264 



SCIENCE. 



[Vol. XIII. No. 322 



openings, covered by movable, brick-lined plates, or doors, through 

 which the crucibles can be got at. The flame playing over the 

 hearth is conveyed by a short flue, fitted with a damper, to the 

 chimney. Under the hearth is another flue communicating with 

 the furnace, and also leading to the chimney, and fitted with a 

 damper. By manipulating the two dampers, the flame may be 

 directed either under or over the hearth at pleasure. The furnace 

 proper is at the end of the hearth farthest from the chimney, and 

 consists of a peculiarly constructed apparatus, whereby the cheap 

 residues resulting from the distillation of kerosene, or the heavy 

 oils obtained from gas-works, can be burned with the ordinary 

 chimney-draught, and a most intense heat produced. The pair of 

 crucibles next the furnace are the most highly heated. The metal 

 in them melts first, and, as soon as the crucibles are removed for 

 pouring, the remaining four are moved up near the flame, and two 

 freshly charged ones put in at the end nearest the chimney, by which 

 means most of the heat produced by the combustion of the fuel is 

 utilized. As soon as the iron is fairly melted, but not overheated, 

 aluminium is added, when the charge instantly becomes quite fluid, 

 and fit for pouring, the lowering of the melting-point having had 

 the same effect as superheating the metal. 



The mitis castings possess all the properties of the best forged 

 iron, the tensile strength ranging as high as 27 tons per square 

 inch, with an elongation of 20 per cent. The metal can be worked 

 and welded just like wrought iron, and in fact cannot be distin- 

 guished from it, except that it is perfectly homogeneous and free 

 from stratification. 



When aluminium is used in such small quantities, it is best to 

 make a preliminary rich alloy with iron (say, one containing from 

 10 per cent to 25 per cent of aluminium), and then to add so much 

 of the alloy to the charge in the crucibles as will give the desired 

 proportion of the more costly metal. This is the more necessary 

 on account of the extreme lightness of aluminium, which makes it 

 reluctant to mix with a metal three times its specific weight. 



Aluminium alloys readily with copper in all proportions, and 

 constitutes the metal known as aluminium bronze. The usual pro- 

 portion ranges from 2^ to 10 per cent of aluminium ; and it is 

 probable that the bronzes resulting form true alloys or solutions, 

 because the addition of the lighter metal causes a marked increase 

 of temperature of the molten mass, indicating the existence of 

 chemical re-action ; and the bronzes may be melted frequently 

 without changing the relative proportion of the constituent metals. 

 The tenacity and rigidity of the copper are much enhanced ; 10- 

 per-cent alloys having sustained as much as 45 tons per square 

 inch, with an ultimate extension of 25 per cent. It must be remem- 

 bered, however, that, to obtain the best results, absolute purity, or, 

 at any rate, fixity of composition, both in the copper and aluminium, 

 must be insured. Failing that, very discordant and disappointing 

 results will be arrived at. The aluminium alloys of copper, up to 

 10 per cent, can be forged, and rolled hot, and worked as readily as 

 ■copper, proper precautions with respect to annealing being ob- 

 served. The color of the aluminium bronzes approaches very 

 nearly that of gold. The metal takes a high polish, and is less 

 liable to tarnish than ordinary bronzes or than copper itself. 



Aluminium forms alloys with most other metals ; but they pos- 

 sess no practical value at present, and therefore need not be de- 

 scribed. 



A discussion followed, in which Mr. E. Riley said he had gone 

 into this question many years ago, when Sir Lowthian Bell brought 

 ■out his process, and he had some experience of the so-called alloys 

 of aluminium, having had numerous samples submitted to him. 

 He wished to ask whether the Aluminium Company had any pro- 

 cess by which the aluminium could be got from clay. With regard 

 ■to the result of the alloys, he thought that practically the alloy of 

 copper had proved very satisfactory, but, when they came to ana- 

 lyze it, no aluminium was found, except, perhaps, a mere trace. 

 Some mitis castings were submitted to him a few years ago by Mr. 

