504 SCIENCE PROGRESS 



metals, not one word is said of the work done by Russell, Veley and others 

 showing the part that is played by nitrous compounds. Under " Modern methods 

 of writing complicated equations," printed in Clarendon type, we have the 

 following choice morsels : 



" An equation such as that representing the action of nitric acid on copper can 

 readily be written in stages. In such a case it is perhaps simplest to assume that 

 the oxygen of the nitric acid is used up in converting the metal to oxide, the latter 

 then uniting with more nitric acid to form the nitrate. As a preliminary to 

 writing the equation, the stage to which the nitric acid is reduced must be 

 determined experimentally and the formula of the nitrate must be known. The 

 steps in the action of nitric acid on copper are as follows : — 



Adding up — 



(i) 2HN0 3 = H.,0 + 2NO + 3O. 



(2) 3CU + 30 = 3CUO. 



(3) 3 CuO + 6HN0 3 = 3Cu(N0 3 ), + 3HA 



3Cu + 8HN0 3 = 3Cu(N0 3 ) 2 + 2NO + 4H,0." 



What has the chemist to do with what " is perhaps simplest to assume " ? His 

 duty is to ascertain, as far as possible, what actually happens ; it is pretty certain 

 that the picture here painted for us is purely imaginary. " 



Of late years, we have had " Reform methods " introduced of teaching modern 

 languages and even practical methods of teaching the classics ; in fact, the methods 

 of teaching almost every subject have been under consideration. Chemistry 

 almost alone — to judge from the text-books, of which there is an unceasing flow — 

 remains unreformed and there is little or no relation between the work of the 

 schools as tested in examinations and the practice of the workshop and factory : 

 the first lesson learnt by the B.Sc. on his entrance into life, as a rule, is that he 

 has wasted precious years in useless labour ; too often his mind has been so 

 unhinged that he fails to recover himself and remains but a laboratory drone for 

 the rest of his career. These are the things University Commissioners should 

 consider — not the provision of examination halls and palatial buildings for the 

 preservation of red tape. To stem the ruinous tide of democracy and socialism, 

 we need absolute free trade in University teaching : above all things, at the 

 present moment, we need thinking men — not mumblers of shibboleths. 



H. E. A. 



Treatise on Dynamics. By A. Gray, LL.D., F.R.S., and J. G. Gray, D.Sc. 

 [Pp. xvi + 626] (Macmillan & Co. Price io.r. net.) 



THE previously published works of Prof. Andrew Gray, characterised as they are 

 by thoroughness and explicitness and imbued with the scientific spirit, lead us to 

 commence the perusal of this work with not a little expectancy and it may 

 be said at once that we have not been disappointed. The careful enunciation of 

 first principles, the neat mathematical analysis and the applications of the 

 principles discussed to the solution of a large number of problems of scientific and 

 practical interest, make the work one of real value to students of pure science 

 and engineering. In the opening chapter, the kinematics of a moving point 

 are dealt with, commencing with definitions and the conceptions the writers have 

 of speed and velocity ; we are tempted to dwell upon the importance of the 

 distinction made by the authors between an instant and an interval of time, 

 as this difference is not only of importance in the study of dynamics but also helps 

 to solve the famous paradox of Zeno and to a clearer understanding of the 



