CHEMICAL SCIENCE. 287 



bottomed vessel and heated, and a strong solution of oxalic acid added ; in 

 a few hours the whole gold is deposited, and the supernatant liquid may be 

 decanted off, taking care all the time not to disturb the gold at the bottom, 

 and the vessel is then several times filled up with boiling water and decanted 

 until the last Avashings contain no more oxalic acid. 



The gold is now carefully slipped on to a piece of filtering-paper, and by 

 means of a spatula gently pressed into the form of the desired cake, but 

 somewhat thicker; it is then removed to a porcelain crucible, and heated 

 for a short time somewhat below a red heat, when it shrinks in dimensions, 

 becomes coherent, and suitable for use. This process is essentially different 

 from one patented and used in this country. 



MANUFACTURE OF ALUMINIUM. 



Dumas recently announced to the French Academy that the problem of 

 rendering the preparation of aluminium an industrial operation has now been, 

 solved. The methods have been devised by MM. Deville and Morin, and 

 differ but little from those originally employed. It is necessary always to 

 decompose the chlorid of aluminium, and decompose it by sodium, in order 

 to obtain the aluminium. The chlorid is now made by the direct use of 

 kaolin, or even of clay. But this is not all. The chloride was difficult to 

 manage in a large way, because, after having been formed in vapor, it was 

 often condensed in snowy crystals, rendering it necessary to collect it in 

 chambers, and detach it mechanically from the surfaces it coated. There 

 was, Jirst, a lo.-s of the chlorid, the condensation being incomplete ; second, 

 danger for the workmen exposed to the respiration of the vapors ; third, 

 an enhancement of cost from the interruptions of the occupations. The im- 

 provement consists in submitting to a current of chlorine no longer a mix- 

 ture of alumina and charcoal, but a mixture of alumina, charcoal and 

 chlorid of sodium ; this affords a double chlorid of aluminium and sodium, 

 which is volatile and liquifiable, running like Avater, and becoming solid with 

 cold. The preparation goes on uninterruptedly, proceeding with simplicity 

 and regularity, and exacting no other care than what is necessary for the 

 production of the chlorid, the renewal of the preparation for decomposition, 

 and the substitution, as soon as cooled, of earthen pots, in which cakes form 

 from the double chlorid that flows in in a continued stream. 



The chlorid is decomposed in a rcverberatory furnace, into which, mixed 

 with bits of sodium, it is introduced. The reaction of the two substances 

 takes place after a few moments, but so quietly that it may be done on a 

 large scale without danger. It leaves the aluminium in plates, globules, or 

 a powder. It is separated from the common salt either mechanically or by 

 means of water. 



Dumas asserts that the cost of making sodium is at the most seven francs 

 a kilogram, and that its manufacture is easier than that of phosphorus and 

 also as simple as that of zinc. 



By acting on a mixture of carbonate of soda, carbon and chalk, the 

 reaction is so complete that the result agrees with calculation, and so easy 

 that we may substitute for the iron bottle commonly used, luted copper 

 tube?. 



