A/with/am mud fdher the exception of lead. antimony. and mercury. num unites readily with all metals, and many useful alloys of allinlin11111 with other metals have been diseoyered within the lust few years. The oseful alloys of aluminum so far dis eovered are all in Iwo groups, the one of alut ll i ll Inn with not more than 1:i per cent of other metals, and the other of metals eontaining not over 1:i ffour cent of aluminum; in the one case, the metals imparting hardness and other user!!l qualities to the aluminum, and in the other the aluminum giving useful qmdities to the alloying metals. The addition of a few per cent of silver to aluminum, to harden, whiten, and strengthen the metal, gives an alloy espe cially adaptable for many fine instruments, tools, and electrical apparatus, where the work upon the tool and its convenience are of more consequence than the increased price due to the addition of the silver. The silver lowers the melting-point of the aluminum, and gives a metal susceptible of taking a good polish and making fine castings. Titanium and chromium can be readily alloyed with aluminum, according to the methods devised and patented by Prof. John W. Langley, and will probably prove to be the most valuable means of hardening alumi num. A few per cent of titanium renders the metal, under work, very rigid and yet elastic at the same time. Chromium is the best element to harden aluminum in castings. More or less useful alloys have been made of aluminum with zinc, bismuth, nickel, cadmium, mag nesium, manganese, and tin. these alloys all being harder than pure aluminum; but it is by combination of these metals, with perhaps additions of copper, lead, and antimony, that alloys of most value have so far been discovered. Some are with additions of only 1 to 2 per cent of aluminum. The additions of from 5 to 15 per cent of aluminum to type-metal com posed of 20 per cent antimony and 80 per cent lead makes a metal giving sharper castings and a much more durable type. To ordinary brass the addition of aluminum, especially in the form of aluminized zinc, an alloy of zinc with a few per cent of aluminum, gives superior strength and better anti-corrosive characteristics. Some very marked and valuable qualities have been discovered in the use of aluminum with zinc for various purposes. Additions of from + to 2 per cent of aluminum to Babbitt metal of a composition of copper 3.7 per cent, antimony per cent, tin 89 per cent. gives a very superior bearing metal.
Jlethods of AluminUM 3/(////lfaCtUre.—Alittninum can not be reduced from its oxide by the aid of carbon as a reducing agent. by any of the ordinary methods. because the temperature to which the intimate mixture of the solid carbon and the alumina has to he raised can only be attained by the highest heat of an open-hearth furnace or. in the electrical furnace—a tem perature at which the alumina reduced can not itself be accumulated into a molten liquid mass, and can only he retained by collecting it With a more stahle metal, such as iron or cop per. None of the other salts is susceptible of being reduced by carbon at much lower tempera tures than the oxide, so far as yet discovered. The task of producing aluminum at a low cost Inas thus been found to be a difficult one, and many unsuccessful attempts have been made and much money has been lost upon it. Debarred front using carbon as the reducing agent under the ordinary conditions which make it the practicable and economical reagent in most metallurgical operations, the advantages of other stronger reducing agents have been care fully tried. So far only one has proved commercially available, although there are other agents capable of reducing the metal from its salts. Metallic sodium reduces the metal from its chloride or from its fluoride salts readily at a rell-heat. Methods based upon the use of sodium as the reducing agent, have until lately given not only the purest but the cheapest aluminum. These inethods, however. of late have been superseded Iry the cheaper and more direct processes of electrolysis of some of the aluminum salts or of the pure oxide.
