June 20, 1889] 



NAIURE 



18:? 



For the production of 22,400 j pounds "double chloride is 

 required : — 



Common salt 8,000 pounds 



Alumina hydrate ... ... ... 11,000 ,, 



Chlorine gas 15,000 ,, 



Coal 180 tons. 



For the production of 15,000 pounds of chlorine gas is re- 

 quired : — 



Hydrochloric acid 180,000 pounds 



Limestone dust... ... ... ... 45,000 ,, 



Lime ... ... ... ... ... 30,000 ,, 



Loss of manganese ... ... ... 1,000 ,, 



[These figures were rendered more evident by the aid of 

 small blocks, each cut a given size, so as to represent the rela- 

 tive weights of the different materials used to produce one unit 

 of aluminium.] 



It might seem, on looking over the above numbers, as if an 

 extraordinary amount of waste occurred, and as if the produc- 

 tion is far below that which ought to be obtained, but a study of 

 the figures will show that this is not the case. I would wish to 

 call attention to one item in particular, viz. fuel, it having been 

 remarked that the consumption of coal must prevent cheap pro- 

 duction. I think, when it is remembered that coal, such as is 

 used at the works, costs only /^s. per ton, while the product is 

 worth ;^2240 per ton, the cost of coal is not an item of conse- 

 quence in the cost of production. The total cost of the coal to 

 produce one ton of metal being ^50, the actual cost for fuel is 

 less than 6d. for every pound of aluminium produced. The 

 ratio of cost of fuel to value of product is indeed less than is 

 the case in making either iron or steel. In concluding my re- 

 marks as to the method of manufacture and the process in 

 general, I do not think it is too much to expect, in view of the 

 rapid strides already made, that, in the future, further improve- 

 ments and modifications will enable aluminium to be produced 

 and sold even at a lower price than appears at present possible. 



Properties of Alutninium, 



In its physical properties, aluminium widely differs from all 

 the other metals. Its colour is a beautiful white, with a slight 

 blue tint. The in'ensity of this colour becomes more apparent 

 when the metal has been worked, or when it contains silicon or 

 iron. The surface may be made to take a very high polish, 

 when the blue tint of the metal bee imes manifest, or it may be 

 treated with caustic soda and then nitric acid, which will leave 

 the metal quite white. The extensibility or malleability of 

 aluminium is very high, ranking with gold and silver if the 

 metal be of good quality. It may be beaten out into thin leaf 

 quite as easily as either gold or silver, although it requires more 

 careful annealing. 



It is extremely ductile, and may be easily drawn, especial care 

 only being required in the annealing. 



The excessive sonorousness of aluminium is be.-t shown by 

 example [large suspended bar being struck]. F'araday has 

 remarked, after experiments conducted in his laboratory, that 

 the sound produced by an ingot of aluminium is not simple, 

 and one may distinguish the two sounds by turning the vibrating 

 ingot. 



After being cast, it has about the hardness of pure silver, but 

 may be sensibly hardened by hammering. 



Its tensile strength varies between 12 and 14 tons to the inch 

 [test sample which was shown having been broken at 13 tons or 

 27,000 pounds], ordinary cast iron being about 8 tons. Com- 

 paring the strength of aluminium in relation to its weight, it is 

 equal to steel of 38 tons tensile strength. The specific gravity 

 of cast aluminium is 2-58, but, after rolling or hammering, this 

 figure is increased to about 2 '68. 



The specific gravity of aluminium being I, copper is 3 "6, 

 nickel 3-5, silver 4, lead 4'8, gold 77. 



The fusibility of aluminium has been variously stated as being 

 between that of zinc and silver, or between 600° and lcoo° C. 



As no reliable information has ever been made public on this 

 subject, my friend Prof. Carnelley undertook to determine it. 

 I was aware, from information gained at the works at Oldbury, 

 that a small increase in the percentage of contained iron 

 materially raised its point of fusion, and it has been undoubtedly 

 due to this cause that such wide limits are given for the melting- 

 pomt. Under these circumstances two samples were forwarded 

 for testing, of which No. i, containing \ per cent, of iron, had a 



melting-point of 700° C. No. 2, containing 5 per cent, of iron, 

 does not melt at 700°, and only softens somewhat above that 

 temperature, but undergoes incipient fusion at 730°. 



