MABERY AND GOLDSTEIN. —SPECIFIC HEATS OF HYDROCARBONS, 547 



heat of vaporization of liquids at their boiling points has become of great 

 importance. FYorn a practical point of view, the greatly extended use 

 of crude petroleum and its constituents can only be economically con- 

 tinued with the aid of further information concerning the heats of 

 vaporization. Numerous inquiries from persons interested in these 

 directions attest an appreciation of further knowledge on this subject. 



In 1885 the following law was 

 proposed by Dudley, on the heats 

 of vaporization of members of a 

 homologous series.* 



" In any homologous series the 

 heat of vaporization in a unit of 

 volume of the vapor, under the 

 same conditions of temperature 

 and pressure, is proportional to 

 the density and also to the abso- 

 lute boiling point." This gen- 

 eralization was based on data 

 selected from determinations of 

 the heats of vaporization of the 

 formiates, acetates, propionates, 

 butyrates, isobutyrates, alcohols, 

 and aromatic hydrocarbons. 



With numerous members of the 

 different series of hydrocarbons 

 at hand, it was our intention to 

 determine the latent heat of the 



Series ^n"^'2n4-2^ ^n 2n' ^n 2n 1* 



But the only apparatus available 

 was constructed of glass, which E~ 

 would not withstand the high tem- 

 peratures necessary in determina- 

 tions of thehydrocarbons with high 

 boiling points, and the time was too 

 limited to permit of the construc- 

 tion of a metallic apparatus. 



For the apparatus used, we are indebted to the kindness of Professor 

 Kahlenberg of the University of Wisconsin, who allowed us to use the 



* Journ. Am. Chem. Soc , Vol. XVII., No. 12. 



