May 9, 1889J 



NA TURE 



31 



the evidence for what is really a very beautiful theory 

 fails to carry conviction to us. Doubtless our " threshold 

 of sensibility" has gone wrong in some unaccountable 

 way, and we have not enough of the Subject on this 

 side of it to estimate the pearls of transcendentalism at 

 their true worth. To the true adept, the work will doubt- 

 less prove wholly acceptable, and the author may take 

 comfort in the reflection that " on this globe we serve an 

 ■end, the attainment of which cannot be hindered, though 

 all mankind conspired against it." 



OUR BOOK SHELF. 



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

 and C. Schorlemmcr, F.R S. Vol. III. The Chemistry 

 of the Hydrocarbons and their Derivatives ; or. Organic 

 Chemistry. Part V. (London : Macmillan and Co., 

 1889.) 



The present and fifth part of the "Treatise on Organic 

 Chemistry " is devoted to an account of the benzenoid 

 compounds containing eight or more than eight atoms of 

 carbon, and brings the subject down to the group of the 

 terpenes and camphors, including india-rubber and gutta- 

 percha. 



The various compounds are, as the title of the work 

 denotes, grouped about the hydrocarbons from which 

 they are derived. Thus we have the styrolene group, 

 the cumene group, the cymene group, and so on. 



The present instalment of the work also describes 

 numerous instances of the interesting class of benzenoid 

 compounds containing closed lateral chains in the ortho- 

 position, i.e. with the two ends of the chain attached to 

 -carbon atoms which in their turn are directly united 

 with one another. Such compounds are, for example, 

 the indoles, the indazoles, isatin, carbostyril, and cou- 

 marin. 



The subject of closed- chain compounds has of late 

 years possessed a peculiar fascination for organic 

 chemists, and the reason of this is not far to seek ; 

 for, apart from the fact that many of the closed- 

 chain derivatives of benzene, such as coumarin, isatin, 

 and indole, either occur in nature or are the imme- 

 diate derivatives of naturally occurring compounds, 

 many chemists believe that various important problems 

 in chemical statics may ultimately be solved by the 

 study of these compounds. At present chemists do 

 not altogether know why, for example, closed lateral 

 chains of carbon atoms should occur only in the ortho- 

 position, and never in the meta- or para position ; 

 why such closed lateral chains never contain less than 

 five or more than six carbon atoms ; and why it has 

 never been found possible to unite any single polyad atom 

 to two contiguous (ortho) carbon atoms in benzene, 

 whilst in paraffinoid compounds such a union may be 

 effected. But when these questions have been answered, 

 something will be known concerning the local distribu- 

 tion of the affinities of the ultimate atoms ; and mean- 

 while the ingenious hypothesis of Van 't Hoft' with regard 

 to the position of the affinities in the carbon atom is a 

 step in the right direction, and affords what is possibly 

 more than a merely provisional answer. 



The authors have also given a very full account of 

 Wallach's interesting researches on the terpenes, and 

 here, as elsewhere, the information is thoroughly up to 

 date. 



The instructive historical introductions prefixed to the 

 descriptions of important compounds and groups of com- 

 pounds, referred to in our notices of previous portions of 

 the work, are continued. 



Solutions 0/ the Examples in a Treatise on Algebra. By 

 Charles Smith, M.A. (London : Macmillan, 1889.) 



The value of such a book is great both to teachers and 

 students. The former, as we have often pointed out, have 

 scant leisure for working out the more elaborate ques- 

 tions which nowadays have place even in elementary 

 treatises, or scarcely care to refer to their notes, which are 

 never, unless they are exceptionally methodical men, to be 

 found when wanted ; the latter are, by means of such a 

 work as the one before us, in a great measure rendered 

 independent of outside aid. Though Mr. Smith's solutions 

 are marvels of compressed diction in many cases, they yet 

 are, we can certify from an extended examination of all parts 

 of the subject, expressed with all the clearness required. 

 In a few cases two solutions are given ; this is an advant- 

 age, for often we have found the second solution very sug- 

 gestive. We have, then, here an excellent corpus of 

 solutions of questions, which have been considered by 

 many competent judges to be well arranged and well 

 calculated to draw out a student's powers in this part of 

 mathematics. We have come across a few typographical 

 errors (there is one on the last page), but they are in most 

 cases easily detected on following out the solution. 



Applied Mechanics. By D. A. Low. (London : Blackie 

 and Son, 1889.) 



This is an excellent little text-book, treating of those parts 

 of the subject which the Science and Art Department 

 require for the elementary stage. There are, however, 

 specially marked articles which may be read by advanced 

 students. 



The author has taken, as the ground-work of the book, 

 the notes which he has used for many years in his classes 

 with much success. Much care has been taken with 

 those pages relating to mechanism. The diagrams are 

 especially good, and the descriptive portions accom- 

 panying them are clear and concise. A striking and most 

 useful feature will be found in the unusually large number 

 of examples following each chapter, typical examples also 

 being worked out between the articles. 



The last half-dozen chapters are devoted to the nature, 

 use, and strength of materials used for purposes of con- 

 struction, and the different kinds of stress to which they 

 may be subjected. The syllabus issued by the Depart- 

 ment for teachers in this subject, followed by the examina- 

 tion papers of recent years, is appended. The book is 

 one which can be recommended, and will no doubt be well 

 received by teachers and students alike. G. A. B. 



Northern Afghanistan. By Major C. E. Yate, C.S.I., 

 C.M.G. (Edinburgh and London: Blackwood, 1888.) 



In this volume the author has brought together a number of 

 letters written from the Afghan Boundary Commission, and 

 he explains that they are now published in a connected 

 form as a sequel to his brother Captain A. C. Yate's book, 

 entitled " England and Russia Face to Face in Asia." A 

 large part of the work relates chiefly to matters of political 

 interest ; but there are also excellent descriptions of the 

 various places which Major Yate visited, and of the 

 people with whom he came in contact. His account of 

 Herat and the shrines in the neighbourhood is particularly 

 good ; and Balkh, of which he gives a plan, he depicts 

 concisely and clearly. Of the desert from Andkhui to the 

 Oxus he says it is about as hot and wretched a country as 

 he ever saw. In this desert, wherever a few inches of 

 mud and water were left, he used to see the white-breasted 

 pintail sand-grouse coming to drink in small numbers ; 

 but with that exception he sav\f no sign of game. Lizards 

 of all sizes and colours were to be seen. A lizard, some 

 2 or 3 feet long — " of a yellowish colour with red stripes" 

 — seems to have especially attracted Major Yate's atten- 



