144 Notices respecting New Books. 



equations deduced mathematically from the experimental 

 values, and have found that both methods lead to precisely 

 the same conclusions as to the existence and position of the 

 breaks. The publication of these results has unfortunately 

 been delayed, but the partial examination of one case by the 

 two methods will be found in the Ber. d. deutsch. chem. Ges. 

 xxiv. p. 3334. 



Since writing the above my attention has been called to the 

 fact that Prof. Lunge has questioned the accuracy of my sul- 

 phuric-acid density determinations (Journ. Soc. Chem. Ind. 

 1890, p. 1017). His criticism is based entirely on bis own 

 misrepresentation of the facts of the case. My answer to him 

 will be found in the Chem. News, vol. lxiv. p. 311. 



December 18, 1891. 



XIII. Notices respecting New Boohs. 



Solutions ; being the Fourth Part of a Teoct-BooTc of General 

 Chemistry. By W. Ostwald, Professor of Chemistry in the 

 University of Leipzig. Translated by M. M. Pattisojs" Mtjir. 

 London : Longmans, Green, and Co. 1891. 



A MONG- the many problems which lie on the borderland of 

 -£*- Physics and Chemistry, undoubtedly the one of greatest im- 

 portance, and at the same time one of the most difficult, is the 

 construction of a theory to account for all the known properties of 

 bodies in the liquid state. The chemist, recognizing that the liquid 

 state is most favourable, if not absolutely essential, to the occur- 

 rence of chemical reactions, hopes to obtain from such a theory an 

 insight into the nature of chemical affinity and some knowledge of 

 the arrangement of atoms in a molecule. The physicist, on the 

 other hand, regarding the same question from a mechanical point 

 of view, expects that the theory will enable him to ascertain the 

 magnitudes of the forces which act between and within molecules ; 

 and, further, by a consideration of the phenomena of electrolysis, 

 he hopes to throw some light on the nature of electricity. 



As soon as the laws of gases had been experimentally demon- 

 strated, it occurred to physicists that these might be deduced by 

 considering the molecules of a gas as small hard particles in rapid 

 motion, constantly in collision with each other, and exchanging 

 their velocities during such encounters. The fact that all gases 

 behaved in an exactly similar manner indicated that their particles 

 were so small in comparison with the distances between them, that 

 all the relations of pressure, temperature, volume, &c. might be 

 considered as resulting from forces due to this motion. On com- 

 pressing gases, however, so that the condition of relatively great 

 separation of the molecules no longer exists, a new set of forces is 

 brought into play, the mutual actions, namely, of the molecules 

 themselves. These forces cause the molecules to cling or cohere 



