412 Prof. Masson on the Boiling -Points, Molecular 



physicists are, moreover, not in absolute agreement, though it 

 would be unreasonable to look for greater concordance in such 

 a difficult case. But the weakness of the evidence here in 

 comparison with that in the previous work lies in the fact that 

 we are here dealing with only one property, instead of with 

 the accumulation of confirmatory evidence from wholly inde- 

 pendent sources. For this reason only we must be satisfied 

 with regarding the results more as important suggestions than 

 as definite proof. 



XLV. On the Relation between the Boiling-Points, Molecular 

 Volumes, and Chemical Characters of Liquids. By Okme 

 Masson, M.A., D.Sc, Professor of Chemistry in the Uni- 

 versity of Melbourne *. 



IN one of his papers on the Periodic Law (Phil. Mag. 1885, 

 p. 259) Professor Carnelley pointed out several relations 

 between the alkyl compounds of the elements with regard to 

 the variation of boiling-point and of specific gravity. If, 

 instead of considering the specific gravities themselves, we 

 calculate from them the molecular volumes of, say, the ethyl 

 compounds of the various elements and plot a curve with 

 these values as ordinates and the atomic weights of the 

 elements in question as abscissae, the manner in which they 

 vary from one compound to another and from one period to 

 another may be compared with the variation of the boiling- 

 points, similarly plotted ; and, in spite of the broken character 

 of the curves, due to want of data and the nonformation of 

 ethides by many of the elements, the general resemblance be- 

 tween the alteration of molecular volume and the alteration 

 of boiling-point is rendered very striking. The molecular 

 volumes are, however, not really comparable, being calculated 

 from densities at ordinary temperatures ; and they cannot 

 therefore serve for the study of whatever exact relation may 

 exist between boiling-points and molecular volumes. For 

 this purpose densities at the boiling-points are required, and 

 these are known in the case of only five of the twenty or more 

 known ethides (Clarke's Table of Specific Gravity). 



Intending ultimately to complete as far as possible the study 

 of the molecular volumes of these^substances at their boiling- 

 points under atmospheric pressure, I commenced recently 

 with the haloid compounds of ethyl, using Ramsay's method, 

 slightly modified ; and certain considerations have been sug- 

 gested by a comparison of these first results with the work of 



* Communicated by the Author. 



