532 Scientific Proceedings, Royal Dublin Society. 



We get 



a - x n = ae ~ M "' for first acid, 

 b -y„ =be - **»/ f or second acid ; 

 or, 



a + h - (x n + y n ) = ae~ ^'f + be~ ^»f 



The fraction of original left : — 



1 a;, + y n = a c - Mnf + & K - tenf 2 

 a \ b a + b a + b 



write 



a b 



+ b 



= n. 



m and n represent the ratio in which acids were present initially, and we 

 have m + n = 1, 



#» + y» _ percentage of acid distilled over _ P n 

 ~a+t "TOO = UK)' 



We have then 



1 - Yfin = me + ne . 



writing 



or 



e ~ Xl/ = c, and e~ Mf = c 2 



l - Yfro = mc " + m * n > 



if we write p'„ = per cent, of 1st acid coming over in ^-fractions. 

 >; i> P n = ), j, ^ncl „ „ „ „ „ 



1_ ioo~ Cl i ioo - c *- 



P n = mp' n + wp"„. 



Pure formic and acetic acids were mixed in known proportions in 

 aqueous solution, and from the percentage of the total acid distilling in each 

 fraction the composition of the mixture was determined with the aid of the 

 above expression. Various mixtures, each containing two fatty acids, were 

 similarly treated. The compositions of the mixtures, as determined from 

 the distillation results, agreed closely with the actual proportions in which 

 the acids were present. This agreement holds both when the results are 

 calculated from the formula or obtained graphically, using Fig. 7. 



