i 9 2 SCIENCE PROGRESS 



Inorganic and Physical Chemistry which are being issued under 

 the direction of Prof. Alexander Findlay. 1 



Mr. Le Bas is well versed in the extensive literature of the 

 subject, and in his previous contributions he has already 

 identified himself with its study. His present work has in- 

 volved a very considerable amount of preparation, extending, 

 as he informs us, over a period of eight years. His book shows 

 him to be an acute, painstaking, and well-informed critic, and 

 it may be accepted therefore as the most authoritative exposi- 

 tion of the present condition of the subject that has hitherto 

 appeared. We purpose in what follows to give a concise sum- 

 mary of the more significant additions to knowledge to which 

 it leads. 



Mr. Le Bas arranges the subject-matter of his work, so 

 far as it relates to the point of view under consideration, in 

 the following groups : Hydrocarbons ; Halogen compounds ; 

 Organic compounds containing oxygen ; Sulphur, nitrogen, 

 phosphorus, arsenic and antimony compounds ; Miscellaneous 

 compounds of other elements. Such a scheme of classification 

 is probably the most convenient that could be devised with 

 the material at present available, and it will be desirable there- 

 fore to adopt it here. 



Of all known groups of liquids the one which may be pre- 

 sumed to lend itself best to the recognition of physico-chemical 

 relationships is that of the hydrocarbons. To begin with, 

 their number is relatively large, and they may be sub-divided 

 into well-defined classes, the members of which possess simple 

 and progressive relations among themselves and to the mem- 

 bers of other groups. Accordingly they enable the influence 

 of homology, isology, structure, grouping, substitution, and 

 other constitutive changes to be traced more readily than in 

 the case of any other comprehensive class of compounds. 

 As a rule, too, the disturbing effect of " association " is less 

 frequently observed among the hydrocarbons than in other 

 groups of organic compounds, as, for example, in that of the 

 alcohols and certain other oxygenated substances. 



Much of what is to be understood by these terms was, 

 of course, quite unknown to Kopp and his immediate suc- 



1 The Molecular Volumes of Liquid Chemical Compounds from the Point of 

 View of Kopp. By Gervaise Le Bas. (London : Longmans, Green & Co., 1915.) 

 See also Science Progress, April 1914. 



