D. CHEMISTRY AND METALLURGY. 211 



ed its maximum temperature and maximum capacity. The 

 vessel and its contents, when cold, were again weighed, and 

 there were thus obtained the elements necessary for deter- 

 mining the specific gravity of the cast iron which filled the 

 vessel when in a molten state. The result is that, whereas 

 the specific gravity of cast iron when cold is 7.17, it is when 

 melted only Q.65. Cast iron, therefore, is less dense in the 

 molten than in the solid state. The statements commonly 

 made and believed as to the floating of lumps of solid iron 

 furnace slag upon the melted slag are examined, and reasons 

 are given for believing that even such slags are not denser 

 in the molten than in the solid state, and that the floating 

 referred to is due to other causes. 12 A\ X., 157. 



VOLATILIZATION OF METALLIC IRON. 



According to the journal of the Iron and Steel Institute, 

 Dr. Eisner placed a piece of wrought iron in a closed crucible 

 of unglazed porcelain, and exposed it for several hours to a 

 temperature of 3000 Fahr. in a kiln. On examining the 

 crucible when cold it was found that the iron had been vol- 

 atilized, and condensed on the under surface of the lid in 

 small needle-shaped crystals, thus proving what had been 

 suspected, but which had never been positively known be- 

 fore namely, the possibility of such volatilization. 15 A, 

 August 23, 1873, 244. 



PREPARATION OF ALUMINIUM. 



Garneri, of London, prepares this metal by placing a mixt- 

 ure of 100 parts of alumina, obtained in the usual way from 

 kaoline, etc., with 40 parts of charcoal, heated to redness, in 

 retorts at a dark red heat, and leading chlorine into them 

 from an iron o;asometer lined with lead, and closed with tras- 

 tar covered with hydrochloric acid. The volatilized chloride 

 of aluminium formed is condensed in vessels of sheet iron, 

 glazed internally, and is decomposed by an electrical current 

 produced by a magneto-electric machine. The liberated chlo- 

 rine is returned to the gasometer. 34 C, X., 7G. 



MELTING AN EXTRAORDINARY MASS OF PLATINUM. 



The largest mass of the alloy of platinum and iridium 

 that has ever been melted at one operation was recently 



