1 64 SCIENCE PROGRESS 



elements and their compounds. There is a short account of the phenomena of 

 radioactivity, and also a chapter on Spectrum Analysis. Details of practical 

 exercises and numerical problems are appended to most of the chapters. 



In view of the assumption made by the author that the pupil has some know- 

 ledge of the principles of chemistry before the book is put into his hands, such 

 features as the mention of molecular weights and the extensive use of chemical 

 equations in the early chapters of the book without any real explanation of their 

 significance are perhaps less open to criticism. For the same reason, however, the 

 inclusion of many minor and elementary details would seem to be unnecessary. 



The text is characterised by a regrettable lack of preciseness. There is a 

 general looseness in the use of nomenclature, and the phraseology is in many 

 places unscientific. These faults are particularly marked in the early chapters. 

 For example, we find the term " carbonic acid gas," used exclusively in the first 

 few pages, giving place to " carbon dioxide " without any reason being put forward 

 for this change of style. The employment of such archaic terminology as " potassic 

 chloride " might be overlooked if the author were merely consistent, but when the 

 pupil is directed (p. 32) " to find the percentage of oxygen in potassic chlorate," 

 and in the next paragraph is instructed to " crush some potassium chlorate in a 

 mortar," he may be forgiven if some doubt arises in his mind as to the real 

 identity of this substance. 



In dealing with the detection of impurities (p. 3), the statement that "a pure 

 solid will show under the microscope all its grains to be alike in colour, texture 

 and shape" when there is no previous mention of crystalline and amorphous forms, 

 is likely to lead to confusion. 



These defects may be set down to a clumsiness in style on the part of the 

 author ; but the text contains in addition certain grave inaccuracies, which, in 

 some cases, amount to positive misstatements of fact. For example, in a para- 

 graph on the use of indicators (p. 47) phenol phthalein is stated to possess the 

 advantage, like methyl orange, of not changing colour when carbonic acid is 

 present. 



With the authqr's personal views it is not always possible to agree. After 

 devoting less than a page to the Periodic Law, he is of opinion that the periodic 

 classification " is regarded more or less as a scientific curiosity, and really serves 

 very little useful purpose." We would suggest that at least one useful purpose 

 served by this classification is to form a sound basis for the comparative descriptive 

 treatment of the elements and their compounds, and one on which the writers of 

 several modern text-books for the use of young students have relied with marked 

 advantage from the point of view of the teacher. 



We fail to see that this book in its present form can be of real service to 

 the class of pupil for which it is intended, especially in view of the existence of 

 text-books of the same scope but written on sound modern lines. Very con- 

 siderable amplification of the introductory portion is desirable, and the whole 

 text requires most careful revision with a view to the removal of such inaccuracies 



as have been indicated. 



Alex. Rule. 



A First Course in Practical Chemistry for Rural Secondary Schools. By 



William Aldridge, B.A., B.Sc. [Pp. xii + 122, with diagrams.] (London : 

 G. Bell & Sons, 191 5. Price is. 6d.) 



This is the first volume to be published of Messrs. Bell's Science Series for 

 Schools and Colleges, and it is a happy augury for the whole series. The course 



