462 Sir Henry Boscoe [^^'^7 3, 



chlorine it bnrns ^yith a vivid liglit, producing aluminium cliloride. 

 (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 loO' C. 



Uses of Ahuniniiun. 



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 moderate. Much has been said as to the impossi- 

 bility 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 w^re for the making of hice. embroidery, &c. Leaf in the place 

 of silver leaf, sabre sheaths, sword handles, ike, statuettes and -works 

 of art, jewellery and delicate physical aj^paratus, culinary utensils, 

 harness fittings, metallic parts of solders' uniforms, dental purposes, 

 surgical instruments, reflectors (it not being tarnished by the pro- 

 ducts of combustion), photographic apparatus, aeronautical and 

 engineering purposes, and especially for the making of alloys. 



Alloys of Aluminium. 



The most important alloys of alummium 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 jjercentage 

 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 jewellers' 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. Pioberts Austen for a splendid specimen of crystallised gold, 

 as also 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 which I have to thank 

 Messrs. Johnson, Matthey, & Co., all of which are before you. 



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

 au 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 



