October 13, 1923] 



NA TURE 



53^ 



fatal. They are not likely to be bitterly personal ; 

 for at the start all questions will concern classes and 

 not individuals'; it is sure to be recognised that in- 

 dividuals already existing are given the benefit of every 

 )ossible doubt. Again, minorities are likely to resent 

 cclusion rather than inclusion ; the hostility of a 

 linority whom it is proposed to exclude is clearly not 

 important as that of one which, by its secession, can 

 lin the scheme. Further, a registering body would 

 jrobably have little difficulty in securing immediately 

 bome official position and recognition. These reasons 

 ^eem to point clearly to registration as the first task 

 >f the representative body ; but, since registration in 

 Science is not a matter of primary importance, we 

 'would make it clear that we do not think it worth 

 while to establish a registering body unless it is under- 

 , stood that, when this part of its work is concluded. 

 It is to develop wider activities. 



Synthetic Colouring Matters. 



[Synthetic Colouring Matters : Dye-stuffs derived from 

 Pyridine, Quinoline, Acridine and Xanthene. By 

 Prof. J. T. Hewitt. (Monographs on Industrial 

 Chemistry.) Pp. xi + 405. (London: Longmans, 

 Green and Co., 1922.) 145. net. 



IT is probable that when the monographs on colour- 

 ing matters which are promised in the intro- 

 iuctory note to Sir Edward Thorpe's series on industrial 

 chemistry have been published, they will represent as 

 complete a compilation of the essential facts as exist 

 any language. Moreover, they will probably form 

 convenient source from which those who wish to 

 )btain full information on this important branch of 

 )rganic chemistry can readily do so without having 

 jto spend time and energy in consulting such cumber- 

 )me literature as that of the Fortschritte. The first 

 wlume to appear, that on the " Natural Colouring 

 latters," by Perkin and Everest, is already known 

 md appreciated by chemists, and we have now to look 

 [forward to the publication of no less than six volumes 

 Ion synthetic colouring matters by authors who should 

 enow what they are writing about. The first of these 

 ^volumes to appear has the title given at the head of 

 this review, and sets a standard which augurs well for 

 le success of the series. 



Probably few books are more difficult to write (or 

 to read) than those which deal with a highly specialised 

 and commercialised branch of science, such as that 

 which includes the synthetic colours. It would not 

 be so bad if scientific literature alone had to be sum- 

 marised, because in that case the author's task of 

 discriminating between fact and fable would be 

 reduced to a minimum. With the synthetic colours, 

 NO. 2815. VOL. I 12] 



however, much of the grain is hidden under the mass 

 of chaff which constitutes the patent literature, and the 

 difficulties of winnowing are great. It is difficult to 

 understand why so much money and energy are 

 devoted to the collation of chemical patent literature 

 when, as most people know, much of it is untrue and 

 a great deal of the remainder misleading. Chemical 

 patent literature is, and always has been, and probably 

 always will be, written by lawyers for lawyers ; and it 

 will probably always be the case, in spite of restrictive 

 legislation, that the manufacturing firms concerned 

 will often be inclined to place no small value on any 

 publication which tends to mislead their competitors, 

 and where some is false all must be suspect. Still, in 

 many cases, the sole source of information respecting 

 the synthetic colours lies in the patent Hterature and, 

 in consequence, an author has to exercise a wise dis- 

 cretion in sifting and arranging all the material which 

 comes to his hand. It follows, therefore, that the 

 possession of a wide knowledge, not only of his subject 

 but also of the technique of his subject, is essential if 

 the result is to be in any way comparable with the 

 energy expended, and, probably, no one is more fitted 

 than the author of this work — an old and honoured 

 worker in many of the fields he describes — to undertake 

 the task he has accomplished so admirably. 



Prof. Hewitt's work is a readable book, although it 

 contains a mass of complex information, and its read- 

 ability is due to the manner in which the author has 

 summarised and, in some cases, criticised the material 

 he has collected. His criticism is, however, neither 

 carping nor hostile, but is always expressed in a 

 detached and almost humorous manner, which is so 

 characteristic that it cannot fail to raise a smile upon 

 the lips of those to whom he is personally known. 



Although originally intended to be a book on the 

 acridine and xanthene colouring matters, it was 

 ultimately found necessary to include those derived 

 from pyridine and quinoline, and the first four chapters 

 are devoted to a description of these bases and the 

 colours obtained from them. It is perhaps fortunate 

 that the change was made, because it enabled the author 

 to include a description of the cyanine group, many 

 members of which are important photographic sensitis- 

 ing dye-stuffs. The next five chapters are devoted to 

 the acridine derivatives and contain an exhaustive 

 account of these colouring matters. Chapter x. deals 

 with the pyrone ring, and introduces the history and 

 description of the oxonium salts. The subject-matter 

 of this chapter naturally leads to a description of the 

 colouring principles of flowers, but one finds, with 

 some regret, that there the author breaks off and refers 

 the reader to the previous monograph by Perkin and 

 Everest. Surely a little overlapping in this series 



