CHEMICAL SCIENCE. 289 



jf sodium, one hundred parts ; fluoride of calcium, fifty parts ; sodium, 

 twenty parts. (These proportions may, however, be somewhat varied, ac- 

 cording to circumstances.) These substances having been mixed together, 

 are introduced upon the bed of the furnace, previously heated to redness. 

 The fire bars having been well fed with fuel, the furnace is closed. The 

 reaction will then take place, and by agitating the materials all the alumin- 

 ium will be collected in a mass at the inclined part of the bed, and may bo 

 run off therefrom. By first pouring off the whitest and most fluid portion 

 of the scorias, composed chiefly of the marine salt which has been produced 

 : by the reaction, the fluoride of aluminium (which is also an accessory pro- 

 duct of the reaction) may also be extracted therefrom. The appearance of 

 the scorias remaining- is very peculiar, after cooling ; it is slightly tinged 

 with a color approaching a yellowish gray. This scoriae does not contain 

 the finely-divided aluminium powder which is met with when the reaction is 

 produced with marine salt ; it only contains sometimes globules of alumin- 

 ium, in sufficient quantity to enable it to be collected by pulverizing and 

 washing the mass. When, on the contrary, marine salt is employed, the 

 mass of scorias is of a decided deep gray color ; this arises from the alumin- 

 ium powder mixed with the mass, in which are found only microscopic 

 globules, which are at first difficult to collect, and unite by melting. 



An additional method of producing aluminium has also been recently 

 brought out in England. It consists in placing fluoride of aluminum in an 

 iron oven, which may bo heated in various ways. This oven is first strongly 

 heated, and on the floor thereof is placed a number of shallow dishes. A 

 number of these dishes arc filled with dry and well-powdered fluoride of 

 aluminum, and the remainder with iron filings. They are so arranged that 

 all of those dishes which contain the fluoride arc on all sides surrounded by 

 dishes containing the iron filings. The oven is then closed and luted, and 

 the heat increased to redness, after which a stream of dry hydrogen gas is 



v / O O 



introduced. The effect produced is, that the hydrogen gas combines with 

 the fluorine, and forms hydrofluoric acid, which acid is taken up by the iron, 

 and is thereby converted into fluoride of iron, whilst the resulting aluminum 

 remains in the metallic state in the bottom of the trays containing the 

 fluoride. 



ALLOYS OF ALUMINIUM. 



MM. C. and A. Tissier find that the valuable properties of aluminium are 

 injured by the presence even of small quantities of other metals. One- 

 twentieth of iron or copper make it almost impossible to work the alloy, 

 while one-tenth part of copper renders aluminium as brittle as glass. An 

 alloy of five parts of silver with one hundred of aluminium works like silver, 

 but is harder, and takes a finer polish. The one-thousandth of bismuth ren- 

 ders aluminium so brittle that it cracks under the hammer, even after being 

 repeatedly annealed. The presence of aluminium in other metals often com- 

 municates valuable properties when the quantity is not too large. Thus 

 one twentieth part of aluminium gives copper a 1 en utif.il gold color 

 and hardness enough to scratch the standard alloy ot cold employed for 



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