Chemistry and Physics. 133 



furnace dendritic crystals of zirconia are deposited. If the zir- 

 conia be fused in a carbon crucible under these conditions, a but- 

 ton of zirconium mixed with some zirconia but free from cai'bon 

 and nitrogen is found beneath the non-volatilized oxide. When 

 the zirconia is mixed with an excess of carbon a zirconium car- 

 bide is obtained containing from 4 - 22 to 5*10 per cent of carbon. 

 It has a metallic appearance and a brilliant fracture, and when 

 fused with an excess of zirconia yields pure zirconium of specific 

 gravity 4*25 which scratches glass and rubies easily and resem- 

 bles closely the zirconium described by Troost. If the carbide 

 contains more than 5 per cent of carbon, it inflames somewhat 

 rapidly when exposed to the air. Silica in an arc of the same 

 intensity melts almost immediately and is in complete ebullition 

 after six or seven minutes. The vapors condense to a slightly 

 bluish white powder consisting of a mixture of amorphous silica 

 with small opalescent spheres which scratch glass easily and have 

 a specific gravity of 2*4. About 20 grams of silica can be vola- 

 tilized in from 10 to 15 minutes, the condensed product being 

 very easily attacked by hydrogen fluoride and by alkalies. 

 Under these conditions, silica is also reduced by carbon, yielding 

 a crystalline silicon carbide. 



Troost has suggested the utilization of the volatility of silica 

 for the purpose of separating it from zirconia or thoria. If finely 

 pulverized zircon be mixed with an excess of carbon, compressed 

 into small cylinders, placed in a carbon disk and subjected to the 

 action of an electric arc in a closed vessel through which a cur- 

 rent of carbon dioxide is passed, the silica volatilizes very rapidly, 

 giving a thick black smoke due probably to silicon. The residue 

 contains only 1*5 per cent of silica. Similar results were obtained 

 with thorite and orangite, the separation of the silica in this way 

 greatly facilitating the preparation of the thoria. — C. JR., cxvi, 

 1222, 1428, 1429, 1893; Ber. Berl. Chem. Ges., xxvi (Ref.), 482, 

 669, July, Oct., 1893. G. F. B. 



4. Modification of Thomson's quadrant electrometer. — F. Him- 

 stedt describes a multicellular electrometer with one or two 

 simple modifications. The needle is suspended by a quartz or 

 glass fiber which is slightly silvered in order to conduct. For 

 the purpose of damping the movements of the needle, an astatic 

 system consisting of two magnets is suspended from a wire, which 

 forms the continuation of the axis of the needle system. These 

 magnets are placed vertical, and are surrounded by a copper 

 cylinder. The earth's directive force is annulled and the move- 

 ments of the needle system is damped by the presence of the 

 copper cylinder. 



The multicellular electrometer was first used in the Jefferson 

 Physical Laboratory in 1885, and the original instrument is now 

 in the Signal Service Bureau at Washington. — Ann. der Physik 

 und Chemie, No. 12, 1893, pp. 752-755. j. t. 



5. Coating aluminium with other metals. — At a meeting of the 

 Physical Society, Berlin, Dec. 1, 1893, Professor Neesest de- 



