﻿Notices respecting New Books. o27 



Ostwald treats of the limiting phenomena of volume-energy. 

 Be suggests that if it be conceivable that the volume of* a gas 

 is increased indefinitely, the volume-energy obtainable from a 

 gas would also increase infinitely, involving the consequence 

 that from a finite quantity of gas an infinite amount of heat 

 of constant temperature could be converted into kinetic energy. 

 He therefore suggests that at some very great, yet finite volume, 

 the pressure should become zero, and the gas should therefore 

 refuse to increase its volume. Instead of the expression for 



Boyle's law, pv = c, {p + k) v =c 9 where &=- — , i.e. at a volume 



'-'max 



where p = 0. Such a supposition would place an upper limit 

 to the atmosphere. Similar considerations are also applied by 

 him to gravitational energy. 



The abnormal behaviour of oxygen is, if not more, at least 

 equally difficult to explain. Some profound change must take 

 place suddenly at the pressure 0*7 millim. Whether this 

 change is of the nature of dissociation or not, cannot readily 

 he determined ; but the spectra of oxygen appear to show that 

 it is able to exist in several modifications at low pressures. 



The work described appears to us very incomplete ; yet it 

 has not been for want of time and trouble spent on it. The 

 experiments are of extreme difficulty, and it has taken close 

 on two } r ears to arrive at the results chronicled, imperfect as 

 they are. We are, however, somewhat cheered to learn that 

 the experience of Professor Mendeleeff has in this respect 

 been like ours ; that a short column of figures can express 

 the results of the labour of years. 



University College, London, 

 20th May, 1894. 



XXXVI. Notices respecting New Books. 



The Steam-Engine and other Heat- Engines. By J. A. Ewixg, 

 M.A., B.Sc, F.E.S., M.Inst.C.E. Cambridge: at the Uni- 

 versity Press. 



PROFESSOR EWING-'S article on the Steam-Engine iu the 

 Encyclopedia Britannica reads like a set of most excellent 

 lecture-notes. In the present book the Encyclopedia article may 

 easily be recognized ; but if we may dare to say so, it is like 

 recognizing the features and manners of a clever Scotch medical 

 student in an accomplished and experienced London physician. 



Although short for such a great subject, its style is polished ; 

 and because the author has not only studied his subject, but also 

 his students, the book reads very easily. Only in a very few 

 places does there seem to be any of that useless mathematics with 



