REVIEWS 165 



outlined is designed to teach the pupil the elements of General Chemistry through 

 the medium of the rural phenomena which he finds around him. The setting-up 

 of each experiment is clearly detailed and illustrated by a diagram where necessary, 

 and when the scholar has successfully performed the experiment he is led to draw 

 conclusions for himself. The author rightly lays stress on the necessity for 

 making the pupil write a full description of each experiment from his rough 

 laboratory notes and then stating his deductions, giving his reasons for arriving 

 at such deductions. 



Useful paragraphs in italics are inserted throughout the text with the object of 

 drawing the teacher's attention to suitable elaborations of the experiments and of 

 indicating the lines for their subsequent discussion. 



The book is eminently practical throughout, and is obviously based on sound 

 teaching experience. If the teacher follows out conscientiously the general 

 principles of the course he cannot fail to inculcate in young students the proper 

 scientific spirit of experiment and observation. The ground covered is consider- 

 able, the latter sections including elementary biological chemistry, but ample 

 latitude as regards the sequence of experiments is allowed to the teacher. We 

 doubt whether the whole course could be completed within the ordinary school 

 year, when allowance is made for the mishaps and want of confidence of pupils 

 new to scientific experimentation. 



Alex. Rule. 



Practical Physical Chemistry. By Alexander Findlay, M.A., Ph.D., DSc. 

 [Pp. xvi + 327, with 104 figures in the text. Third edition, enlarged.] 

 (London: Longmans, Green & Co., 1914. Price 4s. 6d. net.) 



Professor Findlay's text-book of practical physical chemistry is so well known 

 to teachers and students of physical chemistry in this country that little more need 

 be done than to draw attention to the fact that a new edition — the third — has 

 appeared. 



Several important additions have been made, such as the determination of 

 vapour densities by Blackman's and by Menzies' methods, the analysis of binary 

 mixtures by vapour density methods, measurement of molecular weights of 

 dissolved substances by the lowering of vapour pressure, the determination of 

 the solubility and hydrolysis of salts by conductivity measurements, decomposition 

 and ionic potentials, and the solubility of gases in liquids. Several references are 

 given to original papers. 



A very important question is that of the heating of thermostats, and the author 

 has devoted considerable space to its discussion. There can no longer be any 

 doubt that for efficiency and regularity the electrical method surpasses the old 

 gas-heating method. It is more costly to run, but on the other hand the life of the 

 thermostat itself is prolonged indefinitely, and above all the control is more sensitive. 



As regards the conductivity method of determining the solubility of sparingly 

 soluble salts, the reviewer has found that silver chromate is rather useful, since 

 it is sufficiently soluble to give good conductivity readings and at the same time its 

 hydrolysis is negligible, which is not the case with the more frequently employed 

 lead sulphate. 



The book has already stood the test of extensive use, and with the extra 

 matter now incorporated can be heartily recommended to all teachers of physical 

 chemistry. The ideal combination appears to be " Findlay " for the actual course 

 followed, and " Ostwald-Luther " as an indispensable work of reference. 



W. C. McC. Lewis. 



