Notices respecting New Boohs. 303 



expected to know concerning the physics of this compound. 

 Here, for example, we find notes on the tension of aqueous 

 vapour, the sources of the water found in nature, the nature of 

 distillation, the decimal system, specific and latent heat, crys- 

 tallography, diffusion, &c, together with many notes on the 

 subject of solution. In view of this question, which has become 

 so prominent of late years, the author says : — " For my part, I think 

 that the study of the physical properties of solutions (and especially 

 of weak ones) which now reigns, cannot give any fundamental and 

 complete solution of the problem whatever (although it should add 

 much to both the provinces of physics and chemistry), but that, 

 parallel with it, should be undertaken the study of the influence of 

 temperature, and especially of low temperatures, the application to 

 solutions of the mechanical theory of heat, and the comparative 

 study of the chemical properties of solutions. The beginning of 

 all this is already estabished, &c." (Vol. I. p. 89, note 45). With 

 respect to the view that solutions are to be regarded as " a 

 particular state of definite compounds," i. e. the " hydrate theory," 

 he says : — " I repeat, however, that for the present the theory of 



solutions* cannot be considered as firmly established By 



submitting solutions to the Daltonic conception of atomism, I hope 

 that we may not only attain to a general harmonious chemical 

 doctrine, but also that new motives for investigation and research 

 will appear in the problem of solutions, which must either confirm 

 the supposed theory or replace it by another fuller and truer one " 

 (Vol. I. p. 106, note 70). 



The second chapter deals with the composition of water and 

 hydrogen, the third chapter with oxygen and its saline combi- 

 nations, the fourth with ozone and hydrogen peroxide and 

 Dalton's law. This association of descriptive matter with 

 theoretical deductions is another characteristic feature of Men- 

 deleeff's treatment, and lifts the work under consideration out of 

 the cut and dried method with which our text-books have so 

 generally familiarized us. Thus, after a complete description 

 of ozone and hydrogen peroxide, the author makes use of these 

 compounds to illustrate unstable chemical equilibrium (Vol. I. 

 p. 212), and then, by comparing water and hydrogen peroxide, 

 he proceeds to develop Dalton's law of multiple proportions, from 

 which flows as in natural sequence a preliminary treatment of the 

 atomic theory. The comprehensiveness of the author's grasp is 

 well seen here in the footnotes, one of which, occupying about 

 two pages of small print, deals with the vortex theory of atoms and 

 the (apparently unconnected) question of the moon's atmosphere. 



Chapters V. and VI. deal with nitrogen and air and the 

 compounds of nitrogen with hydrogen and oxygen. The seventh 

 chapter is theoretical, being devoted to atoms and molecules and 

 the laws of Boyle and Gay-Lussac and Avogadro-Gerhardt. In 

 note 29 to this chapter the author discusses osmotic pressure and 

 expresses his views concerning the dissociation theory of solution : — 



"As the conceptions of this order have been as yet but very 

 little developed, and as in regarding solutions from this point of 



