Chemistry and Physics. 47 1 



can be obtained ; showing that these two elements combine 

 readily in a fused medium at ] 200° to 1400°. This compound 

 can be produced much more easily however by heating a mix- 

 ture of 12 parts of carbon and 28 parts of silicon in the electric 

 furnace, the resulting product being treated first with a mixture 

 of nitric and hydrofluoric acids and then with one of nitric acid 

 and potassium chlorate. Generally the crystals are yellow ; but 

 when the operation is conducted with silicon as free as possible 

 from iron, in a closed crucible, the crystals are transparent and 

 sapphire blue in color. Carbon silicide has the composition CSi, 

 has a density of 3 '12, and acts strongly on polarized light. The 

 crystals are very hard and scratch chrome steel and rubies. The 

 silicide is not affected by oxygen or by sulphur vapor at 1000°, 

 though chlorine decomposes it at 1200°. Fused niter, or potas- 

 sium chlorate, boiling sulphuric, nitric or hydrochloric acids, 

 aqua regia and even mixtures of nitric and hydrofluoric acids do 

 not attack it. It is gradually converted by fused potassium 

 hydroxide into potassium carbonate and silicate. 



The latest form of Moissan's electric furnace consists of a rec- 

 tangular block of Courson limestone, containing a large rectangu- 

 lar cavity, lined with alternating plates of magnesia and carbon 

 about a centimeter thick, the magnesia being in contact with the 

 limestone and the carbon lining the interior of the cavity. A 

 lid, also of alternating plates of magnesia and carbon covers the 

 cavity, a block of the same limestone resting upon the lid. The 

 electrodes, which are both movable, pass through slots cut in 

 opposite sides of the furnace. A carbon tube one or two centi- 

 meters in diameter passes through the furnace at right angles to 

 the electrodes being so arranged as to be a centimeter below the 

 arc and the same distance above the bottom of the cavity. 

 When this tube is inclined at an angle of about 30°, the furnace 

 may be made to work continuously, the reducible material being 

 introduced at the upper end and the product of reduction being- 

 drawn off at the lower. With a current of 600 amperes and 60 

 volts, two kilograms of fused metallic chromium can be ob- 

 tained in about an hour, the metals being received in a crucible 

 made of chromic oxide. The metal is white and very hard, is 

 finely granular and takes a high polish. In this furnace both 

 silicon carbide and vanadium carbide can be easily obtained by 

 directly combining the vapors of silicon and vanadium with the 

 vapor of carbon. The plates of magnesia are prepared by heating 

 the basic carbonate, digesting with ammonium carbonate, again 

 strongly heating and then compressing into blocks. — C. H., cxvii, 

 423, 425, 679, Sept., Nov. 1893. G. f. b. 



5. On Crystallized Silicon carbide or Carborundum. — Experi- 

 ments somewhat analogous to those of Moissan have been made 

 by Muhlhauser. By mixing together fine coke, sand and salt, 

 packing the mixture round a carbon rod in an oblong box of fire 

 brick, and connecting the ends of the carbon core with the termi- 

 nals of a transformer, the entire mass could readily be raised to a 



