REVIEWS 781 



with for the sake of more space devoted to theory. An alkali manufacturer is not 

 likely to turn to a dictionary for information as to the mechanical outlines of his 

 own business ; but he surely ought to be able to consult it for the purpose of 

 ascertaining fully the why and the wherefore. Naturally, this is the expression 

 of a personal opinion, and it is given only for what it is worth. 



But the section on the contact manufacture of sulphuric acid shows that an 

 article dealing with an industry can be scientifically interesting — that is, of great 

 educative value and practical heip— to the technical man. 



This is the true purpose of a dictionary such as this — to point out to the practical 

 man the virtues of scientific method, and to show him that it is for him to instigate 

 research, not merely to profit by it when he finds it made to his hand. Such 

 articles as that on triphenylmethane dyes, or in yet another field, that on soils, may 

 be quoted as being likely to produce this effect. 



The metallurgy articles hardly come up to the standard, and would be much 

 improved by a more " advanced " discussion of physical and physico-chemical 

 properties; indeed, in the article "Tin" there is no section on the properties of 

 the metal at all. 



The main criticism to be levelled at the work is, in fact, that despite the great 

 influence which physico-chemical work now has upon industry, that side of the 

 subject receives far too scanty attention ; and even in the special articles there is 

 often so sharp a line drawn between theory or practice, or rather between labora- 

 tory and works, that no obvious connection is manifest. It is remarkable that the 

 important subject of surface-tension should be ignored, nor is to be found under 

 "Capillarity" in Vol. I. 



Several of the larger articles have already been cited as being of high value ; 



and among the others which call for special mention are " Starch," " Water," 



" Thermit," " Ultramarine," and many of the sections on various vegetable 



extracts. 



Irvine Masson. 



The Progress of Scientific Chemistry in our own times ; with biographical 

 notices. By Sir William A. Tilden, F.R.S. Second Edition. [Pp. xii 

 + 366.] (Longmans, Green & Co., 1913. Price ys. 6d. net.) 



Some fifteen years have passed since the first edition of this book was published, 

 and consequently this, the second edition, embodies many additions. Originally 

 the outcome of a series of" Lectures to Working Men," its eleven chapters con- 

 stitute a most interesting survey of the development of chemistry during the past 

 eighty years. Sir William Tilden is one of the comparatively few who can 

 properly claim to be competent to pass under review so fruitful a period in 

 chemistry ; for, even apart from the wide scope of his chemical interests, the fact 

 that a large section of this time lies within his own recollection gives him a special 

 title to authority, and confers a sense of perspective and proportion which no 

 younger chemist can compass. This is far from saying that the author of this 

 work is laudator temporis acti ; the significance which he evidently attaches to 

 the most recent, no less than to the earlier, developments would satisfy even the 

 most " modern '' of chemists. The said modern, however, is occasionally apt to 

 forget the debt of the past, especially of the recent past ; and such a book as this 

 does service in keeping in due prominence the great researches which last century 

 brought forth. 



In a sense, chemistry may be said to have been made during the last three 

 generations, and thus it would be small wonder if a history of this period were 



