RECENT ADVANCES IN SCIENCE 565 



on the other hand, that the atomic heat will give a constant 

 value (5/2)R. Lindemann points out that the problem may- 

 be settled provided sufficiently accurate data are obtainable 

 for the chemical constant of a number of individual substances. 

 Such data are furnished by the work of Egerton {Phil. Mag., 

 Jan. 1920), and the results show decisively that the atomic 

 heat of a monatomic gas maintains its value (5/2)R down to 

 the lowest temperatures. From this it is to be concluded 

 that the chemical constant has the dimensions of the logarithm 

 of a pressure divided by a temperature to the power 5/2. This 

 conclusion is important in that it involves the rejection of the 

 " degradation " theory of gases at low temperatures, a theory 

 upon which considerable stress has been laid in recent years. 



ORGANIC CHEMISTRY. By P. Haas, D.Sc, Ph.D., University College, 

 London. 



In October of last year (Science Progress, 191 9, 54, 

 p. 215) reference was made to a paper by Pictet and Cramer on 

 the distillation under reduced pressure of egg albumen. Since 

 then two other papers have been published by Pictet and his 

 pupils on the distillation of sodium stearate and of certain 

 glucosides. In the first paper, by Pictet and Potok {Helv. Chem. 

 Acta, 1 91 9, 2, 501), the authors describe the distillation under 

 1 2-1 5 mm. of 1 kg. of sodium stearate, from which they obtained 

 a distillate consisting of a mixture of hydrocarbons such as 

 decane, tetradecane, pentadecane, and tetratriacontane, the 

 latter in largest quantity. Sodium oleate under similar con- 

 ditions gave a number of unsaturated hydrocarbons including 

 nonylene, decylene, undecylene, and tridecylene. The physical 

 properties of the saturated and unsaturated hydrocarbons 

 agree with those occurring in Pennsylvanian petroleum, which 

 fact is regarded as supporting Engler's hypothesis of the origin 

 of natural petroleum from the fats of marine plants and animals. 

 The entire absence of cyclic hydrocarbons and optically active 

 naphthenes among the products of distillation, in the author's 

 opinion, points to a different origin for these compounds when 

 they occur in natural petroleum, where it is assumed that 

 they may be derived from the decomposition of such substances 

 as the resins or terpenes. In the second paper, Pictet and 

 Goudet {Helv. Chem. Acta, 191 9, 2, 698) draw attention to the 

 fact that, although the majority of naturally occurring gluco- 

 sides are lsevorotatory, they yield glucose on hydrolysis ; by 

 the distillation under reduced pressure of salicin, arbutin, 

 and phloridzin, the authors have in each case obtained a certain 

 quantity of lsevoglucosan ; since they have also been able to 



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