December 8, 1892] 



NATURE 



125 



which should follow Experiment 112 (Preparation of Ethyl 

 Nitrite) have been moved on by a whole page, and made 

 to follow Experiment 115 (Preparation of Nitro-ethane). 

 The utterly bewildering effect of this jumble, which is en- 

 hanced by the unexpected re-entrance of the subject of 

 nitro-ethane in the middle of a paragraph a little later on, 

 cannot be realized without reading the passage. 



The work is intended to combine practical with theo- 

 retical instruction. The selection of experiments is, on 

 the whole, judicious, and the practical directions are gener- 

 ally good. This is not to be wondered at, as the author 

 has evidently, in these points, followed pretty closely 

 Prof. Emerson Reynolds's "Experimental Chemistry," 

 even to such details as the substitution of a tin oil-can for 

 a distilling flask (p. 99), or a peculiarity in the bending of 

 a tube (p. 74), and to the reproduction of some of the 

 illustrations -in every case without acknowledgment- 

 Prof. Reynolds is not, however, responsible for the illus- 

 tration on p. 17, in which the distillate from a Liebig's 

 condenser is represented as falling from a considerable 

 height into a flask placed below. 



It is not true that (p. 12) "every organic compound 

 containing nitrogen will, when fused with metallic sodium, 

 convert the latter into sodium cyanide." Diazo-com- 

 pounds do not yield any cyanide ; and compounds 

 containing sulphur as well as nitrogen form thiocyanate. 

 Nor is heating a cyanide with excess of concentrated 

 sulphuric acid (p. 76) a method of distinguishing it from 

 a formate. 



The author's style is occasionally slovenly, and some- 

 times wor^e : " Observe how the fact that oxalic acid so 

 readily split up into CO, CO^ and H.p support {sic) this 

 graphic formula for it " (p. 117). 



On the whole, we suspect that teachers will prefer a 

 text-book which calls for fewer marginal corrections. 



OUR BOOK SHELF. 

 An Introduction to the Study of Botany, with a special 

 chapter on some Australian Naturcil Orders. By 

 Arthur Dendy, D.Sc, and A. H. S. Lucas, M.A. Small 

 8vo, 272 pages with about 30 pages of woodcuts. 

 (Melbourne and London : Melville, Mullen and Slade, 

 1892.) 



The authors of this little work are both teachers of 

 Natural Science in the University of Melbourne and it 

 is specially intended for the use of students in Australia. 

 With this object in view it would have been better per- 

 haps to have selected common Austr.ilian types to illus- 

 trate the life history of the great divisions of the vegetable 

 kingdom ; but Pinus is taken as a representative of 

 gymnosperms and F/V/a of angiosperms. Whether these 

 plants are both easily procurable in Australia we are 

 unable to say, but even in that case it would have been 

 better to have taken native plants Possibly the prepar- 

 ation of illustrations may have influenced the authors, for 

 they are largely, in the first part, " modified," " simplified," 

 or " adapted " figures from well known books, or they are 

 simply copied. Taken as a whole, we do not doubt that 

 this primer will prove useful to students, but it needs 

 much revision to make it what it ought to be. Here and 

 there, where we have tested it, we have found serious 

 shortcomings. Take for example the account of the 

 divisions of the vascular cryptogams. 



" I. Filicinea. — These are the ferns which constitute 

 a very large and interesting subdivision. The full account 

 already given of the common bracken renders a detailed 



NO. 1206, VOL. 47] 



description unnecessary in this place. There are two 

 principal subdivisions of the Fi/icinecE ; the homosporous, 

 which produce only one kind of spore, and the hetero- 

 sporous, which produce large megaspores and small 

 microspores. The former include all the ordinary ferns 

 and are again subdivided into six 'families,' of which 

 the Polypodiaceaeare the best known and most abundant, 

 including most of the common ferns, such as Pteris." 



One would have expected a word or two respecting the 

 heterosporous group— the Rliizocarpece, with some mention 

 of Marsilea, so memorable in the history of Australian 

 exploration ; but the authors seem to have come to grief 

 between the older and newer classifications of vascular 

 cryptogams, for in another place (p. 90) we read of 

 " heterosporous ferns." The definition of the Equisetinea 

 contains no reference to the spores ; and the description 

 of the LycopodinecB contains no information at all. It 

 runs thus : " This group includes the club-mosses 

 {Lycopodium) and the beautiful Selaginella, a plant 

 frequently grown in conservatories for decorative pur- 

 poses. They are all of rather small size, and are popularly 

 spoken of as " mosses " owing to the general appear- 

 ance of the plant with its numerous very small leaves." 



Comment on such a description would be superfluous. 

 In the classification of the cellular cryptogams, lichens 

 are altogether left out, and are apparently not mentioned 

 anywhere. In fact the same incompleteness and inexact- 

 ness pervades the book, which opens with a eulogistic 

 prelace by W. Baldwin Spencer, Professor of Biology 

 in the University of Melbourne. W. B. H. 



A German Science Reader. (Modern German Series.) 

 Compiled by Francis Jones, F.R.S.E. (London: 

 Percival and Co., 1892.) 



The idea of introducing to English readers extracts 

 from the works of many well-known German scientific 

 authorities will be thoroughly welcomed. The author 

 has brought together sixteen very interesting articles on 

 several branches of science, supplemented with notes, in 

 which difficult passages are translated, and a glossary of 

 the technical terms not usually found in dictionaries. 

 Among the articles we may mention, Electric Telegraphs 

 by Bernstein ; Ice and Snow by Kantz ; Air by Miilltr ; 

 Aniline Dyes by Kekul^ ; Spectrum Analysis by 

 Kirchhoff and Bunsen, &c. W. 



More About Wild Nature. By Mrs. Bright wan. (Lon- 

 don : T. Fisher Unwin, 1892.) 

 Mrs. Brightwen's book on " Wild Nature Won by 

 Kindness " was so widely appreciated that she has been 

 encouraged to prepare a second volume of the same 

 general character. It speaks well for her knowledge of 

 animals, and for her interest in their habits, that the 

 new sketches are written in as fresh and bright a style 

 as if she had never before occupied herself with the 

 mass of subjects with-which she deals. She is a careful 

 and accurate observer, and all readers who care for 

 natural history will find much to please them in the facts 

 and impressions she records. The author's illustrations 

 add greatly to the charm of the text. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents . Neither can he undertakr 

 to return^ or to correspond -uilh the writers of rejecteil 

 manuscripts intended or this for \xny other part of Nature. 

 No notice is taken of anonymous communications.^ 



Arborescent Frost Patterns. 



On Sunday last, December 4, I observed a curious pbeno 

 menon, which I do not remember having ever !-eeri before in 

 the .streets of London. Along the Euston Koad, the Marylebone 



