NA TURE 



93 



THURSDAY, DECEMBER 5, 1878 



BO TANICAL CHEMISTR V 

 The Organic Constituents of Plants and Vegetable Sub- 

 stances and their Chemical Analysis. By Dr. G. €• 

 Wittstein. Authorised Translation from the German 

 Original, Enlarged with numerous Additions, by Baron 

 Ferd. von Mueller, F.R.S. (Melbourne : McCarron, 

 Bird and Co., 1878.) 



MANY who have been interested in botanical studies 

 may have been struck with the varied nature and 

 great number of chemical substances which are extracted 

 from plants and which in many cases impart to the 

 flowers their special and characteristic brilliant colours. 

 Up to the present time we have had in English no work 

 which has devoted itself specially to the systematic de- 

 scription of the nature and preparation of such substances ; 

 and the literature in connection with the subject, which 

 is by no means meagre, with accounts of investigations in 

 chemico-botanical research must be sought for in journals 

 generally devoted to purely chemical matter, and conse- 

 quently less likely to attract the attention or be available 

 for the use of the more general reader. 



With regard to other countries, however, this has not 

 been the case, as we find a considerable portion of the 

 work of Berzelius devoted to a consideration of the 

 bodies found in plants, and the " Anleitung zur Analyse 

 von Pflanzen und Pflanzentheilen " of Rochleder has 

 long been known both in Germany and elsewhere as 

 affording a good collection of the results of investigations 

 in vegetable chemistry up to the date of its publication 

 about the year 1858. 



During the last year, however, Baron Ferd. von 

 Mueller has brought forward a translation of Dr. G. 

 Wittstein' s "Anleitung zur chemischen Analyse von 

 Pflanzentheilen auf ihre organischen Bestandtheile," pub- 

 lished in 1 868, the value of which he has found in his 

 own researches, and which he has for some time wished 

 to render available for English readers. 



The present edition consists of two parts, each divided 

 into three divisions, which form as it were the chapters. 

 In the first part the"author has placed the consideration 

 of the proximate constituents of plants and vegetable 

 substances as far as hitherto known, together with their 

 properties and mode of extraction. His first intention in 

 the arrangement of this part, which is naturally the largest 

 portion of the work, was to adopt as far as possible a 

 systematic classification. From the imperfect state of 

 knowledge, however, as to the exact constitution of the 

 bodies, and from the fact also that some of the better 

 kno^\^l substances possess properties which might cause 

 them to appear in several groups if a classification de- 

 pending on natural properties was taken, he has finally 

 adopted an alphabetical order and has thus formed a 

 dictionary of so-called phytochemical substances. 



In the consideration of the individual substances Baron 

 von Mueller has evidently confined himself almost entirely 

 to their preparation from natural sources, and we have 

 therefore no description of the very interesting and re- 

 markable synthetical methods which are now employed 

 for the production of certain of these bodies. This may 

 Vol. XIX.— No. 475 



of course have been beyond the limit originally intended 

 by the present editor, but we should hope in the event of 

 future editions to have some mention made of the more 

 important recent investigations in this direction. The 

 two latter divisions of the first part are occupied with a 

 synopsis of the plants which yield the bodies previously 

 described and a list of the plants indicated, systematically 

 arranged in their different natural orders. The first of 

 these lists is remarkably good, as it gives not only the 

 names of the plants^ and those of the substances which 

 they yield, but also the various parts of the plant from 

 which these latter may be extracted. The want of such 

 a list has been felt, and this part of the work might have 

 been extended to rather wider limits ; in its present form, 

 however, it will still prove of considerable use. In 

 assigning chemical formulae to the substances described 

 in the first part of the book the editor has retained the 

 olderTorms of notation, but has introduced immediately 

 after the alphabetical list of bodies a table containing the 

 molecular weights of the compounds described according 

 to the modem views adopted by chemists ; this necessity 

 for two lists concerning the same thing introduces con- 

 fusion in the mind of the reader, and it would be well 

 therefore in a future edition to dispense altogether with 

 the older forms of molecular weights as they are little 

 used at the present day. 



The second part of the work is devoted to" the appa- 

 ratus and reagents necessary for phyto-chemical analysis 

 and to the description of a systematic course embracing 

 the different methods of procedure in conducting such 

 researches. In these analyses one of the most important 

 points is the proper extraction of the various ingredients 

 of the plant ; for this piirpose solvents such as ether, 

 alcohol, and ^vater are employed. As at first sight it might 

 appear immaterial in what order these solvents are to te 

 used the author points out the importance of employing 

 them in the following order : first ether, then alcohol, and 

 finally water, and by this means preventing such bodies 

 as wax or fat which are completely and entirely dissolved 

 by ether, from passing also into the alcoholic extract in 

 w^hich they are only partially soluble. This also would 

 apply to the extraction of certain of the alkaloids, as in 

 their case partial separation may be carried out in their 

 extraction by the different solvents. 



It is to be regretted that the more modern names 

 and atomic weights are not employed in this portion of 

 the work, and also in the description of the preparation 

 of reagents ; thus, we find the molecular weight of 

 calcium carbonate given as 625, and that of calcium 

 oxalate as 1025 : at the present time the use of such, 

 numbers tends greatly to confuse the student. 



At the end of the work Baron von Mueller has arranged 

 some useful tables, comprehending the comparison of 

 Centigrade and Fahrenheit thermometric scales, the 

 specific gravity of alcohol of different percentages by 

 weight and by volume, the relation between cubic centi- 

 metres and cubic inches, between litres and fluid ounces, 

 and a table of the atomic and molecular weights of the 

 principal elementary bodies. 



There can be little doubt that this work supplies 

 a great want in chemical and botanical literature, but 

 there is still room both for the farther elaboration of 

 the matter discussed, and, in certain cases, for some 



