633 



condition. H. F. Wkbku ^) tbniid the spccilic lical ofcarhon (at UrC.) 

 0.1128 ill tliü form of dicinioiul 

 0.1604 ,, , ,, ,, graphite 

 0.1653 ,, ,, ,, ,, charcoal 



Ernst Cohen and E. Goldschmidt ') found (hat the density oi' trhite 

 tin is 7.28, that of gray tin 5.8 (at (he same temperature) wiiile 

 KÓTARÓ Honda ^) has stated that (he specific magnetic susceptibility 

 (X X 10') of white tin is -f- 0.025, while that of (/raj/ tin is — O.'SÏ 

 at the same temperature. Here even the sign is changed. The existing 

 data on the physical constants of metals known until now are thus 

 to be considered as entirely fortuitous values which depend on the 

 previous thermal history of the material used. Those i)liysical constants, 

 which refer to a well defined condition of the metal are so far 

 unknown. In order to determine these, and only these have a definite 

 signification and are reproducible, we shall have to carry out in the 

 future all measurements for the pure ct,^,y.... modifications of the 

 metals. 



4. Considering for instance the important part which the specific 

 heats of the metals have played in chemistry and physics during 

 the last few years, it is evident that a revision of these constants is 

 wanted. 



5. What has been said abont the specific heat holds evidently for 

 every other physical constant. In our paper on the allotropy of 

 bismuth ^) we pointed out, that numerous phenomena which had been 

 observed in the study of density, electric conductivity (also under 

 pressure) conductivity for heat, melting point, thermoelectric foi'ce, 

 the HALL-effect etc. and which had not been explained, may find 

 their explanation if the facts recently found are taken into account. 



6. In this way a new field of research for chemists as well as 

 for physicists presents itself. Whilst it will be the task of the chemist 

 to prepare the pure modifications and study their physico-chemical 

 properties, the physicist will require to turn his attention to the 

 determination of their physical constants. 



7. From a physico-chemical standpoint it will be very important 

 to study the electromotive behaviour of the allotropic modifications 

 mentioned above. The (ransitioncell of the sixth kind which I 



1) Pogg. Ann. 154, 367, 553 (1875). 



2) Zeitschrift fur physik. Chemie. 50, 225 (1905) 



3) Ann. d. Physik 32, 1027 (1910) ; The Science Reports of tlie Tölioku Imp. Univ., 

 Sendai, Japan. 1, 1 (1912). 



■t) Zeit&chr. f. physik. Chemie 85, 419 (1913). 



