474 Transactions. — Chemistry and Physics. 



The differences of the boiling-points reach a maximum 

 early in the series, and then very slowly decrease. When 

 the boiling-points are taken at reduced pressure the rela- 

 tive decrease is larger for the same alcohols. Now, at the 

 lower temperature the liquid molecules are to a greater 

 amount associated, and consequently this maximum is caused 

 by the molecular complexity of the liquids. In all the cases 

 mentioned above the results are different, but the explanation 

 for those compounds is that the association of the vapour is 

 the cause of the abnormal behaviour. 



(3.) When the Compounds are in the Solid State. — (a.) 

 Melting-points : Among the normal acids of the oxalic series 

 the melting-points rise and fall, each term of the even series 

 melting at a higher temperature than either of its two homo- 

 logues of the odd series. If, however, the odd and even 

 members are considered separately, a minimum melting-point 

 is observed among the compounds containing an odd number 

 of carbon atoms. This was pointed out by Massol,* and is 

 shown in the following table : — 



From these data it seems probable that the numbers for 

 the melting-points in the even series will also fall to a mini- 

 mum in the neighbourhood of the C u acid. 



The substituted malonic acids behave in a similar manner. 



Here the minimum is reached when the substituent chain 

 contains five carbon atoms ; in the previous case the C 5 

 and in the fatty acids themselves the C 5 compound also shows 

 the minimum melting-point. 



In the case of the amides of the fatty acids the results are 

 not so regular. Nevertheless, it is interesting to compare 

 them. 



* Bull. Soc. Chim., 1899, 578. 