History of Manufacture.—Dary. after sneceeiling in isolating metals of t he alkaline earths, tried in vain to separate aluminum from its oxide, alumina. In 1826 Oerstedt formed alumi num chloride by chlorine over a mixture of alumina and charcoal heated to redness in a porcelain tube, hut tried in vain to decompose this salt with sodium or potassium. In 1827 Milder, by better precautions to prevent oxidation, succeeded by the aid of potassium in reducing aluminum from the chloride in the form of a fine. gray powder. It was very im pure, and was only it metallic curiosity. In 1845 Willer obtained the metal in good-sized globules. Deville. twenty-seven years after the first isolation of the metal, in 18:54. was the first to produce the metal in any quantity or with any degree of purity. It is curious to note that the first pure ahunimun made was by electrolysis; both Bunsen and Deville reduced the double chloride of aluminum and sodium by electricity generated by galvanic batteries. Even then the idea of using electricity was old, for Sir Ilumphry Davy, in 1810, publicly described the successful experiment made in 1807. in which he connected the negative pole of a battery of 1,000 double plates with an iron wire which he heated to a white heat and then fused in contact with moistened alumina, the operation hieing performed in an atmosphere of hydrogen. The iron, upon analysis, NV:u found to be alloyed with aluminum. Le Chatelier obtained English patent No. 1.214 in 1861, and Monckton, in 1562. English patent No. 264, for the reduction of aluminum by the aid of electricity. The 31onekton patent proposes to pass all electric eurrent through a reduction-chamber, and in this way to raise the tempera ture to such a point that alumina, will be reduced by the carbon present, this evidently being the incipient idea of the electric furnaee. Gaudin in 1869. Kagensbusch in 1872, Berthaut in 1879, and GrIitzel in 1883 each brought. out processes for producing aluminum by the aid of electricity. The newer pure aluminum processes using electricity, of Hall, Heroult, and the Bernard Brothers, with the help of Minet, together with the alloy processes of Cowles and Heroult. are the only ones now being worked upon a commercial scale. About 1857 the famous works at Salindres was established. under the proprietorship of Peehiney & Co., and this establishment, until within the past three years, produced a larger amount of aluminum than any other in the world. The care and skill shown and the ingenious devices and precau tions taken by the firm to prevent impurities in the metal in the cumbersome and expensive sodium process in which there were so many opportunities for their addition, were worthy of the highest praise. in 1860 Sir I. Lowthian Bell started to manufacture aluminum at NeW eastle-ou-Tyne : the undertaking was abandoned in 1874; the sodium process was used. From
1874 until .1882 the French company at Salindres was the only concern making pure aluniinu in. In 1882 'Webster organized the "Aluminum Crown Metal Company " at Hollywood, near Birmingham, England. and by cheapening the production of aluminum chloride soon devel oped a successful concern. This was further strengthened by the improvement of 11. V. Cast an American chemist, who in 1886 patented improvements for producing a more inti mate mixture of the carbon with the caustic soda in a state of fusion by means of carbide of iron, in this way cheapening by more than one half the cost of manufacture of metallic sodium. This concern was organized under the name of the Aluminium Company, Limited, and put up a large and expensive plant at Oldbury, near Birmingham, England. These works were started at the end of June, 1888, and continued manufacturing until 1890. In common with other manufactures by the sodium process, they have been working to „rent disadvan tage since the advent of the more successful electrolytic processes, and in l891 ceased Opera tions in the manufacture of alutninum. Early in 1888 the Alliance Aluminum Company started a works at Wallsend-on-Tyne, England, using a process: which was an innovation upon the Devine sodium process, and employing the fluoride or the double fluoride of alumi num and sodium cryolite as the compound to be reduced instead of the chloride or the double chloride of the metal. Prof. Netto, the managing director of the concern, also has a process for producing metallic sodium cheaply, by allowing fused caustic soda to trickle over incandes cent charcoal in a vertical retort. Some very excellent aluminum was produced at this works. The Hall process consists in electrolyzing almnina dissolved in a fused mixture of fluor ides of aluminum and sodium, or, in fact, as Mr. flail has described in his letters patent. No. 400,766 a fused bath in which the alumina is dissolved in the fluorides of aluminum, together with the fluoride