488 



during 24 hours at 40°. We found: 



(^ ^8. 642 and 8.643. 

 4° 



Its density (taken at 25°. 0) showed an increase of 22 units in 



the third decimal phice. 



8. The experiment of § 6 was repeated again Avith the metal 



25° 

 that had now a density of d —^ 8.642 (8.643) (Vide § 7). After 



having kept it during 24 liours at 60 — 70° in a solution of cadmium- 

 sulphate, we found (after chilling, washing etc.): 



25° 

 d — 8.631 and 8.633. 



4" 



At 60 — 70° there has been again a decrea.^-e of 10 units in the 

 third decimal place. 



9. The experiments of § 5 — 8 prove that there is a transitiontem- 

 perature between 40° and 70°. 



10. In order to fix this temperature more closely, we carried 

 out the following 



b. Experiments with the Dilatometer. 



In order to measure as accurately as possible the changes of 

 volume which the metal undergoes within short times, we used 360 

 grams of our metal K^. 



After having reduced the metal to turnings, we heated it during 

 24 hours in contact with a solution of cadmimnsulphate. The metal 

 was then chilled and washed and transferred into a dilatometer 

 which was then filled with paraffmeoil. This had been heated for 

 some hours at 200° (under reduced pressure) in contact with finely 

 divided cadmium, until there was no more evolution of gasbubbles. 



In order to reduce as far as possible the quantitj' of this oil the 

 expansion of which would have made the measurements more 

 troublesome, a quantity of small glass-beads was put into the bulb. 



11. The dilatometer was now kept at different but constant tem- 

 peratures by means of an electrically heated thermostat which we 

 shall describe in full later. The temperatures at which the readings 

 of the meniscus were made, remained constant within 0.002 degrees. 

 (A BECKMANN-thermometer was used in the thermostat). By this 

 device the dilatometer becomes an instrument of precision. 



The results are given in the following tables ^). 



^) The capillary tube (diameter of bore 1 mm.) was bent into a horizontal position. 



