486 



Leitungsfahigkeit stattfand", and "Wenn reines Kadmiiim über 80°C. 

 erhitzt wird, so wird es iiusserst spröde, ja, es kann sogar in einem 

 heissen Mörser mit der grössten Leichtigkeit gepulvert werden. Wir 

 würden die Bestiramiingen der Drahte nicht haben ansfüliren können, 

 wenn sie nicht überfirnisst gewesen waren, da sie sonst durch das 

 Bewegen des Oeles beim Umrühren in Stücke zerfallen waren. Es 

 ist bemerkenswert, dass diese Aenderimg in der molekularen Be- 

 schaffenheit der Drahte nicht irgend erheblich in der Leitungsfahig- 

 keit sichtbar wird." 



These remarks formed tlie starting point of the following research. 



2. The experiments on tin and bismuth had proved that metals 

 may show very great retardation in undergoing molecular changes, 

 at temperatures either above or below their transitionpoints. This 

 reluctance to undergo change is doubtless one of the reasons why 

 the allotropy of the metals mentioned above, which play an im- 

 portant role in industry, remained undiscovered until so late a period. 



Anticipating our results with cadmium, we state that the same 

 may be said about this metal. Cadmium gives at 65° C. an allotropic 

 (enantiotropic) modification; the very strongly marked retardations 

 have concealed the allotropic change from the numerous investigators 

 who studied this metal in different directions. 



3. Until the present we have used two methods of investigation. 



a. Experiments with the Pycnometer. 



The details of these determinations will be described in our paper 

 in the Zeitschrift fur physikalische Chemie. 



We used a form of pycnometer which has already been described 

 (volume about 25 cc). The thermometers which could be read with 

 an error not exceeding 0°.01 had been compared with a standard 

 of the Phys. Techn. Reichsanstalt at Charlottenburg— Berlin. Gener- 

 ally we used water as a liquid in the pycnometer, but as a control 

 we sometimes substituted paraffmeoil for it. 



All determinations we carried out in duplicate (using 16 — 30 grams 

 of the metal). The difference between two of these never exceeded 

 three units in the third decimal place. The metal (Cadmium-"Kahl- 

 baum") was purchased from Kahlbaüm — Berlin. We were not able 

 to detect any impurity in 100 grams of the material. We received 

 it in two consignments (flat rods) which we shall distinguish by the 

 letters A\ and K^ . 



The density of K^ we found to be: 



dt_ 8.635; 8.632; 8.633; 8.633 mean 8.633 

 4° 



