METALLURGY. 



535 



show that steel with 0'50 per cent, of carbon, 

 from 0*40 to 0*50 per cent, manganese, 0*20 

 per cent, phosphorus, and 0*50 per cent, cop- 

 per, does not exhibit red-shortness. 



Aluminum. A description of the Cowles elec- 

 trical furnace for the reduction of aluminum 

 and other metals was given in the "Annual 

 Cyclopedia " for 1885, together with an account 

 of what had been accomplished with it. The 

 inventor of the furnace, Mr. Cowles, in a paper 

 read before the Franklin Institute in January, 

 1886, gave some calculations concerning the 

 workings of his method and its economical 

 aspects, including both what had been realized 

 and what he expected to obtain. The appa- 

 ratus has been employed " for the purpose of 

 experiment in the reduction of refractory ores 

 for the production of metallic calcium, mag- 

 nesium, potassium, sodium, silicon, titanium, 

 and the manufacture of aluminum and alumi- 

 num-bronze and other alloys," and includes 

 two brush dynamos, one of them a very pow- 

 erful machine. It weighs more than 7,000 

 pounds, and at a speed of 907 revolutions per 

 minute produces a current of 15'V5 amperes 

 with an intensity of 46'7 volts. From this en- 

 gine an average daily production of at least 300 

 pounds of 10 per cent, aluminum-bronze for 

 20 hours' work is expected, besides about 60 

 pounds of metallic aluminum in the by-prod- 

 ucts, a large proportion of which may be 

 cheaply reclaimed and made marketable. This 

 total quantity of 90 pounds of the metal in 20 

 hours is equivalent to 4^- pounds an hour ; and 

 this, produced by the energy of 120 horse- 

 power, gives the consumption of about 26'6 

 horse-power per hour, as required to reduce 

 1 pound of aluminum. The 10 per cent, alumi- 

 num-bronze may be sold without financial loss 

 at 45 cents per pound net as against the ordi- 

 nary price of $1.30 per pound. The list price 

 of the product is 60 cents per pound. By the 

 addition of zinc to the lower grades of alu- 

 minum-bronze an aluminum-brass is produced 

 which is at once tough and malleable, and of 

 greater tensile strength than ordinary brass. 

 It has also superior power to resist corrosion 

 and oxidation, and can be made from the alu- 

 minum-bronze at a cost of 18 or 20 cents a 

 pound. The inventor claims that he can 

 charge iron, manganese, tin, copper, nickel, 

 etc., with a very high percentage of metallic 

 aluminum, and that also, without any base 

 metal in the furnace, he can saturate the char- 

 coal contained therein with metallic aluminum, 

 most of which will be in a state of mechanical 

 mixture with the carbon ; and, further, that spe- 

 cimens of aluminum, 99 per cent, pure, have 

 been produced in at least three different meth- 

 ods by the electric furnace. Prof. C. B. Ma- 

 bery related to the American Association that 

 in his later experiments the inventor had found 

 that the efficiency of the charcoal could be in- 

 creased, and the formation of graphite pre- 

 vented in part by coating the charcoal, pre- 

 vious to using it, with lime. The quantity of 



product was increased when the electrodes 

 were allowed to enter the mixture of ore and 

 carbon, at an angle of about 30 from the hori- 

 zontal plane. A continuous reduction is more 

 easily effected when the electrodes are capable 

 of being drawn apart so as gradually to expose 

 fresh portions of ore to the action of the cur- 

 rent. By an adaptation of the furnace for the 

 reception of very powerful currents, the energy 

 from 300 horse-power may be utilized, instead 

 of that from 30 horse-power, which was for- 

 merly employed. An assertion which had 

 been made by Dr. Siemens, that aluminum 

 could not be reduced without ccpper, was pro- 

 nounced erroneous. Mixtures of metallic alu- 

 minum and carbon had been repeatedly taken 

 from the furnace in large quantities. By re- 

 ducing aluminum in presence of iron, a cast- 

 iron is formed, sometimes containing as much 

 as 10 per cent, of aluminum, and this product is 

 used to facilitate the working of crude iron and 

 to introduce into the various grades a small per- 

 centage of aluminum. The slags resulting from 

 this reduction are composed chiefly of calcic 

 aluminate and cast-iron. In the reduction of 

 aluminum in the presence of copper a yellow 

 product is frequently taken from the furnace 

 which is composed of metallic aluminum to the 

 extent of one half or three fourths, the rest 

 being silicon and copper. "With a small per- 

 centage of calcium it is also formed in the ab- 

 sence of copper, and then contains a higher per- 

 centage of aluminum and often nitrogen. It has 

 a resinous luster, and decomposes water at 100 

 0. The aluminum slags are composed of re- 

 duced metal, calcic aluminate, and fused oxide, 

 and a carbide of aluminum may also be pres- 

 ent. A bar of 10 per cent, bronze which had 

 been heated for the purpose of forging, was al- 

 lowed to become too hot, and when struck the 

 entire bar assumed a crystalline condition. 

 Some of the individual crystals were nearly 

 perfect in form, resembling some of the forms 

 of the isometric system. In the reduction of 

 silicon the formation of a greenish-yellow sub- 

 stance is frequently observed, and it has proved 

 by analysis to be a new oxide of silicon SiO. 

 By fusion with fluxes it is converted into the 

 dioxide, and hydrofluoric acid acts upon it the 

 same as upon the dioxide. Large works for 

 the production of aluminum are in course of 

 erection at Hamelin, near Bremen, at which 

 the Graetzel process, consisting in passing a 

 powerful electric current through a bath of 

 molten sodium aluminum chloride, is to be em- 

 ployed. 



Mr. J. W. Mallet, having prepared and exam- 

 ined a specimen of pure aluminum, has found 

 its color to be perceptibly whiter than that of 

 the commercial metal, it being on a cut surface 

 very nearly tin-white. The luster is also very 

 much like that of fresh, untarnished tin. The 

 metal was distinctly softer than before purifi- 

 cation. Hence its fracture was not easily ob- 

 served, but it seemed to be very fine-grained, 

 with some appearance of fibrous silkiness. The 



