LUEDEKING — PHYSICO-CHEM. STUDIES IN FATTY ACID SERIES. 637 



The absolute magnitudes of the deviations of the observed 

 from the calculated specific heat is inversely to the molecular 

 w^eights of the acids, greatest for formic, least for butyric acid. 

 The smaller the molecular w^eight, the more nearly the first hy- 

 drates are the greatest deviations observed ; thus for formic acid 

 the first maximum lies nearest, and for butyric acid farthest from 

 the starting point. 



For further instruction I have calculated the molecular heats 

 of several mixtures of each acid and water, and subtracted from 

 these values the molecular heat of the water in them. The mo- 

 lecular heat is, as is well known, the product of molecular weight 

 and specific heat. The values so obtained are laid down in the 

 following table. The first column (fi) shows the number of mol- 

 ecules of water in the mixtures ; column w gives the molecular 

 heat of the water in the mixtures ; the other four columns are 

 headed by the names of their respective acids. Each contains two 

 subcolumns, of which the first gives the molecular heat s^ found, 

 \vhile the second gives the difterences (J) between this and the 

 molecular heat of the water in the mixture given in column ;//. 



With increasing molecular weight these difierences also in- 

 crease, being least for formic acid and greatest for butyric acid. 

 Whilst for acetie, propionic and butyric acids the values increase 

 with the number of equivalents of water added, the reverse is the 

 case for formic acid. Formic acid behaves exactly like salt solu- 

 tions in this respect, while the other three resemble tartaric acid. 



My first experiments in Leipzig were made by a very conveni- 

 ent and exact method devised by my honored Professor, G. Wie- 



