422 



NA TURE 



[February lo, 1910 



dependence of crops and of live stock and its fluctuat- 

 ing financial equilibrium. Nor have Ville's formute 

 for compound manures survived. The amount of food 

 a plant requires is known to be modified by the water 

 supply, the temperature, and the general soil con- 

 ditions. It is clear that no one formula could possibly 

 suit all cases; indeed, we might sum up the difference 

 between Ville's views and those current now by 

 saying that Ville regarded the supply of plant food 

 as the dominating factor in determining fertility, 

 whereas we now know it is only one of several 

 equally important factors. 



The lectures are interesting to read and must have 

 been delightful to hear; they will form valuable 

 material for the historian of agricultural science when 

 he arises, not only by reason of the views set forth, but 

 also because of the numerous balance-sheets and state- 

 ments of costs. For their historical interest also thev 

 will be read by the serious student of agricultural 

 chemistry, who indeed is already attracted to them by 

 the fact that they have interested Sir William Crookes. 



Certain alterations have been made in the text, so 

 that the lectures are not quite in their original form. 

 The editors have preferred to do this rather than to 

 make corrections in footnotes, a plan which, if more 

 cumbersome, would have had the advantage of pre- 

 serving the historical value of the book. \ chapter 

 has also been added on the fixation of atmospheric 

 nitrogen. All fixation methods attract much popular 

 attention, while the electrical method first indicated 

 by Sir William Crookes is already a rich and promis- 

 ing addition to our agricultural resources. 



E. J. RlSSELL. 



MODERN CHEMISTRY. 

 Handhuch tier anorganischen Chemie. Herausgegeben 



von Dr. R. Abegg und Dr. F. .\uerbach. Drifter 



Band, Zweite .^bteilung. Pp. xii + 921. (Leipzig : 



S. Hirzel, 1909.) 

 ■' I 'HIS stately volume of more than 900 pages treats 

 J- of the elements of the fourth group of the 

 periodic system, namely, C, Si, Ti, Ge, Zr, Sn, Pb, 

 and Th. It opens with an excellent comparative sum- 

 mary by .\begg and Brauner of the general chemical 

 and electrochemical relationships of the members of the 

 group. Then comes a truly magnificent monograph 

 on carbon by Weigert, covering 276 pages, with a 

 Titerature-index containing 1307 references. It would 

 be quite impossible in a short notice such as the pre- 

 sent to give any adequate idea of the masterly manner 

 itn which the author has dealt with his great subject, 

 so that a few references must suffice. In dealing with 

 •the allotropic forms of carbon, the usual purely de- 

 scriptive account is followed by an extraordinarily in- 

 teresting discussion of the energy- and stability- 

 relationships, in which the researches of Schenck and 

 Heller, and of Smits, are dealt with. The author also 

 applies Nernst's theorem to the problem of the 

 transition-point between diamond and graphite, but 

 an arithmetical error appears to have crept into his 

 calculation here. 



The highly important theoretical and experimental 

 researches on the formation, dissociation, and stability- 

 NO. 2102, VOL. 82] 



relationships of the hydrocarbons are treated very fully, 

 Nernst's thermodynamical theorem serving here (as 

 elsewhere) as a basis for calculation. A good account 

 is also given of Bone's work on the oxidation of 

 hydrocarbons. 



Under the heading of "Flame" the author does not 

 fail to give us a lucid account of the modern work of 

 Haber and his collaborators, whilst the subject of ex- 

 plosions introduces the reader to the work of Mallard 

 and Le Chatelier and Dixon. 



The chemistry of carbon has afforded the author a 

 splendid opportunity of familiarising the chemist with 

 the thermodynamics of high-temperature gas equili- 

 bria, and he has taken good advantage of it. The 

 treatment of such highly important subjects as the 

 dissociation of CO^, the C — CO^ — CO equilibrium, the 

 water-gas equilibrium, and various heterogeneous gas- 

 equilibria, such as C— N— C^iy,, C~S— CS,, C— NH, 

 — HCX — H, is excellent. The treatment of these 

 matters brings the author to the discussion of such 

 fundamental questions as the free energy of carbon 

 combustion and the quantitative measure of the re- 

 ducing power of carbon and its simpler gaseous com- 

 pounds. What a vista is opened here to those who 

 have the eyes to see and the minds to understand ! 

 It is a painful reflection to realise how soon all this 

 will be as familiar to the trained modern German 

 chemist as the laws of Dalton and .-Xvogadro, whilst 

 the progress of scientific chemistry in this country is 

 still retarded by the false prophets who are afl^righted 

 by the sight of an algebraical symbol, and grievously 

 lament the advance of physical chemistry. 



There is an excellent and suggestive account of 

 photochemical plant synthesis, and of the free-energy 

 changes involved in biological metabolisms. 



The heterogeneous equilibria presented by solid CO, 

 in its various forms, and the ionic dissociation of 

 aqueous solutions of carbonic acid, are well treated. 

 More technical questions, such as the manufacture of 

 coal gas, the calorific power of fuels, and the light 

 efficiency of burning oils, come in for their share 

 of discussion. 



Enough has been said to give some idea of the 

 scope and method of this splendid monograph. It is 

 to be sincerely hoped that English chemists will care- 

 fully study it. 



The next article (by Grossmann) deals with silicon 

 and its compounds, and is full of interesting things. 

 .\s befits the theme, a very full account is given of 

 .SiO,, the silicic acids, and the silicates. Here we find 

 an excellent resume of Tschermak's interesting re- 

 searches on the constitution of the silicates, together 

 with the criticisms of Jordis, van Bemmelen, and 

 Mii gge thereon. 



.Another very interesting section deals with the work 

 of Vogt, Doelter, and Allen and Day on the silicate 

 melts. 



Silicon is followed by a compact and up-to-date 

 article of twenty pages on glass, by Schaller. 



Titanium is dealt with by Jacoby. Here we find 

 a very full discussion of the important work of 

 Diethelm and Foerster on the electrochemical reduc- 

 tion of acid titanic sulphate solutions. 



Germanium and zirconium are well presented by 



