I,UEDEKING — PHYSICO-CHEM STUDIES IN FATTY ACID SERIES. 625 



On the Specific Heats, Specific Gravities, and the 

 Heats of Hydration of the Acids of the Fatty 

 Series, and their mixtures -with Water. 



By Dr. Charles Luedeking. 



Chemical composition and physical properties are day by day 

 shown to be more and more correlated, and so much so that the 

 standpoint of scientists to-day in many departments of chemistry 

 and physics has been solidly based on the tacit mutual under- 

 standing, that the differences of certain physical properties are 

 but the expression of the difference in the chemical constitu- 

 tion, so that from this latter we may draw definite conclusions 

 concerning the former and vice versa, although just in these 

 latter times many of the rules formerly accepted as true 

 have been shown to be erroneous. Where discrepancies occur 

 and the universal law does not hold, we by no means abandon 

 our general theorem, but consider that the discrepancy is due to 

 complexity of conditions not fully understood, or that the theory 

 from which we draw our conclusions is not yet fully developed, 

 so that the constants we calculate have no definite physical 

 meaning, as this is the case with the conception of molecular 

 volume, etc. 



Amongst substances that show irregularities in their corre- 

 sponding physical properties we may count the lower members 

 of the fatty acid series whose vapor densities are, for example, in 

 a singular way anomalous. 



It seemed to me that it would be desirable to study this series 

 more thoroughly. I desired especially to determine whether or 

 no the "gasogen" molecules of these acids C^HsnOi are united 

 in the liquids to form complex ''liquidogen" groups (C„H2„02)na 

 that under certain conditions again split up into ;;/ molecules 

 C„H,..0, 



To advance a little to the solution of this question I deter- 

 mined the specific gravities, specific heats and heats of hydration 

 of the first four members of the fatty acid series as well as of their 

 mixtures with increasing equivalents of water. 



