.')0 



eluinge of tliese allotropic niodificatious both below and above their 

 transition points. As we pointed out in our papers on the allotropy 

 of copper and zinc, the possibility that there might be present at 

 the same time more than two allotropic forms had to be taken 

 into account. 



If this were the case, a variation in the previous thermal history 

 might have an intluence on the transition temperature. 



The samples which had given 64°. 9 as their transition point 

 (Vide § 11 of our tirst paper) only differed by the fact, that the 

 second one had been in the dilatometer at 100° in contact with 

 paraffin oil for 36 hours after having given 64°. 9. At the end ot 

 this time the measurements were made, which are given in Table II. 

 On continuing our investigations we got the impression that this 

 difference in the thermal history of the samples might not have been 

 large enough to determine whether a third modification can be 

 formed. As a result of the following considerations we carried out 

 some new experiments. 



2. If in our sample K^ (first paper) there had been present 

 originally more than two modifications, it might be possible that 

 the greater part of the modification(s) which is (are) stable at higher 

 temperatures had been changed into the /"'-form, as the sample 

 had been heated at 101° 0. for 24 hours in contact with a solution 

 of cadmium sulphate. In this case the heating at 100°, which 

 followed the first experiment with the dilatometer. might have had 

 no perceptible influence on the transition point which is in accordance 

 with the results given in tables I and II. 



3. We now varied the pre\'ious thermal history of A', very 

 markedly. For this purpose the metal was taken out of the dilato- 

 meter and chilled by throwing it into water. After this it w^as put 

 into a new dilatometer without previousli/ treating it with a solution 

 of cadmium sulphate at 101°. The dilatometer was then kept at 

 70°.0; the temperature remained constant within 0.003 degrees. The 

 meniscus fell in 3^/4 hours 143 mm. while we observed formerly 

 (first paperj a strongly marked increase of volume at the same 

 temperature. 



4. In order to control this result, we carried out the following 

 experiment : 



A fresh quantity of the metal ("Kahlbaum" — Berlin) weighing 

 about 300 grams (A^,) was melted and chilled. We then turned it 

 into thin shavings on a lathe and put it into a dilatometer ; the bulb 



