76 



NA rURE 



[May 24, 1900 



we should have liked a well-considered opinion from the 

 authors ! 



In an area like the Shetlands the great interest, from a 

 faunistic point of view, centres on the birds ; and among 

 these the great skua holds the foremost place, since its 

 only British breeding-stations are on these islands. So 

 much has been of late years written on this subject, both 

 in newspapers and in ornithological journals, that it is 

 one with which the public are tolerably well acquainted. 

 Nevertheless, the account given by the authors of the 

 almost complete extermination of this fine species, and 

 its subsequent rehabilitation by the efforts of various 

 members of the Edmonston family and Mr. Scott, of 

 Melby, will be read with interest, and forms a concise 

 summary of the whole affair. We should, however, like 

 to know more with regard to the meaning of the statement 

 that " protection for the skuas implies some measure of 

 protection also for the gulls ; but unless the latter greatly 

 increase, the former cannot be expected to do so." 



Some interest also attaches to the specimen of the 

 collared pratincole killed by Bullock in 18 12, as being 

 the only example of the species hitherto shot in North 

 Britain. In the fourth edition of "Yarrell" the skin is 

 stated to be in the British Museum, but the investigations 

 of the authors fail to confirm this statement. 



Greater attention is, however, merited by the account 

 of the nesting of the storm petrel, which sometimes lays 

 its eggs among large stones on the shore, and in other 

 cases selects deserted rabbit-burrows for its home. The 

 crofters, knowing the value set on the eggs of this bird 

 by collectors, and being likewise extremely partial to 

 young petrels as a bojtne boiicke, are extremely reluctant 

 to indicate the rabbit-holes in which the birds nest to 

 strangers. 



To many it will come as a surprise to learn that ravens 

 are still common in the islands ; so numerous, indeed, as 

 in certain districts to prove very destructive to the 

 poultry and stock, on which account war is waged 

 against them by the crofters. In contrast to the abund- 

 ance of these birds is the scarcity of rooks, which are, 

 indeed, little more than casual visitors to the islands. 



The weakest point about the book is undoubtedly, as 

 the authors themselves are fain to confess, the section on 

 fishes, the classification followed being altogether obso- 

 lete and discredited. R. L. 



PHYSICAL CHEMISTRY. 

 Introduction to Physical Chemistry. By James Walker, 



D.Sc, Ph.D. Pp. X + 332. (London : Macmillan 



and Co., Ltd.) 

 T T is now nearly ten years since Prof Walker placed 

 -*- English students under obligation by his admirable 

 translation of Ostwald's "Outlines of General Chemistry." 

 Since that time " little Ostwald " has been the source 

 from which most students have taken their first draught 

 of information about physical chemistry in its modern 

 form. The phrases and paraphrases of the book, the 

 diagrams, the perpetual motions " which are impossible " 

 have become almost painfully familiar to the examiner. 

 The present writer is one of those who believe that 

 NO. 1595. VOL. 62J 



Ostwald's book has been of the highest service to 

 chemistry. At the same time, it must be admitted that 

 it is one to be used with care. There is an illusory 

 appearance of simplicity about it, and if care be not 

 taken the use of the book is eminently calculated to lead 

 to a learned smattering. It is, in fact, a book which 

 forms the summary of a course of instruction, and for 

 beginners it must be supplemented by an extended 

 commentary by an experienced teacher. 



These observations arise inevitably in connection with 

 Prof Walker's new book, which, in size, appearance and 

 typography, as well as in its topics, bears so striking a 

 resemblance toOstv/ald's "Outlines." The first question 

 that the reader will ask is — Where lies the difference 

 between the two books ? This question is soon answered 

 as one reads ; Prof. Walker's book is more limited in 

 range and incomparably simpler. To quote the author's 

 words, it " makes no pretension to give a complete or 

 even systematic survey of physical chemistry" ; the aim 

 is to give a full discussion of some of the chief principles 

 of modern physical chemistry, and to show their appli- 

 cation to ordinary laboratory chemistry. 



Dr. Walker has achieved his purpose in a most satis- 

 factory manner, and has produced a book which will be 

 a real boon to students of physical chemistry. He writes 

 with the knowledge of a specialist and the experience 

 of a teacher, and it is very striking to any one who 

 knows the difficulties of students to see how perfectly 

 Dr. Walker appreciates them. Not less striking are 

 the expository power and resourcefulness with which the 

 difficulties are handled. Whilst the whole book is clear, 

 readable, and abreast of the times, some chapters deserve 

 special attention. The one on chemical equations is 

 amongst these. It gives a rational account of the art of 

 constructing chemical equations by dissection and summa- 

 tion, a subject which has been strangely neglected by 

 text-book writers. The chapter on fusion and solidifica- 

 tion is made very clear by a thorough discussion of the 

 mutual relations of salt, ice and water. The wide 

 generalisation, or group of generalisations known as the 

 Phase Rule, is expounded within reasonable limits. 

 Hitherto there has been nothing concise on this subject 

 in the English language. The chapters relating to the 

 modern theories of solution are, it need scarcely be said, 

 written with fulness of knowledge and in the spirit of 

 a true believer in the doctrine of electrolytic dissociation^ 

 Chemical dynamics is treated succinctly, and admirably 

 illustrated by examples. There is a distinct gain h^re 

 in departing from the strict historical development of the 

 subject, which is apt to confuse beginners by the series 

 of fresh starts which it involves. The concluding chapter 

 on thermodynamical proofs is made as clear as it well 

 could be. At the end of each chapter references are 

 given to original articles which have appeared in English 

 journals and to English books. The list of these is 

 quite gratifying, but the wisdom of confining the refer- 

 ences to English publications seems questionable. The 

 extraordinary backwardness of students m acquiring a 

 reading knowledge of German is condoned by such a 

 restriction ; and, besides this, it would have been a 

 service to many students who have some knowledge of 

 the language if Dr. Walker had helped them to select 



