424 Dr. C. K. A. Wright on the Relations between 



Substance. 



Affinity-value. 



Boiling-point. 



Water 



+ 57 i> } Diff.=-57-9 



till} ™ ff -=+73' 9 

 {**} Diff.=+43-8 



lSSll ™=+ e ™ 

 awl) Diff.=+97-fl 



-200 J Diff '=- 3 °0? 



I 2 8 ° )? } DifT.= + 120? 



105 } Diff.=+40 



j^ } Diff. =+ 39 



5;6 } Diff.=+44 

 350 I „.„ 

 Above 350 ) Dlff ' P osltlve ' 





Marsh-gas 



Carbon dioxide 



Methylic alcohol 



Ethylic alcohol 



Acetic acid 



Amylic alcohol 



Valeric acid 



Cetylic alcohol 



Palmitic acid 





In connexion with this, it may be noticed that aldehydes and 

 ketones usually boil at higher temperatures than the hydrocar- 

 bons from the formulae of which their formulae are deducible by 

 replacing H 2 by — e.g. dimethyl and ethylic aldehyde, diamy- 

 lene and borneol, cymene and cuminic aldehyde, propane and 

 acetone, heptane and butyrone, ethylbenzene and methyl- 

 phenyl-ketone, &c. Hence it may be inferred that, when the 

 requisite data are extant for calculating the affinity-values of 

 these classes of substances, it will be found that the value for 

 an aldehyde or ketone is higher than that for the corresponding 

 hydrocarbon ; and probably the same remark applies to bodies 

 represented by formulae of character analogous to that of ethy- 

 lene oxide (§ 32). Thus it will probably be found that the affi- 

 nity-value for propane is less than 59*9, the value obtained for 

 acetone; whilst it must be above 21*7, the value found for 

 marsh-gas. 



37. The rule enunciated above, connecting the change in 

 boiling-point and in affinity-value of a body by the performance 

 of a given operation, although holding in every case where only 

 a single operation is performed (e. g. hydrocarbonous, or hy- 

 droxylic methylation, or substitution of H 2 by O), and also hold- 

 ing in many cases where a succession of operations is performed, 

 is nevertheless not invariably observed in cases when several 

 operations are consecutively performed, some of which would 

 tend to cause an alteration in one direction and some in another. 

 And in point of fact such could not fail to be the case, since the 

 alterations in boiling-point are not always directly proportionate 

 to the alterations in affinity-value, but only vary in the same di- 

 rection with them ; hence the algebraic sum of a series of altera- 

 tions in affinity-value produced by a succession of operations 

 may readily be +, whilst the algebraic sum of the corresponding 

 alterations in boiling-point may be — , and vice versa, A case 



