52 



NA TURE 



[May 1 6, 1901 



The first part deals with the history of the periodic law 

 and the experimental evidence for periodic variation of pro- 

 perties with atomic weight, and in many cases information 

 is given in so condensed a form that it must be well- 

 nigh unintelligible to those whom the author has avowedly 

 sought to benefit, students "who may not have either 

 time or opportunity to refer to the original literature." 

 This is particularly the case in the portions which deal 

 with various attempts to formulate numerical relations 

 between the atomic weights. 



In the second part of the book the author seeks to 

 establish the theses (i) that "the elements have a fixed, 

 definite structure," (2) that "the elements are complexes 

 of some primary material," and (3) that this primary 

 material is hydrogen. Dealing with the first of these, 

 the author gives a sketch of the evidence to be derived 

 from stereo-chemistry which is so short that it amounts 

 to little more than a series of references, but which is 

 useful so far as it goes. The inference that the elements 

 in any one group of MendeldefPs table should all have 

 the same shaped atom is somewhat sweeping, but is op- 

 portunely supported by the recent work of Messrs. Rope 

 and Peachey on optically active tin compounds. 



As to the second, the arguments which have been 

 advanced in support of it are fairly well presented, but 

 the author misses altogether the point that the "meta 

 elements" of Crookes supply an essential link in the chain 

 of reasoning by which it is possible to reconcile the 

 discontinuity implied in the atomic theory and the 

 periodic law with the continuity predicated in the 

 hypothesis of protyle. 



In support of the third proposition, that protyle and 

 hydrogen are one, the author adduces several well-known 

 arguments, many of which, particularly those based on 

 stellar spectroscopy, are fairly well stated and of acknow- 

 ledged cogency. But his answer to the obvious difficulty 

 that the atomic weights are not whole multiples of that 

 of hydrogen is, though not unfamiliar, decidedly unsatis- 

 factory. That the third law of motion may be valid only 

 where molar masses are concerned is, of course, a legiti- 

 mate suggestion, but it is a suggestion in support of 

 which no fact save the difficulty under discussion can at 

 present be adduced. It is surely as reasonable to regard 

 that difficulty as fatal to the hypothesis that hydrogen is 

 protyle as to find in it a reason for doubting the universal 

 applicability of the third law of motion. ; 



The author, moreover, minimises in an extraordinary 

 way the remarkable evidence which has been accumu- 

 lated through the study of ions produced in gases by the 

 action of Rontgen rays, Becquerel rays and ultraviolet 

 light. "The portion of this book dealing with chemical 

 evolution was," we are told, "submitted to Sir Norman 

 Lockyer," and some of the notes which he made upon it 

 are prefixed to the volume. In them attention is drawn, 

 more than once, to the importance of this work on gaseous 

 ions in relation to the problem under discussion. The 

 author does, it is true, add to these notes a brief abstract of 

 one of Prof. J. J. Thomson's papers. But the matter is far 

 too important to be thus disposed of in a prefatory note. 

 The fact that the negative ion in gases has a mass which 

 is very small compared with that of an atom of hydrogen 

 is well established, not only by the researches which the 

 author quotes, but by other and later work of Prof. 

 NO. 1646, VOL. 64] 



Thomson on the negatively charged particles gi\ en off 

 when ultraviolet light falls on a zinc plate, and also by 

 the experiments of MM. Becquerel and Curie on the 

 radiations emitted by radium. The conclusions to be 

 drawn from these researches, while they are in full accord 

 with the view that the elementary atoms of the chemist 

 are themselves complex aggregates of yet smaller par- 

 ticles, require that these particles should be of an order of 

 magnitude so far inferior to that of a hydrogen atom that 

 they cannot fairly be described as "hydrogen " at all. 



If, as may be expected, a second edition of the work is 

 called for, it is to be hoped that the author will take the 

 opportunity of incorporating these results, and with them 

 the still later work of Prof. Townsend on the varia- 

 tions of conductivity in rarefied gases, the results of 

 which also emphasise in a remarkable way the e.xtreme 

 smallness of the negative ions. 



In conclusion, it must be said that the author has 

 occasionally suffered unduly at the hands of his printer. 

 There are a number of ordinary misprints which might be 

 expected in a work of the kind, but a worse piece of 

 printing than that of the numerical expressions illustrating 

 the summary of Dr. Dulk's paper (on p. 71) it would 

 surely be difficult to find. A. F. W. 



OUR BOOK SHELF. 



Dcr Gesang der Vogel. Von Dr. Valentin Hacker. 

 Pp. 1-H02. (Jena: Gustav Fischer, 1900.) 



This is an exceedingly interesting and useful contribu- 

 tion, and may be regarded as perhaps the most accurate 

 and complete summary of this subject extant. 



The author devotes the opening pages of his work to 

 purely anatomical details, illustrated by numerous text- 

 cuts representing voice organs of the passerine type. He 

 introduces, for purposes of comparison, a short descrip- 

 tion and a figure of the tracheo-bronchial region of the 

 reptile, the tortoise being selected as the most suitable. 



The second chapter opens with a reminder that the 

 variety of tone and range of vocal power depends largely 

 on the modification of the upper ends of the bronchial 

 tubes and the lower end of the syrinx. This is supported 

 by a brief survey of the simpler types of syrinx ending in 

 the very perfect voice organ of the Passeres, with its 

 complicated muscular system and fusion of tracheal rings 

 — the tracheo-bronchial syrinx. 



That muscular development, however, does not neces- 

 sarily imply great powers of song is, as he rightly remarks, 

 well shown by the fact that the muscles of the raven and 

 thrush are precisely the same in number and distribution. 

 Furthermore, the muscular system of the raven is the 

 better developed of the two ; but there can be no doubt, 

 in spite of this, which is the better songster ! Again, 

 though the songs of the true Passeres are extremely 

 varied, yet there is no perceptible variation in the 

 muscular system ; indeed, such variation is obviously 

 unnecessary, for the same bird may, and does, repeat the 

 song of numerous other birds as proficiently as the birds 

 to whom the songs rightly belong. 



It is interesting to note that Dr. Hacker seems to have 

 shown that sexual distinctions in the syrinx can undoubt- 

 edly be demonstrated, that of the female being always 

 more feebly developed. This being the case, one would 

 scarcely have supposed that the female, as in the case of 

 the bullfinch, for instance, would sing as well as the 

 male, but so it is. ■ 



Castration acts directly on the syrinx, much as on the 

 horns of deer, for instance ; the capon having a syrmx 



