58 



The paraffin oil was boiled on this piiin[) witli finely divided cad- 

 rniinn. If there had been formed during the electrolysis only one 

 moditication of cadmium, we might expect that no transformation 

 would occur in the dilatometer, in consequence of the absence of 

 germs of a second form. From our earlier experiments (first paper 

 § 4j we know that even if a second modification were present the 

 retardation may be very strongly marked. 



We found in our first experiment that neither at 50°, nor at 

 80°, nor at iOO"^ did any change occur. 



After having removed the paraffin oil we washed the metal with 

 ether and brought it into contact with a solution of cadmium sul- 

 phate (12 hours at 100^ ; 48 hours at 50°). After this the dilato- 

 meter gave the following results (Table III). 



TABLE III. 



Temperature 



Duration of obser- 

 vations in hours 



Increase of level 

 in mm. 



Increase of level in 

 mm. per hours 



71.0 

 94.8 

 70.5 

 70.5 

 60.0 

 70.0 

 65.0 



'/4 

 53/4 



11 



24 

 1^/2 

 IV2 



— 351 

 + 132 



— 267 

 + 47 



— 138 

 + 70 



— 53 



— 468 

 + 528 



— 46 

 + 4 



— 6 

 + 46 



— 38 



There is a change in the direction of motion of the meniscus at a 

 constant temperature (70\5). The transition point is now between 

 65 and 70°. 



This change proves therefore that now (viz. after the treatment 

 at 100° and 50° with a solution of cadmium sulphate) there are 

 simultaneously present more than two modifications. 



9. Finally it may be pointed out here that the pyknometer cannot 

 be used to determine with exactness the density of the modifications 

 of cadmium formed by electrolysis, as this material always includes 

 constituents of the solution which has been electrolyzed. The water 

 may be driven out by melting the metal ; the salt will then flow 

 on to the surface of the metal and may be washed away, but for 

 exact determinations this material cannot be used. 



Utrecht, April 1914. 



VAN 't B.OYY- Laboratory. 



