid and satisfactory for 

 a preliminary assay. The author has found 

 cadmium an efficient aid in the estimation of 

 small quantities of silver in gold bullion con- 

 taining considerable amounts of copper or 

 platinum. In his method the ore is covered with 

 potassium cyanide, and heated till the cyanide 

 is in quiet fusion. A suitable proportion of 

 cadmium is then dropped into the crucible, where 

 it quickly melts and forms a bright, homoge- 

 neous alloy with the gold. On cooling the con- 

 tents on a porcelain slab, the alloy will be found 

 in one piece, and is easily detached from the 

 potassium cyanide. It is then washed in warm 

 water, dried, and placet! in a mortar, where sev- 

 eral sharp blo-,vs with a hammer quickly reduce 

 il in powder, which is assayed. 



The improved furnace of the Fulton Iron 

 Works. San Francisco, for melting bullion is 

 operated on the principle of an ordinary forge. 

 The pan constituting the bottom of the furnace 

 is filled with a mixture of bone ash and fire-clay, 

 thoroughly tamped down and then scooped out, 



