April 25, I 



NATURE 



60 ] 



numerous other subjects supposed to be included within 

 the domain of natural hygiene. The second part of the 

 book is devoted to what are called the sanitary proper- 

 ties of Eucalyptus-trees, of pine-trees, and of camphor 

 forests. At first sight the general character of the work 

 impresses the reader favourably. He is disposed to 

 read it for the sake of acquiring information on subjects 

 which force themselves on public notice in every large 

 town. These are : the purification of water ; the relations 

 existing between micro-organic life and the so-called 

 infectious or contagious diseases ; the measures to be 

 adopted for the disposal and treatment of sewage, and 

 the relative value of certain antiseptics and disinfectants. 

 The author devotes to these subjects numerous pages of 

 information more or less relevant to them. At p. 217, 

 however, the author arrives at the matured conclusion 

 that " the only disinfectant which, while possessing all 

 these characters, also acts upon anaerobic and aerobic 

 forms of life alike, of which I have knowledge, is that 



known as , for the existence of which I am proud 



to take credit." Besides this disinfectant, there is an 

 equally good " fluid," an equally good " oil," and an 

 equally good " powder," for all of which, no doubt, the 

 writer has also pride in taking credit. There are in all 

 some thirty references to these specifics. 



The concluding chapters, in which Eucalyptus globulus 

 and other species of Australian gum-trees are credited 

 with wonderful powers as " fever-destroying trees " on 

 account of "the aromatic vapours which emanate from 

 the trees, and the preservative powers of the branches 

 and leaves which fall on the ground," repeat a well- 

 known but scarcely established doctrine of hygienists. It 

 is probable that any fast-growing tree, suited for swampy 

 districts, would produce exactly the same or similar 

 results. But, granted for the moment that the essential 

 oil given off in a vaporous condition from Eucalyptus or 

 pine-trees is disinfectant in character and conducive to 

 health, we fail entirely to see how this can apply also 

 to camphor-trees. Yet we are told that "the natural 

 history of camphor forests affords us another and remark- 

 able feature of Nature's hygiene ; . . . that atmo- 

 spheric oxygen is constantly being absorbed by the 

 essential oils that are continuously evolved into the air, 

 and this simple process gives rise to the production of 

 a number of active chemical substances, including per- 

 oxide of hydrogen and soluble camphor, all of which 

 purify the air and enhance the healthful influences of the 

 climate." Those who are at all acquainted with camphor- 

 trees will admit that this is a very fanciful picture indeed. 

 In common with most members of the Laurinece, the 

 emanations from camphor-trees are neither agreeable nor 

 balsamic. The author brings no evidence whatever to 

 establish his position, and we beg leave to doubt the 

 healthful influences- of camphor-trees on the grounds 

 stated until we have something more tangible than the 

 mere assertion of the author of this work. 



OUR BOOK SHELF. 

 Elementary Inorganic Chemistry. By A. Humboldt 

 Sexton, F.R.S.E., F.I.C., F.C.S. (London : Blackie 

 and Son, 1889.) 



The chief part of this manual of 320 pages is specially 

 prepared for students who are guided by the elementary 



division of the Syllabus of the Department of Science and 

 Art. In addition there are twenty-five pages about the 

 metals and their compounds, a chapter of nine pages on 

 what is called " Organic Chemistry," twenty-three pages 

 of " Experimental Illustrations," a chapter on " Chemical 

 Arithmetic," a series of questions, an " Elementary 

 Course of Qualitative Analysis " occupying thirty pages, 

 and a few less important matters. 



The main part of the book is pretty much what one is 

 accustomed to in elementary treatises : it is clear and 

 calculated to be useful ; but the chapters on the metals 

 and on organic chemistry are obviously meagre to a 

 degree. The organic part deals with those substances 

 mentioned in the alternative course of the above-men- 

 tioned Syllabus, but it would have been much better for 

 the book and the students who use it if these few pages 

 had been omitted. The analytical course refers to eight 

 metals and four acids. It is not stated why these sub- 

 stances are specially favoured. 



It is a pity that those who write on a subject like 

 elementary inorganic chemistrj', which has been so prolific 

 of text-books that practically speaking no exertion or 

 thought is needed in the selection of topics or the manner 

 of their treatment, should not more often concentrate a 

 little attention upon the exactness of their expressions. 

 The statement, for example, that " If hydrogen and oxygen 

 or air be mixed, and a light be applied, they will com- 

 bine with a violent explosion," is open to much censure. 

 Do hydrogen and air ever combine .' Will a mixture of 

 hydrogen and oxygen as a matter of course explode 

 under the circumstances described ? Again, the statement 

 that " Potassium and sodium only expel one-half of the 

 H from water" may be legitimately described as untrue. 

 The equation " Na + H0SO4 = NaHSO^ + H " is more 

 likely to deceive thm instruct the student. These are 

 not isolated examples. 



A Class-book of Geography. By C. B. Clarke, F.R.S. 

 (London : Macmillan and Co., 1889.) 



This is a new and revised edition of Mr. Clarke's well- 

 known class-book of geography, which was first published 

 in 1878. The populations of towns have been brought 

 up to date, as also the political geography of Egypt, 

 Turkey, &c. The names of places which have lately 

 become of importance in consequence of commercial 

 enterprises, such as Baku, have also been added. Perhaps 

 the most important addition, however, is a chapter on 

 astronomic geography, which is very clear, though neces- 

 sarily not very detailed. An excellent outline of charto- 

 graphy has also been added. The particulars given 

 relating to each country are of the usual character. They 

 include an historical sketch of each country, manufactures, 

 minerals, animals and plants, languages, religions, and 

 forms of government. At the end of each section is a 

 condensed statement of the principal features of each 

 country. A short description of the different races of 

 animals might have been given with advantage, as at 

 present the student can only gatner the meanings of such 

 terms as " Pachyderms " and " Chiroptera" from the ex- 

 amples quoted. The omission of the word " species " 

 in such a sentence as : " England possesses one dor- 

 mouse and one squirrel" is rather apt to make one 

 inquire as to the location of those favoured animals. 



There are eighteen excellent double-page maps, but 

 of course they are not so full of detail as is necessary for 

 a complete study of the subject. This, however, is no 

 great drawback in these days of cheap atlases. 



Travel-Tide. By W. St. Clair Baddeley. (London: 

 Sampson Low, 1889.) 



The writer of this volume has visited many different 

 parts of the world, and here he sums up the impressions 

 produced upon him by the most remarkable of the scenes 

 with which he has made himself familiar. There is 



