500 Sir W. Roberts-Austen [Feb. 22, 



temperatures. This question of the transference of oxygen from one 

 metal to another, which results in the liberation of the metal attacked, 

 is of special interest to us at the Royal Institution, for it undoubtedly 

 originated within these walls, and is due to Sir Humphry Davy. He 

 discovered potassium in 1807, and in 1809 attempted to remove the 

 oxygen from alumina by heating it with metallic potassium. He 

 says,* " if I had succeeded in isolating the metal I should have called 

 it ((Illinium." His success was imperfect, but he certainly did 

 obtain, by the intervention of metallic potassium, an alloy of aluininium 

 and iron. It remained for Wohler to prepare pure metallic aluminium 

 from its chloride in 1827, and for Henri Saint Claire Deville, who 

 began to work in 1854, to establish the metallurgy of aluminium on 

 an industrial scale. As regards the reduction of metals from their 

 chlorides, Wohler + obtained crystalline compounds of chromium and 

 aluminium, and Michel | compounds of aluminium with manganese, 

 iron, nickel, tungsten, molybdenum and titanium. Levy § obtained 

 an alloy of titanium and aluminium, Beketoff || an alloy of barium 

 with aluminium from the chloride of barium mixed with baryta. 

 Dr. Goldschmidt % has given references to these authorities in a 

 recent valuable paper. In 1856, Charles and Alexandre Tissier ** 

 observed the fact which is the starting-point of the experiments I 

 have to show you. They found that aluminium decomposes the 

 oxides of lead and of copper, much heat being evolved by the reaction. 

 They do not appear to have used aluminium in a finely divided 

 state, and therefore failed to reduce certain metals from their oxides 

 which are now known to be perfectly easy to reduce. It was not 

 until comparatively recently that the use of aluminium for separating 

 other metals from their oxides assumed serious proportions. Claude 

 Vautin showed on June 13, 1894, at a soiree of the Eoyal Society, a 

 few metals, and among them carbon-free chromium and manganese, 

 Avhich he had prepared, and as he undoubtedly gave the impulse that 

 started much of the subsequent work in this direction, it may be well 

 to give the description which was appended to the specimens he 

 showed. It runs as follows : — 



Specimens of Metallic Chromium, Manganese, Tungsten, Iron, etc. free 

 from Carbon ; also fused Alumina, obtained during the reduction of 

 the metallic samples. 



" The specimens of metallic chromium, manganese, etc. have been 

 reduced from their oxides by means of metallic aluminium. The 



* Phil. Trans, part i. 1810, p. 60. 



t Ann. der Chemie, vol. cvi. p. 118. 



X Ibid. vol. cxv. p. 102; ibid. vol. cxiii. p. 248. 



§ Comptes rendus, vol. cvi. p. (16. 



|| Ann. der Chemie, vol. ex. p. 374. 



i| Ibid. vol. ccci. p. 19. 



** Comptes rendus, vol. xliii. 1856, p. 1187. 



