294 CHEMISTRY. 



of new metallic elements, of wliich fourteen have been added to the list 

 in about two years, eleven of these belonging, it is said, to the 3 ttrium 

 or cerium group. The first was Davyum, a new metal of the platinum 

 grouj) announced in 1877 by Kern ; probably a mixture. Then follow 

 ytterbium by Marignac, X by Soret, mosandrum by Smith, phillippium 

 and decipium by Delafontaine, thulium and holmium by Cleve and 

 Thalen, samarium by Lecoq de Boisbaudran, scandium by Nilson, nor- 

 wegium by Dahll, and vesbium by Scacchi. — [Nature, xxii, 232, July, 



1880.) 



OEGANIC. 



Thomsen, in a i)aper presented to the Berlin Chemical Society, has 

 attempted to base a general theory of the structure of carbon compounds 

 on thermal determinations. He does this by measuring (indirectly of 

 course) the heat of dissociation of the carbon molecule, and from this 

 and other data finding a thermal value for the combination of two car- 

 bon atoms, to form a gaseous compound, by four "links," by three, by 

 two, or by one. He thence deduces a thermal value for each link. Gen- 

 eral equations are given for calculating the heats of formation of various 

 isomers, assuming a certain linking of the atoms for each. In cases 

 where various linkings may be assumed, a determination of the heat of 

 formation may determine which linking, and therefore which structural 

 formula, is the more jirobable. — {Ber. Berl. Chem. Ges., xiii, 1388, 1392, 

 July, 1880; Nature, xxii, 512, October, 1880.) 



Beilstein and Kurbatow have examined the more volatile jDortions of 

 the petroleum of Baku in the Caucasus, with a view of comparing them 

 with the corresponding i)ortions of American petroleum. It had been 

 observed that for the same boiling point the Caucasus fractions had a 

 greater specific gravity. Hence a distrust of these Caucasus illuminat- 

 ing oils, until it was shown that they had an illuminating power 10 per 

 cent, higher than the American. The fractions obtained by the authors 

 were: one boiling below 80°, with a gravity of 0.717; one from 80° to 

 S50, 0.733; one from 85° to 90°, 0.711; one from 90° to 95°, 0.745; one 

 from 950 to 1000, 0.748; and one from 100° to 105°, 0.752. Below 80° 

 American petroleum yields hexane of gravity 0.GG9, while between 95° 

 and 100° it gives heptane of gravity 0.699. To ascertam the cause of 

 this difference the 80° to 85° fraction was agitated with fuming sulphuric 

 acid; but no aromatic hydrocarbons were thus detected. Since analysis 

 gives the formula Cu H2„, the fraction was examined for the olefines 

 with bromine; but no action took place in the cold. On further study 

 it appeared that these hydrocarbons belonged to a series obtained by 

 hex-hydrogenatiug the aromatic hydrocarbons, the first member of which 

 is hexahydrobenzene. Subsequent investigation showed the same series 

 to be present in American petroleum, though in much smaller amount. — 

 {Ber. Berl Chem. Ges., xiii, 1818, 2028, 1880.) 



Vincent and Delachanal have determined the density and the expan- 

 sion coefficient of methyl chloride at various temperatures. For this 



