NA TURE 



[June 2, 1904 



pleted (so far as anything in a museum can be said 

 to be complete), while the Edentata, which was one 

 of the first groups taken in hand, had been arranged 

 at least a couple of years previously. 



Limitations of space forbid fuller notice, and we 

 may conclude by mentioning that while special 

 chapters are devoted to his favourite subjects, anthro- 

 pology and cetaceans, the three final chapters deal 

 with the later and closing scenes of Sir William's life. 

 Of four excellent portraits, those taken in his later 

 years serve to remind old friends of Flower's striking 

 personality. Bearing in mind the limitations already 

 mentioned, the author is decidedly to be congratulated 

 on the attractive manner in which he has laid before 

 the public the main features of a very interesting and 

 highly successful scientific career. R. L. 



THE IDENTIFICATION OF ORGANIC 

 COMPOUNDS. 

 A Method for the Identification of Pure Organic Com- 

 pounds. Vol. i. By S. P. Mulliken, Ph.D. Pp. 

 xii + 364. (New York: John Wiley and Sons; 

 London : Chapman and Hall, Ltd., 1904.) Price 

 2 re. net. 



THIS is the first of a series of volumes which are 

 intended to facilitate the identification of organic 

 substances. The scheme commonly, though not 

 invariably, adopted by organic chemists in this con- 

 nection is to determine the molecular formula of the 

 compound under investigation, and then to refer to 

 Richter's " Lexicon," in which all known organic 

 compounds are tabulated according to their molecular 

 formula. Further agreement is established by a com- 

 parison of physical and chemical properties. The 

 author considers that the difficult technique of conduct- 

 ing an ultimate organic analysis, upon which the 

 above system mainly depends, " is fully mastered only 

 by long practice," and that there is a shorter cut to 

 the same result. This short cut consists in finding, in 

 the first instance, to what class of compounds — hydro- 

 carbon, alcohol, aldehyde, acid, &c. — the substance 

 belongs, and, when this has been done, in determining 

 such simple physical characters as melting-point, boil- 

 ing-point, specific gravity, colour, smell, &c., which 

 will lead to its identification. It is therefore necessary 

 for purposes of reference that all the known organic 

 compounds should be grouped into separate classes. 

 This is what the author has done. In each class the 

 individual members are arranged in the order of in- 

 creasing boiling-point or melting-point. For example, 

 let us suppose that the substance, the identity of which 

 is required, proves to be an acid. All the knov/n organic 

 acids are divided into tables of liquid and solid acids, 

 and these again into categories, which are either 

 soluble or insoluble in water. Suppose that the acid 

 under investigation is a liquid which is soluble in 

 water. Having turned to the table containing the 

 liquid acids soluble in water, an examination of the 

 first column of boiling points will lead, perhaps, to the 

 discovery of one corresponding to the unknown acid. 

 Under this compound a series of characteristic re- 

 actions are described which will enable the investigator 

 NO. 1805, VOL 70] 



to fix the identity of his compound by means of a few 

 simple tests. 



There is very little that is new in the above method. 

 It is one which is adopted, consciously or otherwise, by 

 the majority of chemists, whether they possess the skill 

 requisite to conduct an ultimate organic analysis or 

 not. That carefully elaborated methods are at present 

 in use for determining the constitution of a substance 

 by chemical tests is clearly shown by the existence of 

 such a volume as Hans Mej'er's, which has been trans- 

 lated into English, and has already reached a second 

 edition. 



In point of fact, when a substance has been obtained 

 in a state of purity, its identification is as a rule not a 

 serious undertaking. The character of the substance 

 from which it is derived will usually furnish a clue 

 to its nature, and a few characteristic tests will soon 

 set the matter at rest. If the identification of a com- 

 pound is a crucial matter, few chemists would rest 

 content with anything less than a direct comparison 

 of the product with the known substance, for melting- 

 and boiling-points are apt to vary a little with the 

 aooaratus and form of thermometer employed, and 

 colour reactions do not always produce quite the same 

 tint unless the conditions of the experiment are 

 the same. 



It is the separation of a compound from a mixture 

 and its purification which make the greatest demands 

 on the skill and experience of a chemist. Compared 

 with this, an ultimate organic analysis and the 

 characterisation of a compound by chemical tests offer 

 little difficulty. 



There is no intention to disparage the labour which 

 has been expended on this work. The careful revision 

 of the reactions of many of the substances found in 

 the tables would entitle the book to grateful recog- 

 nition, in addition to which there is much useful and 

 practical information on the method of applying the 

 different reactions which every organic chemist will 

 appreciate. It would be incorrect, moreover, to state 

 that the tables will not serve the object for which they 

 have been compiled. The question is only whether 

 the object is worth the labour which it entails, seeing 

 that most of the information may be derived indirectly 

 from other sources. 



The biological system of classification of substances 

 into orders, genera and species cannot be commended. 

 It is unnecessary and undesirable. There is no 

 analogy in the application of these terms in the two 

 sciences, and their use may be misleading. Chemical 

 nomenclature still suffers in this country from such a 

 false analogy, when radicle was adopted in place of 

 radical. J. B. C. 



THE MIND OF THE CHILD. 



Educational Psychology. By Edward Thorndike, 

 -Adjunct Professor of Genetic Psychology in Teachers' 

 College, Columbia University. Pp. vii + 177. 

 (New York : Lemcke and Biichner, 1903.) 



THIS volume embodies the results of investigations 

 in which Prof. Thorndike has interested himself 

 and his pupils for some time past, applying the methods 