 Nordenfeldt, but he found no aluminium in them ; and so it was in 

 the so-called alloys. He had also had several samples from Amer- 

 ica. There was nothing more easy to find than aluminium, but it 

 might be there were several things which could be confounded with 

 it. As regarded the action of aluminium on metals, his view was 

 that it took away the oxygen, and made the casting more solid. It 



was important to the Aluminium Company to know whether any of 

 the processes put forward really reduced alumina or not. It was 

 not an easy matter to find small quantities of aluminium. He had 

 had samples submitted to him which were said to contain 2j per 

 cent, but he could only find a small trace. He believed that alu- 

 minium would be a very valuable adjunct in making steel castings, 

 and it was now being used. He had seen samples of cast iron in 

 which it had been used, and found the castings exceedingly good, 

 besides showing a considerable amount of strength. 



Mr. Jeans bore testimony to the admirable way in which the com- 

 pany's works were conducted, and considered they reflected great 

 credit on the inventor. There was only one other system which 

 had all at once been brought so near perfection by its inventor ; 

 viz., the Bessemer process. Having come into contact with people 

 who were likely to use the metal, he thought the general impres- 

 sion was that it would prove a valuable adjunct to the various 

 forms in which iron and steel were manufactured. It was said that 

 it would be an important element in the production of steel cast- 

 ings ; but he was afraid, from the limited quantity of steel castings 

 produced in England, that it would not be largely used for that 

 purpose for some time to come, though in the production of mitis 

 castings and the like it might be employed on a larger scale. Tak- 

 ing the production of pig-iron in the United Kingdom as about 

 7,500,000 tons a year, he should be disposed to say that rather 

 more than 2,000,000 tons were employed in the production of 

 Bessemer steel, 1,000,000 tons in the Siemens process, and 2,000,- 

 000 tons in the production of manufactured iron, leaving rather 

 over 2,000,000 tons for castings and other purposes. The technical 

 literature of this country, the Continent, and the United States for 

 some time past, had teemed with references to the subject ; and 

 experiments had been made on a large scale, which indicated, that, 

 for castings of every description, this metal was especially valuable. 

 For some time it had been a disputed point how far aluminium was 

 an important element in the production of steel. Professor Fara- 

 day undertook researches into the subject in connection with Wootz 

 steel ; but his conclusions were disputed by eminent chemists, who 

 went over the same ground ; and, if his memory served him accu- 

 rately, Faraday considered the good properties of Wootz steel due 

 to the fact that there was a small percentage of aluminium in it. 

 There could be no question, from what they had seen that night, 

 that there was a great future for the new metal in connection with 

 the metallurgy of iron and steel ; and the effect of the paper would 

 be to throw a new light on the subject, and to inform the outside 

 public of a matter which was of high scientific and commercial im- 

 portance. He thought the time would come when those who used 

 aluminium for alloying purposes would prefer to have a metal in 

 the purest condition in which it could be produced, in order that 

 they might infuse into the casting such a proportion of aluminium 

 as they might deem to be essential for certain specific purposes. 

 In that way the field in the future would belong to the process 

 which could produce the purest aluminium. 



Mr. Alexander Siemens was afraid he occupied the rather invidi- 

 ous position of finding fault with this very excellent process, which 

 gave plenty of opportunities of allowing impurities to get into the 

 aluminium. This fact was admitted in the paper. He had been 

 asked by the inventor of a rival process to describe it, which 

 might be done in a very few words. Mr. Grabau produced a flu- 

 oride of aluminium by certain means, and it was heated until it 

 began to evaporate. When this temperature was attained, a suit- 

 able quantity of sodium was melted and poured into the vessel, 

 which was lined with cryolite and cooled by water ; and the heated 

 fluoride of aluminium, in the form of powder, was thrown upon the 

 melted sodium. Very violent re-action took place, and the heat 

 generated by the re-action was great enough to melt the aluminium 

 as well as the by-product. As soon as the re-action was complete, 

 the whole molten mass could be poured out in suitable forms ; the 

 aluminium settled at the bottom, and the cryolite at the top. To 

 obtain the fluoride of aluminium, Mr. Grabau used the cryolite, which 

 he procured by the final re-action by putting the powdered cryo- 

 lite into a solution of sulphate of aluminium. The re-action which 

 took place between the sulphate of aluminium and the cryolite gave 

 the aluminium fluoride. The solution was afterwards evaporated, 

 and the residue was washed with water, which took out the sul- 



