64 



KNOWLEDGE. 



[Mabch 1, 1895. 



geographical distribution of the order Primates. To say 

 that the work forms a complete monograph of the order 

 would be to claim for it what everyone familiar with the 

 great advances in zoology during the past half century 

 would know to be untrue. But at the same time we have 

 no hesitation in saying that in these instructive handbooks 

 Dr. Forbes has given the public the benefit of his know- 

 ledge, with the result that, for conciseness and accuracy, 

 they together make an ideal text-book for the student and a 

 desirable work of reference for the well-informed reader. 

 Much remains to be done before our knowledge of the 

 Primates and their distribution will approach completion, 

 but that which has been accomplished is carefully and 

 cleverly epitomized. 



L'lowlland : A Studi/ of the Structure and Characters of 

 Clouds. By Eev. W.' Clement Ley, M.A., F.E. Met. Soc, 

 Pp. 208. (London: Edward Stanford, 1894.) Mr. Clement 

 Ley, than whom there is no higher English authority on 

 the forms of clouds, deserves the gratitude of meteorologists 

 for this most important addition to their literature. The 

 preparation of the book has involved an immense amount 

 of labour — so great, indeed, has been the toil, that it has 

 seriously impaired the author's health. There are several 

 reasons why the task should have been so difficult. Not 

 only are clouds vague and intangible objects, but the 

 causes which produce them are very complicated, and 

 meteorologists generally have eschewed the subject, 

 forgetting that the co-ordination and study of clouds would 

 probably lead to the discovery of important connections 

 between them and the weather. The author's main object 

 has been to help and interest individual observers in this 

 neglected branch of meteorology, and thus to aid the 

 growth of the science ; and, in our opinion, he has produced 

 a work so attractive in illustration, and untechnical in text, 

 that it cannot fail to extend the observation of "the 

 nurslings of the sky." The volume is enriched by a 

 number of reproductions of Mr. Arthur Clayden's beautiful 

 photographs, and a few coloured plates representing water- 

 colour sketches made by the author. It will certamly be 

 the cade mi'cwii of all students of nephology. 



A Handbook of the British jSlacro-Lepidoptera. By 

 Bertram Geo. Eye. Illustrated by Maud Horman-Fisher. 

 Vol. I., Part 1. (Ward and Foxlow ; 2s. 6d.) At length 

 we have before us coloured illustrations which are true to 

 Nature, and do not partake of the gaudy and highly- 

 coloured plates so often seen in works of this kind. The 

 first part of Mr. Eye's handbook, just published, does not, 

 it is true, deal with the insects most difficult to represent 

 in colours, but it contains enough of Miss Horman-Fisher's 

 excellent work to assure us that the high standard will be 

 maintained. The text, which chiefly deals with the meta- 

 morphoses and classification of the Lepidoptera, is concisely 

 and simply written. 



A Treatise on Ciwmisln/. By Su- H. Eoscoe, F.E.S., and 

 C. Schorlemmer, F.E.8. Vol. I., The Non-Metallic 

 Elements. (Macmillan & Co., 21s.) The new edition of | 

 the first volume of this valuable work contains con- J 

 siderable additions. The fresh matter in the introductory 

 part of the volume includes an account of the recent 

 researches on osmotic pressure, which have thrown so 

 much light on the nature of solution, and have led 

 to an important new method for determining the mole- 

 cular weight of a dissolved substance fi'om the lowering 

 of the freezing-point of the liquid in which it is 

 dissolved. When a dilute solution of sugar or other 

 crystallized substance is placed in a vessel whose walls 

 are formed of a " semi -permeable " material — i.e., one 

 which allows water to pass through it but prevents the 

 outward passage of the dissolved substance, the pressure 



inside the vessel is observed to rise. This pressure is 

 called the osmotic pressure, and is found to play the same 

 part in the theory of dilute solutions as gaseous pressure 

 in that of gases. The osmotic pressure depends on the 

 nature of the dissolved substance, the concentration of 

 the solution, and the temperature. The values given for 

 the atomic weights of the elements have been revised, 

 most of them being now represented by a smaller number, 

 the value for that of oxygen, from which many of the others 

 are derived, having been reduced in accordance with the 

 latest researches to 15-88 in place of 15-96, which was the 

 number given in the last edition of this work. 



A noticeable feature of this treatise is the representation 

 in the illustrations of the principal apparatus used in 

 chemical research, and in the technical applications of 

 chemistry. These are given with great clearness. In the 

 description of Pictet's process for hquefying gases, the 

 scientist's account, included in the former edition, of how 

 he obtained a steel-blue liquid jet of hydrogen and heard a 

 rattling haU of solid hydrogen particles, is omitted in this, 

 the author perhaps agreeing with the opinion expressed in 

 a French text book that M. Pictet must have been the 

 victim of an illusion. 



A further account is given of Moissan's recent interesting 

 work on the preparation of fluorine, which for so long 

 resisted all the efforts of chemists to isolate it. 



Care seems to have been taken to embody in this volume 

 a description of discoveries which have taken place since 

 the publication of the previous edition. For example, the 

 composition and properties of phosphorous oxide, as shown 

 in the experiments carried out a short time ago by Thorpe 

 and Sutton, are described. In place of the sentence " All 

 attempts to obtain the diamond artificially have as yet 

 been unsuccessful," which appeared in the edition published 

 six years ago, there is now a description of the interesting 

 method of Moissan, by which he has obtained artificial 

 diamonds by allowing carbon to crystalhze from solution 

 in iron under a high pressure. Amongst other additions 

 which might be mentioned is that of a few paragraphs on 

 the bacteriology of the air. Eeferences are given throughout 

 to some of the principal original memoirs, which will be 

 valuable to the student who wishes further information on 

 any point. 



The clearness of the printing is much conducive to 

 comfort in reading, and some misprints which occurred in 

 earlier editions have been corrected. With the new matter 

 embodied in the text this first part of the treatise forms a 

 full and reliable guide to the present state of knowledge of 

 the descriptive chemistry of the non-metallic elements. 



The Aeronautical Annual, 1895. Edited by James Means. 

 (Clarke & Co., Boston, Mass.) One dollar, post free. 

 This first annual, on the now recognized important subject 

 of navigating the air, is well worthy of perusal. Mr. Means 

 has wisely begun at the beginning of the records. Starting 

 with Leonardo da Vinci, who was born in 1452 and died 

 in 1519, the reader is favoured with a fine portrait of that 

 remarkable man, reproduced from a drawing in red chalk, 

 by himself, in the Boyal Library, Turin. Da Vinci was 

 certainly a man far in advance of his time. After selecting 

 some of his most important achievements, the editor 

 passes on to the writings of Sir George Cay'ley, 1809 ; 

 Walker, 1810 ; and Wenham, 1866. Then follow some 

 old curiosities, which are very amusing, though not of 

 much scientific value. Then, in succession, Darwin, 

 Henson, and others are mentioned. Notes on the biblio- 

 graphy of aeronautics, and references to Mr. Chanute's 

 literary labours, with valuable suggestions by the editor, 

 make it altogether a very readable book to all interested in 

 the navigation of the air. 



