290 ANNUAL OF SCIENTIFIC DISCOVERT. 



coins, whilst at the same time injuring the malleability of the copper. 

 One-tenth of aluminium gives with copper a pale gold-colored alloy of great 

 hardness and malleability, and capable of taking a polish like that of tecl. 

 Tive parts of aluminium with one hundred parts of pure silver give an alloy 

 almost as hard as silver coin containing one tenth of copper, and thus per- 

 miis us to harden silver without introducing a poisonous metal. Comptes 

 Rendus, xliii, 885. 



Debray has also communicated the results of experiments on the alloys 

 of aluminium, apparently more numerous and varied than those of MM. 

 Tissicr. 



According to this authority it forms alloys with most metals, and in most 

 cases the combination takes place with great evolution of light and heat. 

 An alloy of ten parts of aluminium and ninety parts of copper possesses 

 greater hardness than ordinary bronze, and is worked when hot with more 

 ease than the best soft iron. As the proportion of aluminium increases, the 

 alloys generally become harder ; they become brittle beyond very narrow 

 limits with gold and copper. These metals also lose their color, and soon 

 become completely colorless. Aluminium becomes more brilliant and a little 

 harder, still remaining malleable, with small proportions of zinc, tin, gold, 

 silver, and platinum. Iron and copper do not greatly injure the properties 

 of aluminium if they arc not in too great quantities; one or two per cent, 

 of sodium, on the contrary, forms an alloy which readily decomposes cold 

 water. For practical purposes, it is unnecessary that aluminium should be 

 entirely deprived of iron. Metal reduced from impure chlorides, but of 

 which the malleability and tenacity differed but little from those of pure 

 aluminium, contained seven to eight per cent of iron. The union of the IAVO 

 metals takes place with facility ; the iron pokers with which the liquid baths 

 are stirred in the furnaces where aluminium is produced become covered with 

 a brilliant layer of this metal. Aluminium contaminated with iron is puri- 

 fied by a simple fusion in nitrate of potash. M. Debray alloyed five parts 

 of aluminium with ninety-five parts of iron, without imparting to the latter 

 properties very different from its own. An alloy of zinc containing ninety- 

 seven of aluminium and three of zinc is a little harder than die metal ; al- 

 though very malleable, it is equal in brilliancy to any other alloy of alumi- 

 nium. Aluminium may contain ten per cent, of copper without losing its 

 malleability, which is diminished, however; the metal reduced in copper 

 trays contains from five to six per cent. ; it is also worked with facility. 

 With ten per cent, it becomes brittle, but remains white as long as the pro- 

 portion of copper does not exceed 80 per cent. The alloy thus obtained is 

 white and brittle, and resembles the metal of telescope mirrors. The alloy 

 with eighty-five per cent, of copper is still brittle, but begins to grow yellow. 

 The copper probably loses its color when it is below eighty-two per cent., 

 which corresponds with Cu 2 A 1 . The aluminium bronze already mentioned 

 unites with the property of being forged when hot, that of great unalterability 

 in the presence of hydrosulphate of ammonia. Its yellow color is fine, but 

 inferior to that of the alloy of ninety-five copper and five aluminium. An 

 alloy of three parts silver and ninety-seven aluminium has a very fine color, 



