LUEDEKING PHYSICO-CHEM. STUDIES IN FATTY ACTD SERIES. 63 I 



all attain maximas, whereupon the curves more or less gradually 

 fall to the zero line of no condensation. All four acids on the first 

 additions of water show an increment in the specific gravity. This 

 has long been known to be the case for acetic acid, whilst to my 

 knowledge no similar experiments have been made for the other 

 three acids. 



I must state that the positions of these maximas are however 

 not constant, but vary with the temperature. 



For further instruction I have calculated the molecular conden- 

 sations, which will be found in the following table. The column 

 headed n gives the number of equivalents of water added to the 

 acids designated at the heads of the other columns. Under each 

 acid there are two columns, the first of which shows the molecu- 

 lar condensation of the acid under the assumption that the water 

 molecules remain unchanged in volume, whilst the second gives 

 the molecular condensation of the water molecule ; that is to say, 

 the total condensation divided by the number of water equiva- 

 lents, under the assumption that the acid molecule remains 

 unchanged. 



It is apparent from the table that the molecular comlensation 

 of the acids increases with increasing quantities of water, whilst 

 the molecular condensation of the water decrease's steadily under 

 the above assumption. The condensations in case of acetic, pro- 

 pionic and butyric acids are very nearly equal to one another, 

 and very much greater than for formic acid. 



THE SPECIFIC HEATS. 



For these determinations I used Kopp's method, as modified 

 by Bette/ido rf a.nd Wullncr, Pogg. Ann. cxxxiii. 



