March 31, 1892] 



NATURE 



509 



OUR BOOK SHELF. 



A Treatise on Chemistry. By Sir H. E. Roscoe, F.R.S., 



and C. Schorlemmer, F.R.S. Vol. III. "The 



Chemistry of the Hydrocarbons and their Derivatives ; 



or, Organic Chemistry." Part VI. (London : Mac- 



miilan and Co., 1892.) 

 The present section of this well-known work deals with 

 the derivatives of naphthalene and the allied hydrocarbons 

 — phenanthrene, chrysene, &c. ; also with the compounds 

 containing two or more benzene nuclei directly united, 

 such as diphenyl. 



The extraordinary expansion which this particular 

 branch of organic chemistry has undergone during the 

 last fifteen years is due in part doubtless to the fascina- 

 tion of the various problems of constitution which these 

 comp'Hmds offer, and to the well-founded assurance 

 that Kekulc's benzene theory, which had thrown so much 

 light on the subject of benzene itself and its more im- 

 mediate derivatives, would prove an equally trustworthy 

 guide in the case of the more complex hydrocarbons of 

 the same class. But it is doing no injustice to pure 

 chemists to say that a great part of this expansion is 

 attributable to the fact that numerous valuable practical 

 applications have been found for some of the compounds 

 in question. 



In 1876, when Wurtz published his " Progr5s de I'lndus- 

 trie des Matit;res Colorantes Artificielles, " the colouring- 

 matters derived from naphthalene might be counted on 

 the fingers of one hand, and not more than two of these — 

 Magdaia red and Manchester yellow — were really manu- 

 factured ; whilst from diphenyl not a single dye-stuff had 

 been prepared. At the present moment, only a specialist 

 in this branch could estimate, even approximately, the 

 number of the naphthalene dyes ; and within the last few 

 years another important class of dyes, possessing the 

 hitherto unknown property of dyeing cotton without a 

 mordant, has been discovered among the derivatives of 

 diphenyl. 



The industrial source of much of our knowledge in this 

 branch of chemistry is clearly shown in the fact that in the 

 work now before us the references are not confined to the 

 familiar scientific periodicals, but extend to the patent 

 literature of various countries and to works like Schultz's 

 " Steinkohlenlheer " and F>iedlander's " Theerfarben." 

 Without going into unnecessary detail, the authors suc- 

 ceed in giving all which it is necessary for the student of 

 organic chemistry to know regarding these matters. 



The questions of constitution are treated very fully and 

 clearly. The reader who wishes to gain an idea of what 

 organic chemists have accomplished, in the solution of 

 problems which but a few years ago would have been 

 regarded as utterly beyond the scope of rational investiga- 

 tion, cannot do better than study carefully the chapter on 

 the constitution of the naphthalene derivatives. 



The authors continue to follow their excellent practice 

 of giving interesting historical details by way of introduc- 

 tion to the study of the more important compounds. 



77/1? Oak : a Popular Introduction to Forest Botany. By 

 H. Marshall Ward, M.A., F.R.S., P'.L.S. " Modern 

 .Science Series," edited by Sir John Lubbock, Bart., 

 M.P. 171 pages, and Index, 2 Plates, and 51 Woodcuts. 

 (London : Kegan Paul, Trench, Triibner, and Co., 

 Ltd., 1892.) 



This little book fills a distinct gap, as it is the first time 

 that a prirger intended specially for students of forestry 

 has been issued in England. Prof. Marshall Ward has 

 been for many years the Lecturer on Botanv at the Royal 

 Indian Engineering College at Cooper's Hill, and there- 

 fore understands thoroughly what is required. He has 

 followed for his plan the taking of a single tree— the oak — 



NO. I I 70, VOL. 45J 



and dealing with it exhaustively. After a general intro- 

 duction, he deals first with the acorn and its germina- 

 tion, describing fully the embryo and its epidermis, the 

 vascular bundles of the former and its cells, and the 

 character of their contents. He tells us that two years 

 elapse before the supply of food stored up in the two 

 thick cotyledons is exhausted, and it is not until the 

 tree is from sixty to a hundred years old that good seeds 

 are obtained from it. Then he describes the seedling 

 and young plant — first the root and its tissues, and then 

 the stem, buds, and leaves, and their microscopic struc- 

 ture. Then he turns to the full-grown tree, and describes 

 its root-system, shoot-system, inflorescence, flowers, fruit, 

 and seed. Next he deals with the timber of the oak, its 

 structure, and technological peculiarities. Then he treats 

 of the cultivation of the tree, and the injuries and diseases 

 to which it is liable from the attacks of insects and fungi. 

 He concludes with a short chapter on the relationships 

 of the oaks and their distribution in space and time. 

 The genus is characterized by the cnpule, in which 

 the acorn is inclosed, which represents a one-flowered 

 involucre. There are three cells in the ovary, and 

 two ovules in each ; but nearly always two of the 

 cells and five of the ovules are obliterated before the 

 seed is perfected. About 300 species of the genus 

 Quercus are known. It is spread universally through 

 the north temperate zone. Prof. M. Ward is mistaken 

 in supposing there are no oaks in South America. Two 

 species have long been known in the Northern Andes — 

 Quercus tolimensis and Quercus Humboldtii — both of 

 which are described and figured in Humboldt and Bon- 

 pland's " Plantes Equinoxiales." There are nearly sixty 

 species in India, and it is there that we get the genus 

 connected with the other Cupulifera; by passing through 

 Castanopsis into Castanea. The oaks go back to the 

 Cretaceous period, and a large number of fossil forms 

 are known. Their delimitation into species is very diffi- 

 cult. In Britain we have only a single species, Quercus 

 Robur, with two sub species Q. pedtmculata and sessili- 

 Jlora, well enough marked in their extreme forms, but 

 passing into one another by gradual stages of transition, 

 which constitute what has been called Quercus inter- 

 media. The book is clear and well arranged, and will 

 be found thoroughly adapted to fulfil its purpose, and is 

 illustrated by a large number of excellent figures, some of 

 which are original and some borrowed from German 

 text-books. J. G. B. 



The Elements of Plane Trigonometry . By R. Levett and 

 C. Davison. (London: Macmillan, 1892.) 



Though the spirit of De Morgan's writings pervades 

 these " Elements," there is ample evidence that the writers 

 have taken an immense amount of pains in bringing 

 them fully up to date. We have long given up looking 

 for originality in a treatise on trigonometry ; indeed, in a 

 text-book for use in schools such a feature is hardly 

 desirable, but there are not wanting here many novel 

 features in the matter introduced and in its mode of treat- 

 ment. De Morgan's influence is shown " in the use of the 

 negative hypotenuse in defining the ratios, in the more 

 definite meaning assigned to the notation for inverse 

 functions, the manner in which the addition formulas are 

 extended to any number of variables, the geometrical 

 treatment of the hyperbolic function and of complex 

 numbers, and in the two-fold generalization of a logarithm 

 to a given base." Another work to which the authors are 

 indebted in Parts II. and III. is Prof. Chrystal's masterly 

 treatise on algebra. In fact, they are au courant with 

 whatever has recently been written bearing in any way 

 upon their subject-matter. 



The book is divided, like ancient Gaul, into three parts. 

 The first tieats of arithmetical quantity, in five 



