426 



D] 



C. li. A. Wright on the Relations between 



taken, the affinity-value differences become +24*4 and +55*3 

 instead of +44*5 and + 50*1 respectively, the algebraic sign 

 remaining unchanged in each case. 



The fact of evolution of heat during the process of polyme- 

 rizing aldehydes, olefines, terpenes, &c. is very well known in 

 numerous instances, although the exact heat-development has 

 not been accurately measured in any particular case. Kekule 

 has recently shown (Berichte Dent. Chem. Ges. vol. vi. p. 1087) 

 that when carvol is converted into its isomeride carvacrol, boiling 

 some 12° higher, much heat is developed during the reaction. 



It may hence be predicted that the affinity-value of a normal 

 acid, alcohol, hydrocarbon, &c. will be found to be higher than 

 that of the corresponding secondary or tertiary isomeride, since 

 the boiling-point usually appears to be higher; for instance, 

 normal propylic alcohol will have a higher value than isopropylic 

 alcohol. 



39. The following three cases afford apparent exceptions to 

 the generality of the preceding rule as to isomerides when the 

 uncorrected affinity-values are taken for calculation : — 



Substance. 



Affinity-value. 



Boiling-point. 



Methyl acetate 



Ethyl formate 



Methyl valerate 



Ethyl butyrate ..... 



Ethyl valerate 



Amyl acetate 



MM)} DiE -+ 50 

 ilff } Diff. =+29-5 



11} m =-i 



lis} «•- o 



\H] Diff. = 



If, however, the corrected values be taken instead, these appa- 

 rent exceptions disappear. 



Substance. 



Affinity-value. 



Boiling-point. 



Methyl acetate 



Ethyl formate 



Methyl valerate 



Ethyl butyrate 



Ethyl valerate 



g:»} Diff. =-i-o 



It] »iff=-i 



!!!} Diff.= o 



JgJ Diff.- 





It may here be noticed that if the corrected values given in the 

 Table for methyl butyrate and valerate, ethyl formate and buty- 

 rate, and amyl acetate be taken, these substances agree perfectly 

 with the general rules elucidated in §§ 16, 29, 34, and 39; 

 whereas if the directly calculated values be chosen, these bodies 

 form exceptions to most or all of the rules ; and as there is not 

 the slightest improbability in the character or amount of the cor- 



