Affinity and Dissected [Structural) Formula, 



419 



acetate from acetic acid may be viewed as made up of the two 

 operations : — 



Conversion ofC 2 H 3 O.OH into C 2 H 3 . . CH 3 (hydroxylic 



methylation) . 

 Conversion of C 2 H 3 . . CH 3 into C 2 H 3 . . CH 2 . CH 3 



(hydrocarbonoUs methylation) . 



The heat-absorption due to the first operation is considerably 

 greater than the heat-evolution due to the second. Thus the 

 algebraic sum of the two heat-disturbances is negative in the 

 following instances, saving butyric acid and its ether, in which 

 case the irregularity is brought about by the erroneous value 

 found for ethyl butyrate (§ 16). Taking the corrected value, 

 however, a negative algebraic sum is obtained in each case. With 

 ethyl formate a negative value is found even when the uncor- 

 rected value is taken. 



Acid. 



Affinity- 

 value of 

 acid. 



Affinity-values of corre- 

 sponding ethylic ethers. 



Heat-disturbance. 



Directly 

 calculated. 



Corrected. 



Directly 

 calculated. 



Corrected. 



Formic . . . 



Acetic 



Butyric ... 

 Valeric ... 



97-2 

 1100 

 146-3 

 149-5 



920 

 147-7 



860 



91-5 



1100 



114-4 



-5-2 

 + 1*4 



— 112 



-18-5 

 -36-3 

 -351 



In the case of amylic ethers, it seems that four successive hy- 

 drocarbonous methylations only evolve a little more heat than is 

 absorbed during the first hydroxylic methylation. 



Acid. 



Affinity- 

 value of 

 acid. 



Affinity- values of corre- 

 sponding amylic ethers. 



Heat -disturbance. 



Directly 

 Calculated. 



Corrected. 



Directly 

 calculated. 



Corrected. 



Acetic 



Valeric . . . 



110 

 149-5 



967 



114 4 

 151-3 



-13-3 



+4-4 

 fl-8 



30. C. The rule also holds in the case of alcohols and their 

 simple ethers. The formation of an ether from an alcohol may be 

 viewed as the sum of one hydroxylic and n hydrocarbonous me- 

 thylations; and in all the known instances of this class the heat- 

 disturbance due to this sum is such as to prove that the hent- 

 absorption during hydroxylic methylation is considerably greater 

 than the heat-evolution during hydrocarbonous methylation. 



2 E 2 