According to Faraday, aluminium ranks very high among 

 metallic conductors of heat and electricity, and he found that it 

 conducted heat better than either silver or copper. The specific 

 heat is also very high, which accounts for length of time required 

 for an ingot of the metal to either melt or get cold after being 

 cast. 



Chemically, its properties are well worthy of study. 



Air, either wet or dry, has absolutely no effect on aluminium 

 at the ordinary temperature, but this property is only possessed 

 by a very pure quality of metal, and the pure metal in mass 

 undergoes only slight oxidation even at the melting-point of 

 platinum. 



Thin leaf, however, when heated in a current of oxygen, 

 burns with a brilliant, bluish-white light. [Experiment shown.] 

 If the metal be pure, water has no effect on it whatever, even at 

 a red-heat. Sulphur and its compounds also are without action- 

 on it, while, under the same circumstances, nearly all metals 

 would be discoloured with great rapidity. [Experiment shownr 

 using silver and aluminium under the same conditions.] 



Dilute sulphuric acid and nitric acid, both diluted and concen- 

 trated, have no effect on it, although it may be dissolved in either 

 hydrochloric acid or caustic alkali. Heating in an atmosphere 

 of chlorine it burns with a vivid light, producing aluminium 

 chloride. [Experiment shown.] In connection with the subject 

 it may be of interest to state the true melting-point of the double 

 chloride of aluminium and sodium, which has always been given 

 at 170° to 180" C, but which Mr. Baker, the chemist to the 

 works, finds lies between 125' and 130° C. 



Uses of Ahiminitim. 



Its uses, unalloyed, have heretofore been greatly restricted. 

 This is, I believe, alone owing to its former high price, for no 

 metal possessing the properties of aluminium could help coming 

 into larger use if its cost were inoderate. Much has been said 

 as to the impossibility of soldering it being against its popular 

 use, but I believe that this difficulty will now soon be overcome. 

 The following are a few of the purposes to which it is at present 

 put : telescope tubes, marine glasses, eye-glasses and sextants, 

 especially on account of its lightness ; fine wire for the making 

 of lace, embroidery, &c ; leaf in the place of silver leaf, sabre 

 sheaths, sword handles, &c., statuettes and works of art, 

 jewellery and delicate physical apparatus, culinary utensils, 

 harness fittings, metallic parts of soldiers' uniforms, dental 

 purposes, surgical instruments, reflectors (it not being tarnished 

 by the products of combustion), photographic apparatus, aero- 

 nautical and engineering purposes, and especially for the making 

 of alloys. 



Alloys of Aluminium. 



The most important alloys of aluminium are those made with, 

 copper. These alloys were first prepared by Dr. Percy, in 

 England, and now give promise of being largely used. The 

 alloy produced by the addition of 10 per cent, of aluminium to 

 copper, the maximum amount that can be used to produce a 

 satisfactory alloy, is known as aluminium bronze. Bronzes, 

 however, are made which contain smaller amounts of aluminium, 

 possessing in a degree the valuable properties of the 10 per cent, 

 bronze. According to the percentage of aluminium up to 10 

 per cent., the colour varies from red gold to pale yellow. The 

 10 per cent, alloy takes a fine polish, and has the colour of • 

 jeweller's gold. The 5 per cent, alloy is not quite so hard, the 

 colour being very similar to that of pure gold. I am indebted 

 to Prof Roberts Austen for a mould in which the gold at the 

 mint is usually cast, and in this I have had prepared ingots of 

 the 10 and 5 per cent, alloy, so that a comparison may be made 

 of the colour of these with a gold ingot cast in the same mould,, 

 for the loan of wtiich I have to thank Messrs. Johnson, Matthey, 

 and Co., all of which are before you. 



I have also ingots of the same size, of pure aluminium, from 

 which an idea of the relative weights of gold and aluminium 

 may be obtained. 



To arrive at perfection in the making of these alloys, not only 

 is it required that the aluminium used should be of good quality, 

 but also that the copper must be of the very best obtainable.. 

 For this purpose only the best brands of Lake Superior copper 

 shoiddbe used. Inferior brands of copper or any impurities in 

 the alloy give poor results. The alloys all possess a good colour, 

 polish well, keep their colour far better than all other copper 



