70 
Proceedings of the Royal Society 
Monday , 21 st February 1870. 
Professor KELL AND, Vice-President, in the Chair. 
The following Communications were read : — 
1. Note on the Atomic Volume of Solid Substances. By 
James Dewar, Lecturer on Chemistry, Veterinary Col- 
lege, Edinburgh. 
The investigation of the volume retained by different elementary 
substances, when combined in the solid condition, has attracted 
the attention of many chemists. We have only to look at the 
laborious memoirs of Schroter, Kopp, Playfair and Joule, Boullay, 
Pilhol, and others, to be convinced of the great amount of labour 
expended on the subject. Nor is it at all remarkable that so many 
workers should take to this field of research, when we remember 
the simplicity of the laws regulating the combining volumes of 
gaseous substances, and the probable extension of some such similar 
law to the solid condition of matter. Emboldened by analogy, tfie 
forementioned workers endeavoured to find some constant to which 
volumes of elements and compounds held the relation of some 
simple multiple, and thus extend the apparent simplicity of Prout’s 
law of combining weights to combining volumes. The great object 
in view w r as evidently to extend the speculations and laws of Dalton 
and G-ay Lussac to the volumes of solid substances, and thus to 
arrive at some general explanation of the results. However credit- 
able the desire to reveal simplicity from out of the apparent chaos, 
no one, in examining the subject, can help arriving at the conclusion 
that the means employed to extract the seeming harmony from the 
results were purely arbitrary. It does not follow, however, that 
the results were fruitless, although no great generalisation was 
discovered. The solid state of matter is relatively far more com- 
plicated than either the liquid or gaseous conditions. The uni- 
formity of expansion of gaseous matter, and the easy comparison 
of liquid substances under similar conditions, enable us to arrive 
at some satisfactory conclusions regarding the volume in these 
states : but, in examining solid matter, we have no guarantee 