of any octal more electropositive than aluminum. A volt-meter is attached to each pot, showing increased resistance when the ore gets out of the solvent by electrolysis, and at this time the pot-tender stirs in more ore. The feeding is thus easily made continu ous, and as the fluoride solvent remains constant it only requires tapping the metal ofT—or, as is rather crudely but very satisfactorily done, dipping the metal out in cast-iron ladles, skimming the electrolyte back into the pots with carbon rods—to make the entire opera tion continuous. The cost price for the manufacture of aluminum by direct electrolysis has been brought down very low as compared with the cost of the more complicated processes of a few years ago. the items being: Two lbs, of alumina, containing per cent alumi num. One lb. of carbon electrodes. A small expenditure for its proportionate share of the fluoride salts used for dissolving the alumina. Carbon dust, carbon pot-linings, and the metal pots. About twenty electric horse-power exerted per hour per lb. of 'octal made. Labor and superintendence, general expenses, interest, and repairs. As the Pittsburg Reduction Company uses the process, it places the mixture of fluoride salts, either in a solid condi tion or fused by the aid of external heat, in a row of carbon-lined wrought-iron tanks placed in series. The pots, together with their carbon linings and the reduced metal in the bottom of the pots, become the negative electrodes or cathodes. The positive electrodes or anodes are a series of carbon cylinders, 3 in. in diameter, attached by copper rods to the cop per conductors by the aid of suitable binding screw clamps. A current of large volume is turned on and the mixture, if solid, is incited by the electrically produced heat, when. in less than two hours time, the mixture becomes fluid, and alumina is added. The elec trolyte then becomes a much better conductor, " the resistance of the pot" goes down to a normal one of about eight volts, and the operation of electrolysis commences. The alumina in solution is decomposed; the meta-1, being heavier than the electrolyte, sinks to the bottom of the pot, and the oxygen goes to the positive electrode, uniting with a portion of the carbon and escaping as carbonic-acid gas. The Hall process can be successfully carried on entirely independent of carbon, using a thick iron or copper tank and either iron or copper electrodes. The deposition of the metal is nearly as large as with the use of carbon electrodes; but it is, of course, alloyed with copper or iron from the metal worn away from the positive electrode. The process called the "Minet process," as developed and used at the works of the Ber nard Brothers ;it Creil, Oise, France, consists in electrolyzing a mixture of sodium chloride with the double fluoride of sodium and aluminum, their English patent dating July 18, 1887, No. 10057. This company has been doing successful work, and is now putting aluminum of good quality on the market,. In both the Cowles and Heroult processes nhuninni» is manu factured only in the form of an alloy. The principle involved is the interruption of a power ful electric current. and the formation of an fiffillense are, and the reduction, at the high temperature produced by this arc, of alumina by carbon in the presence of either molten copper or iron. The Cowles furimee is a horizontal box, carbon-lined. having the current carried to it through two ti. in round carbon cylinders, Whieh are arranged so that they may move forward and back in the furnace, which is tilled with broken pieces of carbon and alumina mixed with the carbon and with turnings of iron or copper. The whole of the interior of the furnace is raised to a very high temperature. by the electric arc formed. and the alumina pre ent is reduced by the carbon and alloys with the metal. In the ilerellh process the electrodes are vertical instead of horizontal. lime alumina is fused by the electric are, and, floating- on molten copper or iron, is then treated as though it were 4111 electrolyte ; the carbon rod dipping into the molten alumina being the positive pile. and the molten iron or copper the negative electrode, which is in contact. with the negative pole of tho conduct or. It is probable that there is considerable eleetrolytic action upon the molten alumina in the ileroult furnnee for the roduetion of aluminum, as well as a direct reduction of the oxide by the carbon, The Aluminium Industrie Actien Gesellschaft, at Falls of the Rhine. Nen hausen, in Switzerland. claim to produce from 23 to 30 grammes of aluminum per horse power per liour, in the form of a 10-per-cen1 aluminum-copper bronze.
Aluminium Bronze: see Alloys. Aluminium in Steel: see Steel Manufacture.
Amalgamator: see Mills, Gold. and Mills, Silver.
Ambulance : see Carriages and Wagons.
Ammonia Machine: see lee-making Machine.