418 



Dr. C. R. A. Wright on the Relations between 



the operations indicated by the substitution of the radicals C 2 H 5 , 

 C 3 H 7 , &c. for H), heat is developed. 



Thus ethylic, amylic, and cetylic alcohols are derivable from 

 methylic alcohol by operations symbolically indicated by the 

 replacement of an H symbol in the CH 3 group of the formula 

 of methylic alcohol by the radicals CH 3 , C 4 H 9 , and C 15 H 31 

 respectively ; hence heat is evolved in the transformation of me- 

 thylic into ethylic alcohol, and also in the conversion of this into 

 amylic alcohol, or of amylic alcohol into cetylic alcohol. Thus:— 



Affinity-values. 



Heat- 

 disturbance. 



Methylic alcohol.. 53-4 

 Ethylic alcohol ... 637 

 Amylic alcohol ... 86-2 



Ethylic alcohol ... 637 

 Ainvlic alcohol ... 86'2 

 Cetylic alcohol ... 1067 



+ 103 



+22-5 

 +20-5 



It is here noticeable that the conversion of water into me- 

 thylic alcohol is accompanied by a heat-absorption. But this is 

 not an exception to the above rule, not being a case in point, 

 there being no hydrocarbonous radical in the formula of water; 

 on the other hand, as shown in §§ 31 and 33, this fact is quite 

 in accordance with other general rules. The conversion of hy- 

 drogen into marsh-gas, however, is attended with heat-evolution. 



28. The following considerations show that heat is absorbed 

 when an operation is performed of the kind that may be termed 

 "hydroxylic methylation," {. e. symbolically indicated by the 

 substitution of the radical CH 3 for the H symbol in an OH 

 group in the dissected formula of the original substance. 



A. The rule holds in the case of acids and their compound 

 methylic ethers, whether the directly calculated affinity-values 

 of the latter or the corrected values be taken. 



Acid. 



Affinity- 

 value of 

 acid. 



Affinity-values of 



corresponding 



methylic ethers. 



Heat-disturbance. 



Directly 

 calculated. 



- 

 Corrected. 



Directly 

 calculated. 



Corrected. 



Formic 



Acetic 



97-2 

 1100 

 1463 

 149 5 



Vii'-i 



1152 



680 



87-0 



105 



1100 



i 



-31-2 

 -34-3 



-29-2 

 -23 

 -41-3 



-39-5 



1 



Butyric 



Valeric 



29. B. When an acid is converted into its ethylic ether the pro- 

 cess may be regarded as the sum of two operations — one of hy- 

 droxylic methylation absorbing heat, and one of the hydrocarbo- 

 nous methylation evolving heat. Thus the formation of ethvl 



