July 8, 1909 J 



NATURE 



M 



hypothetical planet outside Neptune does not attract 

 comment. Since the satellites of Jupiter and Saturn 

 come under notice, more attention might have been 

 given to the moon and to the phenomena of eclipses. 

 The plan of the book, however, aims rather at the 

 description of the surface than of the motion of the 

 planets, though naturally the tale of the discovery of 

 Neptune is told once again. It might seem that there 

 is scarcely room for such a book, considering the 

 number of popular works that are extant, but there 

 is some difficulty in keeping even these works abreast 

 of the time. As an example we mav quote the sen- 

 tence, " Bestimmt sieben, wahrscheinlich sogar acht 

 Monde umkreisen Jupiter." Notwithstanding the 

 recent issue, there is here opportunity for correction 

 in the next edition. 



Untersuchung und Nachweis organischer Farbstoffc 

 aiif spcktroskopischem Wcge. By J. Formdnek, 

 with the collaboration of E. Grandmougin. Pp. 252. 

 Second edition. Part i. (Berlin : Julius Springer, 

 1908.) Price 12 marks. 

 The first edition of this work appeared in 190 1 in a 

 single volume. In part i. of the new edition which is 

 now before us, subject-matter to which only forty-twu 

 pages were devoted in the first edition has been 

 elaborated and added to so largely that it occupies the 

 whole of part i. The introduction deals with spectro- 

 scopic methods in general, but more particularly with 

 absorption spectra of coloured solutions and the influ- 

 ence of solvents, concentration, reagents, temperature, 

 &c., on the latter. Then follow chapters on the spec- 

 troscope, general observations on the relationship 

 between colour, absorption, fluorescence, and constitu- 

 tion of coloured compounds and dyestuffs, and on the 

 relationship between chemical constitution and absorp- 

 tion spectra of dyestuffs belonging to individual classes. 

 The latter include di- and tri-phenylmethane dye- 

 stuffs, quinoniinide dyestuffs, f^uorindene and tri- 

 phendioxazine, acridine dyestuffs, and anthraquinone 

 dyestuffs. No mention is made in this part of the azo- 

 dyes, or the dyes of the indigo group, while of natural 

 dyestuffs only alizarin is mentioned. It is to be pre- 

 sumed, however, that these important classes will 

 receive due consideration in part ii., which represents 

 the practical part of the work. 



Although a vast amount of work has been done 

 by different observers on the absorption spectra of the 

 organic dyestuffs, the information is so scattered as to 

 be difficult of access to the ordinary individual, and 

 this is probably the main reason why this important 

 subject has hitherto not received the attention which 

 it merits. There is, however, ample testimony that this 

 particular application of the spectroscope is being more 

 and more appreciated by the manufacturers of dyestuffs 

 on the one hand, and the users on the other. This 

 is borne out by the fact that such an eminently prac- 

 tical body as the Soci^t^ industrielle de Mulhouse has 

 made a pecuniary grant to the author to enable him 

 to publish the new edition. Prof. FormAnek has 

 made a life-long study of his subject, and a compre- 

 hensive and up-to-date book on this particular applica- 

 tion of spectrum analysis, such as the present edition 

 promises to be, would be much appreciated. It is to 

 be hoped that the completion of the work will not be 

 long delayed. 



On the Calculation of Thermochemical Constants. 

 By H. Stanley Redgrove. Pp. viii-l-102. (London : 

 Edward Arnold, 1909.) Price 6s. net. 

 There are a number of physical properties of sub- 

 stances, e.g. molecular heat of combustion, re- 

 fractivity, &c., which are chiefly additive in character, 

 so that their values can be calculated if we know the 

 necessary fundamental constants. It is, however, also 

 NO. 2071, VOL. 81] 



well known that these properties, while still remain- 

 ing additive, involve factors depending on the consti- 

 tution of the molecule, e.g. method of linking, ring- 

 formation, &c., all of which should be taken into 

 account in the calcukition of the value of the particular 

 property in the case of any given substance. It is the 

 thorough-going application of this principle in the 

 calculation of thermochemical constants, extended so as 

 to include, not only the specific thermochemical values 

 of double and triple bonds, but also the thermal value 

 of the " strain " in ring-compounds and of the single 

 bond in chain-compounds, that the book under review 

 expounds. The author's method of calculation has 

 already appeared in several articles published in the 

 Chemical Ncivs, on which the present monograph is 

 based. 



The author's method will best be understood from 

 the following : — Let H be the value of a hydrogen 

 atom plus the link joining it to a carbon atom. Let 

 C be the value of a carbon atom, not including the 

 value of its valencies; let L^, L,, L3, be the values 

 of the single, double, and triple bonds respectively. 

 Knowing the constants for four hydrocarbons, it is 

 possible to calculate the value of the following : — 

 C + 4H = c«, 2H-L,=;8, 4H-L, = 7, 6H-L^ = 5. These 

 are the " fundamental constants " for carbon and 

 hydrogen. Moreover, the formula of any compound 

 can be written in terms of these fundamental con- 

 stants, and the theoretical value so obtained can then 

 be compared with the experimental number. 



This method the author has illustrated by the cal- 

 culation of a large number of heats of combustion of 

 substances belonging to different groups of compounds, 

 and, with comparatively few exceptions, excellent con- 

 cordance with the experimental numbers has been 

 obtained. In this fact the method has its justification. 



In an interesting section the author discusses also 

 the relation between heats of combustion of ring-com- 

 pounds and von Baeyer's strain theory, and he shows 

 that in general there is perfect agreement. No simple 

 relationship, however, has been obtained between the 

 angle of deviation and the thermal equivalent. 



The book is one which deserves and will no doubt 

 obtain the attention of all who are interested in the 

 relations between the thermochemistry of compounds 

 and their chemical constitution ; and the method of 

 calculation is, moreover, one which will not improbably 

 find application in the case of other physical properties 

 of an additive character. It is an important addition 

 to the literature of thermochemistry. A. F. 



An Angler's Season. By W. Earl Hodgson. Pp. 

 xii + 299. (London: A. and C. Black, 1909.) Price 

 3s. 6d. net. 



-A BOOK from Mr. Hodgson is always worthy of the 

 angler's attention, and " An Angler's Season " is no 

 exception to the rule. Dealing as he does solely 

 with salmon and trout, and almost entirely with 

 Scotch waters, the author's season begins in January 

 and ends in October, and to each month a chapter is 

 allotted; throughout there is much good reading, a 

 deal of sage advice, and some controversy. Early in 

 February Mr. Hodgson is already at issue with the 

 dry-fly fisherman, and his attack on the " Hampshire 

 method " waxes furious, but he says nothing of those 

 who fish with the dry fly in Aberdeenshire waters and 

 find the method successful. Fault is also found with 

 some anglers for their " habitual indifference to the 

 weight of a basket " and their love of nature; surely 

 an angler is no worse for also being a naturalist, or 

 at least taking an interest in the natural history of 

 fishes. A study of what naturalists have written 

 would have shown the danger of Mr. Hodgson's 

 theory that taking- large fish only, and restoring all of 



