286 ANNUAL OP SCIENTIFIC DISCOVERY. 



alloys with iron are very fusible, and in their physical properties resemble 

 cast iron and steel. A very hard, brittle and white alloy of silicon and cop- 

 per containing twelve per cent, of silicon is prepared by fusing together three 

 parts of fluosilicate of potash, one part of sodium, and one part of copper 

 turnings, till a very liquid scoria is obtained. An alloy of copper and sili- 

 con containing 4'8 per cent, of silicon possesses a beautiful clear bronze color. 

 It is a little less hard than iron, and may be filed, sawed, or turned, like that 

 metal. It is perfectly ductile, and wires drawn from it are as tenacious as 

 those of iron. The hardness of the siliciurets increases with the quantity of 

 silicon, but at the same time their ductility diminishes. They are all char- 

 acterized by the fact that silicon is uniformly distributed throughout the mass 

 so that the alloys are homogeneous and not susceptible of liquation. The 

 authors presented to the Academy two small cannon made of alloys of cop- 

 per and silicon. They furnish examples of what maybe done in the arts by 

 the application of the alkaline metals, and of the progress which is every day 

 making in the manufacture of sodium. The authors have not limited their 

 experiments to silicon, but expect by similar methods to prepare other simple 

 or compound bodies in a crystallized state. Comptes Rendus, xlv, 1 63, 

 Aug. 1857. 



New Oxide of Silicon. "Wohler has communicated to the French Acad- 

 emy of Sciences a brief notice of a new oxide and chlorid of silicon. While 

 occupied with the study of the conducting power of aluminum for the gal- 

 vanic current, Wohler and Buff observed that when a plate of this metal is 

 made the positive pole in a solution of chlorid of sodium, a gas is disengaged 

 which takes fire spontaneously in the air. Supposing that the silicon con- 

 tained in the aluminum had something to do with the phenomenon, the 

 authors sought to prepare the gas by purely chemical means. By heating 

 silicon to redness in a current of dry chlorhydric acid gas the acid was easily 

 decomposed, hydrogen being evolved and a new chlorid of silicon produced. 

 This is a fuming, very mobile liquid, more volatile than the ordinary chlorid, 

 SiCls- It is decomposed by water in chlorhydric acid and a new oxide of 

 silicon. This latter is a white matter, slightly soluble in water, and very 

 soluble in alkali, even in ammonia, disengaging hydrogen gas with efferves- 

 cence, and becoming converted into silicic acid. Heated in the air it takes 

 fire and burns with a very white light, disengaging hydrogen, which takes 

 fire. The authors are studying the constitution of the new chlorid and oxide. 

 Comptes Rendus, xliv, 834. 



ON GOLD IN THE FOR5I OF MALLEABLE SPONGE. 



Mr. D. Forbes recently described to the London Chemical Society the 

 following process for converting gold into the form of a malleable sponge, 

 suitable for employment for dentists in the place of the oi'dinary gold leaf. 



Gold free from copper is dissolved in nitre-hydrochloric acid, keeping an 

 excess of gold in the solution towards the close of the operation, so as to get 

 rid of all nitric acid and avoid subsequent evaporation ; any chloride of 

 silver present is filtered off. The solution of gold is now placed in a flat- 



