462 SCIENTIFIC RECORD FOR 188=2. 



Berthelot supposes carbon to be. {Comptes Rendus, January, xciv, p. 

 20.) In a note following this paper Violle mentions a fact observed by 

 him in 1878, while melting some palladium, which shows the ready dif- 

 fusibility of carbon. The crucible used was of porcelain, supported in 

 an outer one of plombagine. After heating to 1500°, this porcelain 

 crucible was so permeated with carbon as to have exteriorly the ap- 

 pearance of a carbon crucible. The depth to wliich the plombagine pen- 

 etrates is proportional to the time of heating. {Comptes Rendus, Janu- 

 ary, XCIV, p. 28.) 



Marsdeu has made use of this ready diffusion of carbon in his theory 

 of the cementation process. He believes that the carbon in the state of 

 impalpable powder diffuses into the bars of iron during the heating, 

 when they are expanded and softened, thus converting them into steeL 

 {Ann. Chim. Phys., August, Y, xxvi, p. 568.) 



Spriug has submitted to compression the variety of sulphur obtained 

 in vesicles by Saint-Claire Deville, which is insoluble in carbon disul- 

 phide. Under a pressure of 8,000 atmospheres at 13° hard pale yel- 

 low blocks were produced, 4.21 per cent, of which was soluble in car- 

 bon disulphide and had been therefore transformed into the octohedral 

 variety. Hence the density of the vesicular sulphur is less than that 

 of octohedral sulphur. By obtaining the specific gravity of these blocks 

 at different temperatures. Spring measured the expansion and calcu- 

 lated for vesicular sulphur the density 1.960, the same as prismatic sul- 

 l)hur. It expands regularly up to 43°, then contracts again, so that at 

 80° it has the same specific gravity as at zero. {Nature, January, 1882, 

 XXV, p. 231.) 



Kayser has studied the condensation of gases on the surfaces of solids, 

 a phenomenon to which he gives the name " adsorption." The gases 

 used were carbon dioxide, sulphurous oxide, and ammonia, and the ad- 

 sorptive effect was noted (1) in the empty glass vessel, (2) in the same 

 filled with coarsely pounded glass, (3) in the vessel filled with brass 

 and wrought-iron turnings. By noting the pressure produced in the 

 vessel by a given volume of gas, the adsorption was determined. With 

 the solids given it was in the order: empty vessel, iron, brass, glass 

 powder. Sulphurous oxide was least condensed by the empty vessel, 

 most by the glass powder. On the empty vessel, CO2 was condensed 

 equally with NH3; on the metallic surfaces equally with SO2; and on 

 the glass surfaces less than either. ( Wied. Ann., xv, p. 634 ; Nature, 

 June, XXVI, p.l39.) 



Berthelot has investigated the absorptive action of jjlatinum for 

 oxygen and hydrogen gases, and shows that a suboxide and two hy- 

 drides are produced by it. The so-called catalytic action of platinum 

 is therefore due to a definite reduction which takes place in presence 

 of oxygen and of hydrogen, water being formed. The inflammation of a 

 mixture of oxygen and hydrogen by platinum is due to the formation 



