60 



montlis. We used a special Üiermostat, which will be before long 

 described. The temperature was determined by means of a Beckmann 

 thermometer. It remained constant within some thousandths of a 

 degree. 



The results are shown in Table I. 



TABLE I. 

 Temperature 25°.00. 



Time in hours 







'Is 



22/3 



42/3 



112/3 



Level of the 

 meniscus (mm.) 



526 

 425 

 252 

 219 

 181 



A strongly marked contraction at constant temperature occurs. 



5. As the metal contains a certain amount of zinc oxide in 

 consequence of its fine state of division, rhe question might arise 

 whether the contraction observed may be attributed to some chemical 

 reaction between the oxide and the paraftin oil. 



In order to investigate this point more closely we tilled a dilato- 

 meter (100 cc.) with zinc oxide and the same paraffm oil we had 

 used in the experiment described above. After having evacuated it 

 at the Gaede pump we put it into a thermostat at 25°.00. The 

 meniscus did not show any change in 24 hours. The contraction 

 observed in our first experiment has consequently to be attributed 

 to a change in the metal. We intend continuing our investigations 

 on the different modifications of zinc present in. the "atomized" metal. 



Utrecht, April 1914. van 't ]^0¥v- Laboratory. 



Chemistry. — ''The al/otropi/ of Ct>/>/9dr". II. By Prof. Ernst Cohen 

 and W. D. Helderman. 



1. We have also continued our investigations on the allotropy 

 of copper in the direction indicated in our second paper on the 

 allotropy of cadmium. 



The dilatometer had shown (§ 4 of our first paper) that there is 

 a transition point at 71°.4. We used the same method described in 

 our second communication on cadmium in order to determine if 



