476 SCIENCE PROGRESS 



temperature. The biographer makes a mistake in supposing that Sutherland's 

 law of viscosity variation is necessarily associated with another, and less 

 reliable, of Sutherland's efforts, viz. the deduction of an inverse fourth 

 power law of force between molecules. The viscosity law is on a much broader 

 basis, and is completely independent of the actual law of molecular force. 

 It is significant that, although the inverse fourth power law seldom finds 

 acceptance among physicists, the viscosity law is generally held to be sound, 

 and has recently received confirmation in the more formal analysis due to 

 S. Chapman. 



Sutherland had, besides, great literary ability, and was deeply interested 

 in music and art. These the biographer also touches upon ; and the picture 

 he is able to draw is that of a man of many and varied achievements — a man 

 to be admired and loved, but, withal, somewhat pathetic. 



A. O. Rankine. 



CHEMISTRY 



Thermodynamics and Chemistry. By F. H. Macdougall, M.A., Ph.D. 

 [Pp. V + 391.] (New York: Wiley & Sons; London: Chapman & 

 Hall, 1921. Price 305, net.) 



Prof. Macdougall has, in his own words, set himself the task of writing 

 " a book which, in addition to being accurate, logical, and sufficiently rigorous, 

 will furnish the student with numerous examples of the application of the 

 principles of the science." On the result of his work he deserves to be com- 

 plimented : the book under notice is one of the most satisfactory accounts 

 of the principles of thermodynamics, with particular reference to chemistry, 

 which the reviewer has seen. The difficulties are mostly faced and disposed 

 of honestly ; lame expressions such as " it can be shown," or " by analogy 

 we see," which appear too frequently in books on thermodynamics intended 

 for chemists, are not noticed except in the last chapter (radiation and quantum 

 theory), where a full discussion would have involved more space and 

 mathematics than would have been expected. 



Any exposition of chemical thermodynamics which is easy reading may 

 be taken as either so rudimentary as to be trivial, or so dishonestly evasive 

 and superficial as to be prejudicial to good teaching. Prof. Macdougall 

 makes free use of the elements of the calculus — he could not do otherwise 

 with justice to his subject or his readers, but the results are eminently 

 practical. " No apology is offered for the considerable number of mathe- 

 matical equations which will be found throughout the book. They are as 

 essential as chemical equations in a book on descriptive chemistry." The 

 analogy is sound : it is quite possible to write a book on chemistry without 

 formulae or equations, but it is not desirable. The collections of examples 

 and exercises at the ends of the chapters are commendable. 



The treatment of the subject follows the classical analytical methods of 

 Gibbs and Planck rather than the use of the cycles more common in elemen- 

 tary books. Whilst the former method is more elegant, it is probable that 

 beginners derive more benefit from the older treatment. For this reason, 

 the reviewer believes that the book should be read by those students who have 

 already had a brief course of elementary thermodynamics, such as is usually 

 comprised in general lectures on physics. The deduction of the Clapeyron- 

 Clausius equation given by Prof. Macdougall (pp. 123-9) would not appeal 

 to beginners so forcibly as the usual proof with a cycle. 



The teaching of thermodynamics, in the opinion of the reviewer, may best 

 follow the order adopted in dynamics. The laws of motion as given by 

 Newton are sufficient to allow of a good deal of progress being made before 

 beginning analytical methods. The reader of Gibbs can hardly fail to notice 

 the influence of Lagrange : Gibbs did for the older thermodynamics of 



