114 Dr. E. Obach on Relationship between Specific 



vaporization those found by R. Schiff* in 1886. The latent 

 heats of the alcohols and acids are those obtained by Favre 

 and Silbermannf, whereas for methyl formate J, propylic 

 alcohol, and the benzoic esters they had to be calculated by 

 Trouton's§ relation from the molecular weight and the 

 absolute boiling-temperature. This relation can be expressed 



T 



by the formula A/ = C^r, where V is the latent heat of vapori- 

 zation, T the absolute boiling-temperature ||, M the molecular 

 weight, and C a constant ; and since it has been entirely con- 

 firmed by SchifF's subsequent researches, it can confidently be 

 applied to the calculation of the latent heat of most bodies, 

 especially that of intermediate members of a series of chemically 

 related compounds. The average value of the constant C, 

 found by SchifT, is 20*8 ; but for the alcohol series I adopted 

 the figure 25*86, deduced from Favre and Silbermamr's de- 

 termination of the latent heat of water, which gave practically 

 the same result as that found by Regnault, Andrews, and 

 Berthelot. This constant is not very different to that deduced 

 directly from the alcohols, viz. 26*14. 



In the following Tables I. and IV. the calculated values of 

 the latent heats are enclosed in brackets in order to distinguish 

 them from those actually found by experiment. 



Table I. gives the latent heat of vaporization X, the specific 



inductive capacity K ; and the quotient ^ for the principal 



esters of formic acid. Table II. similarly gives these values 

 for the esters of acetic acid, and Table III. for the ethyl esters 

 of the principal monobasic fatty acids ; the esters of formic 

 acid being represented by the general formula H . C0 2 

 (C w H 2;i+ i), those of acetic acid by CH 3 . C0 2 (C a H 2w+ i), and 

 the ethylic esters of the fatty acids by (C»H 2% _ 1 0)0 C 2 H 5 . 

 Since no experimental data for the latent heat of the benzoic- 

 acid esters C 6 H 5 . C0 2 (C^H2 W+ i) are available, this series of 

 compounds will be referred to later on (vide Table V.). 



Table IV. gives the experimental results for the saturated 

 monatomic alcohols (0 n H 2?l+1 ) OH. In Tables I., II., and IV. 



* Liebig's Annal. vol. ccxxxiv. pp. 338-350 (1886) ; also Beiblatter zu 

 Wied. Annal vol. x. pp. 689-692 (1886). 



t Landolt Bornstein's Tables, pp. 189-190 (1883). 



% The values given for methyl formate by Andrews and Berthelot 

 seem too high. 



§ Phil. Mag. [5] xviii. pp. 54-57 (1884).. 



|| The boiling-temperatures are mostly taken from the latest edition of 

 Beilstein's Handbuch der organischen Che?nie, and nearly ail refer to 

 the normal pressure of 760 milJim. 



