042 



(who foiiiid 300^), published some weeks ago. agree sufficiently .with 

 those of Le Chateliek. We shall discuss in a subsequent paper the 

 differences which exist amongst the results of the investigators mentioned 

 above. Whilst Benedicks mentions a second transition point (at 170°), 

 Max Werner was unable to find this point. The question as to 

 whether it really exists or not, may be left open for the moment. 



2. Since writing the above we became acquainted with the paper 

 of Le Verrier ^), which has been summarized by one of us^). 

 Le Verrier found that the specific heat of zinc varies greatly between 

 100 and 140° and that there occurs an absorption of heat within 

 this interval of temperature of — 8 calories. Tliis result indicates 

 that there exists here a transition point. Mr. G. de Bruin is carrying 

 out a systematic investigation in this direction. 



3. Benedicks and Ragnar Arpi have recently published ^) a new 

 investigation of this subject. In his first paper Benedicks pointed out 

 that "beziiglich der Frage, ob die fur das Zinc, puriss. Merck 

 (garantiert f rei von Eisen und Arsen in Staben) gefundenen Angaben 

 auch fur das absolut reine Metall geiten, bedarf es ebenfalls weiterer 

 Versuche". 



That there was no reason to suppose that this sample contained 

 impurities may be concluded from the authors' words: "Jedoch ist 

 es im Hinblick auf die Wichtigkeit der Reinheit dieses Produktes 

 fur seine Verwendung fur analytische Zwecke sehr wahrscheinlich, 

 dass die Menge von Fremdkörpern zu vernachlassigen ist". 



4. However Benedicks writes in his most recent paper: "Es ist 

 deshalb hier eine Revision der einschlagigen Verhaltnisse vorgenomen 

 worden, die zu ziemlich unerwarteten Ergebnissen gefiihrt hat. Xiimlich, 

 dass überhaupt keine AUotropiebeweise fur Zink z. Z. vorliegen". 

 He adds: " Abgesehen wird dabei zunachst von derjenigen Andeutung 

 von AUotropie, die neuerdings von E. Cohen und W. D. Helderman 

 durch spez. Gewichtsbestimmiuigen gefunden wurde". We shall 

 revert to this point later. 



5. The method followed by Benedicks and Arpi to discover 

 possible transition points was the same as used formerly by Benedicks, 

 viz. the determination of the electrical conductivity of the metal at 

 different temperatures. 



Whilst he found in his first determinations (working with zinc, 

 puriss. Merck) transition points at J 70° and 330° respectively, he 

 was not able to find them when he used "Zinc Kahlbaum" which 



i) G. R. 114, 907 (1892). 



'^) Ernst Cohen, Proceedings 17, 200 (1914). 



-) Zeitschr. f. anorg. Chemie 88, 237 (1914). 



