586 



NATURE 



{Oct 3, 1878 



graphic plates drawn under his superintendence by R. 

 Mintern. Although not so finished in execution as those 

 of the late Mr. Ford, or quite so clear in detail as what 

 Franz Wagner has done for Dr. Peters in the same style, 

 these plates form a great addition to the volume, and 

 exhibit some of the special structures of the group in a 

 very efficient way. 



Of the general merits of the Zoological Catalogues 

 of the British Museum, and of the credit due to 

 the staff of the Zoological Department for their pre- 

 paration in the face of many difficulties, we have spoken 

 in a previous notice of one of this same series. ^ It is 

 much to be regretted, however, that more pains are not 

 taken to make the existence of these most valuable pub- 

 lications known to the world. No publisher's name being 

 on the title-page, it is difficult for the general public to 

 know how to procure them, and no information on the 

 subject is given in the volumes themselves. So far as 

 we know, they are not advertised in any way, and no 

 copies are sent out for review — certainly not to the office 

 of Nature; 2 so that it is only by chance that one be- 

 comes aware of their issue. On the Continent there are 

 many complaints about the difficulty of procuring copies, 

 and naturalists in London receive frequent applications 

 from their brethren abroad on this subject. This might 

 be all remedied by putting a publisher's name on the 

 title-page — a course adopted by all our principal scien- 

 tific societies for their publications — or even by adding to 

 each volume a list of the series, with some directions as 

 to how and where they are to be obtained. Another 

 mystery connected with these catalogues which we have 

 never been able to understand is why the authors of 

 them should not be allowed to write their own prefaces. 

 In some of the older volumes even the author's name is 

 ,not given on the title-page. This privilege has been con- 

 ceded of late years, but the prefaces continue to be written 

 by the "keeper of the department." We are told this is 

 a " regulation of the trustees " — an answer given, we may 

 observe, about many other rules and regulations at the 

 British Museum, of which no one can understand the utility. 



TIDY'S "HANDBOOK OF CHEMISTRY'' 



Handbook of Modern CJiemistry, Inofganic and Organic, 

 for the Use of Students. By Charles Meymott Tidy, 

 M.B., F.C.S. (London : J. and A. Churchill.) 



THIS work is divided, as is usually the case with 

 chemical text -books, into three large divisions ; the 

 first containing the chemistry of non-metallic bodies, the 

 second the chemistry of the metals, and the third the 

 chemistry of organic substances. 



In the first two chapters, preliminary to those discuss- 

 ing systematically the natural occurrence, preparation, 

 and properties of the non-metals, the author describes 

 the more general principles involved in the science, em- 

 bracing such topics as nomenclature, atomic and molecu- 

 lar combination, combination by volume, atomicity and 

 quantivalence, &c. The subjects here touched upon are 

 clearly dealt with, and Mr. Tidy' s style of writing cannot 

 fail to attract the attention of the reader. 



The subsequent portion of the book, consisting of 



See our review of Sharpe's " Catalogue of Birds," Nature, vol. xvi. 

 P- S41: 



'' Since the above was in tjrpe a copy of Dobson's " Catalogue " has been 

 sent us by the author.— Ed. 



Chapters III. to IX., embraces the consideration of the 

 individual properties of the different non-metallic ele- 

 ments ; and although this part of the work abounds in 

 valuable and, as far as we can see, accurate information, 

 there is an important point with regard to it upon which 

 we cannot thoroughly congratulate the author ; namely, 

 the order in which he has arranged the non-metallic 

 elements. He commences with oxygen and finishes with 

 hydrogen. We cannot at this moment see, nor can we 

 find any explanation in the preface or otherwise, stating 

 why this particular order should be adopted ; and we are 

 inclined to think that, for the sake of instruction in 

 chemical order and classification, it indicates a defective 

 appreciation of the wants of the student. It appears to 

 us that, keeping this point in view, the order of such a 

 text-book as Mr. Tidy's should be that in which the 

 elements forming the least complex compounds are first 

 taken, then those which possess a larger number of 

 compounds and of a more complicated nature. 



This becomes' evident if it be considered what the 

 student is met by in reading this portion of the book, 

 where, instead of first being made acquainted with the 

 properties of hydrogen, the body now almost universally 

 adopted as our standard of reference for the atomic 

 weights of the elements, for the densities of gases, &c., 

 he has to consider oxygen "a common and important 

 substance, certainly," but not one which is now taken as 

 our standard, or which forms the simplest combinations, 

 so far as its own relations are concerned, with other 

 bodies. The reader then passes, in the next chapter, to 

 the consideration of the group of elements, consisting of 

 fluorine, chlorine, bromine, and iodine ; bodies having a 

 simpler volume relation to hydrogen than oxygen has : 

 and he is then introduced to a long series of compounds, 

 the oxyacids of the halogen series, where three elements 

 take part in the combination before he has become 

 acquainted with compounds containing only two, such as 

 hydrochloric acid or water. Nay, more, he has to 

 consider acid bodies containing hydrogen — reads equa- 

 tion after equation in which the body water occurs as a 

 product of decompositions, without his previously having 

 learned anything either about the preparation and proper- 

 ties of hydrogen, or the composition of water. 



Again, in the arrangement of the subjects treated of in 

 the chapter [dealing with the special consideration of 

 hydrogen (Chap. IX.) we think there is room for improve- 

 ment ; and that it would be better to adopt an arrange- 

 ment depending on the simplest volume relations of the 

 substances, placing them in the series monatomic, diatomic, 

 triatomic, and so on, instead of first taking water where 

 the ratio of hydrogen to the other substance is 2 : i, then 

 the halogen compounds of hydrogen where the ratio is 

 more simple, viz., i : i, then its compounds with nitrogen, 

 phosphorus, and arsenic, where the ratio is 3 : i, then 

 back again to sulphuretted hydrogen, where the ratio is 

 2 : I, and finally, to the simple compound of carbon and 

 hydrogen with the ratio 4 to i. If the student is at all 

 thoughtful, and has paid any attention to the sections on 

 "combination by volume," &c., which we have already 

 stated to be clearly written, he will find himself at the 

 end of the consideration of the non-metals rather at a 

 loss to form any idea of order or classification as regards 

 chemical bodies. 



