Jantjaet 27, 1911] 



SCIENCE 



147 



ethylene diamine, we can imagine two possible 

 arrangements with the cobaltammine molecule — 



/CI 

 Co^Cl 



\MHj— NHj— NH— NHj-Cl 



I I I I 



CHs— CHj CH^ — CH, 



CI 



Co— CI CHj CHj 



\ I I 



NHj— NH2 -NH — NHj— CI 



I I 



CII2 CHj 



so that we might attribute the isomerism in these 

 compounds to this difference. Now, in the am- 

 monia compounds such an isomerism could not 

 occur, owing to the similarity of all four am- 

 monia groups. We should therefore expect to 

 find no isomerism in the case of the ammonia- 

 compounds of the type [ (NHaJ^CoCls]; and, as a 

 matter of fact, no such isomers are known; the 

 compound ecdsts in one form only. 



And again on page 125, in summarizing the 

 whole controversy, the author states : 



The question at issue is quite clear. Jorgensen 

 points out that if we take the three cases of the 

 diehloro-diethylene-diammino salts, the dinitrito- 

 tetrammino salts and the dichloro-tetrammino 

 salts, two isomeric series are known in the case 

 of the first two sets, but the dichloro-tetram- 

 mino compounds occur in one form only — 



Occur in two forms 



X Occur in two forms- 



fco^-'^lx 

 L ens J 



Co .-3,. X Only one form known. 



So that in each case where isomerism is observed 

 there are either two nitro-groups or two ethylene 

 diamine molecules. Where these are both absent, 

 no isomerism occurs. Werner, on the other hand, 

 maintains that his theory accounts better for the 

 facts, though he has not teen able to produce the 

 two isomeric tetrammino salts which, according 

 to his views, ought to exist. The non-production 

 of these salts is specially significant when we 

 consider how easily we can transform one di- 

 ethylene-diamine isomer into the other; evapora- 

 tion with mineral acids produces one form, from 

 which the other can be regenerated by evaporating 

 with water after making the solution neutral. 



Briefly, Dr. Stewart contends that Werner's 

 views are untenable as he has not been able to 



prepare the isomeric modification of dichloro- 

 tetrammino cobaltic chloride. This is the 

 crowning argument with which the chapter is 

 closed. 



Unfortunately for the argument, Werner 

 published in 1907 in so accessible a journal as 

 the Berichie der Deutschen Chemischen 

 Oesellschaft, Vol. 40, p. 4817, a full account of 

 the discovery, the method of preparation, and 

 the properties of this second and isomeric 

 modification of dichloro-tetrammino-cobaltic 

 chloride. This was no accidental discovery, 

 nor the result of haphazard experiment, but a 

 logical consequence of the extension of 

 Werner's views to the complicated poly-nu- 

 cleal compounds, a field brilliantly developed 

 by Werner during the past twelve years, but 

 not mentioned in the chapter on Cobaltam- 

 mines. 



The critic can not ailord to be careless in 

 keeping up with the literature of a subject. 

 The plea of recent publication of Werner's 

 work on this compound can not be put 

 forward, as Dr. Stewart has included in this 

 chapter the still later (1908) published views 

 of Eamsay and of Friend; indeed, the date of 

 his preface, September, 1909, shows that the 

 manuscript was in hand two years after Wer- 

 ner's announcement in the Berichte of his suc- 

 cess in preparing the isomeric modification of 

 dichloro-tetrammino-cobaltic chloride. 



Chas. H. Heety 



Uhtvebsitt or North Cakouna, 

 Chapel Hill, N. C, 

 December 16, 1910 



/ 



SCIENTIFIC BOOKS 



The Differentiation and Specificity of Cor- 

 responding Proteins and Other Vital 

 Substances in Relation to Biological Classi- 

 fication and Organic Evolution. The Crys- 

 tallography of Hemoglobins. By E. T. 

 Eeichert and A. P. Brown. Washington, 

 D. C, published by the Carnegie Institution 

 of Washington. 1909. 



This is an important and very interesting 

 work, the combined production of a physiol- 

 ogist and a crystallographer. This review 

 will be restricted to a consideration of some 



