NATURE 



THURSDAY, MAY 29, 1919. 



241 



NATURAL ORGANIC COLOURING 

 MATTERS. 



The Natural Organic Colouring Matters. By Prof. 

 A. G. Perkin and Dr. A. E. Everest. (Mono- 

 graphs on Industrial Chemistry.) Pp. xxii + 655. 

 (London: Longmans, Green, and Co.,. 1918.) 

 Price 285. net. 



'X'HLS comprehensive treatise is the lirst English 

 -»■ monograph to deal exhaustively with 

 the fascinating but complex chemistry, of the 

 , natural organic colouring matters. The historical 

 ! aspect of the subject-matter and the scheme of 

 j classification are unfolded in the introduction, after 

 I which eighteen groups of natural dyes are 

 •■ described. The first chapter deals with the anthra- 

 quinone group, containing alizarin, the colour 

 principle of madder root, which shares with indigo 

 of the nitrogenous indole group the distinction of 

 being one of the dyes of an antiquity so remote 

 that it precedes the dawn of history. Although 

 the importance of alizarin and its synthetic deriva- 

 tives has overshadowed that of its other naturally 

 occurring congeners, yet it should not be over- 

 looked that the anthraquinone group contains also 

 cochineal, a colour principle originally obtained 

 from Mexico, and utilised in the ancient American 

 civilisations long before it became known to Euro- 

 peans. Lac and kermes, the Asiatic counterparts 

 of cochineal, also contain colour principles belong- 

 ing to the anthraquinone group. It is remarkable 

 that naphthalene, which figures so largely in the 

 production of synthetic dyes, is represented among 

 natural colouring matters only by the small naph- 

 thoquinone group. 



The majority of the natural yellow colouring 

 matters are derived from xanthone or flavone, and 

 much of our knowledge of these two groups is 

 derived from the researches of Prof. A. G. Perkin, 

 one of the authors, who has devoted himself for 

 many years to the study of this intricate branch 

 of organic chemistry. The flavone and flavanone 

 I groups have also received the attention of A band 

 of Irish workers under the guidance and inspira- 

 tion of Prof. Hugh Ryan. 



The researches of Willstiitter, carried out in the 

 generously endowed Kaiser Wilhelm Institute at 

 Dahlem, partly with the assistance of British and 

 American collaborators, including Dr. Everest, the 

 joint author of this treatise, have led to the elucida- 

 tion of the chemical nature of many colouring 

 matters of the y-pyran group. The anthocyan 

 pigments, present as glucosides in many flowers 

 and coloured fruits, form a comparatively large 

 class of natural colouring matters derived from 

 pelargonidin, cyanidin, and delphinidin. These 

 fundamental anthocyanidins are in all probability 

 produced from the yellow flavonol sap pigments 

 by a process of acid reduction. They are oxonium 

 compounds, which are generally isolated in the 

 form of their crystalline chlorides. These re- 

 searches, which have demonstrated the chemical 



NO. 



:587, VOL. 103] 



nature of the varied hues of the cornflower, salvia, 

 pansy, aster, chrysanthemum, peony, holly- 

 hock, and many other flowers, and of the colours 

 of the ripe cranberry, bilberry, and black grape, 

 are of the utmost scientific importance in extend- 

 ing our knowledge of the products of plant life. 



The dihydropyrane group includes haematein, 

 the colour principle of 1 igwood, the most important 

 natural dyewood, which is still extensively 

 employed by dyers. 



The chapter on the colouring matters of un- 

 known constitution shows that there is still ample 

 scope for patient study and systematic research 

 among the natural dyes. There is a special reason 

 now why these laudable efforts should be supported 

 to the fullest extent and with Governmental assist- 

 ance. Many of the plants yielding unclassified 

 dyes have a tropical or subtropical habitat, and 

 the fortunes of war are bringing these localities 

 more even than formerly under the control of the 

 Allied nations, to the exclusion of the Teutonic 

 States. It behoves the statesmen of the victorious 

 Allies to encourage to the fullest extent the work 

 of those trained observers who are prepared to 

 devote themselves to the study of these interesting 

 and possibly utilitarian problems. The treatise 

 under review, which presents a complete epitome 

 of the researches carried out on natural dyes, will 

 prove to be not only an indispensable work of 

 reference, but also a source of inspiration to any 

 scientific worker wishing to extend the boundaries 

 of our present knowledge of these colouring 

 matters. G. T. M. 



EDUCATION AND INDUSTRY. 

 Can We Compete? Germany's Assets in Finance, 

 Trade, Education, Consular Training, etc., and 

 a Proposed British War-cost Reduction Pro- 

 gramme. By G. E. Mappin. Pp. 159 + chart. 

 (London : Skeffington and Son, Ltd., n.d.) 

 Price 45. 6d. net. 



jV/TR. MAPPIN 'S book consists virtually of a 

 ^^^ number of essays on a wide variety of 

 subjects, which include technical universities, 

 town planning, land registration, the training of 

 women to become self-supporting, the reclamation 

 of peat bogs, etc. 



From his observations as a student in Germany, 

 Mr. Mappin describes how the different problems 

 are there dealt with, and, where a comparison is 

 possible with our methods, suggests the lines on 

 which our industry, commerce, and education 

 should be reorganised. The book lacks co-ordina- 

 tion between its various sections, and is written 

 in a sketchy and unconvincing way. In making 

 out a case in favour of certain proposals on 

 German lines, the author over-emphasises the pre- 

 vailing state of affairs in this country. Further, 

 he does not appear to be fully familiar with many 

 of the conditions he seeks to reform, advancement 

 in some respects having proceeded far beyond his 

 proposals. 



In common with many would-be reformers, Mr. 



O 



