r^6 



11. In order to melt the metal entirely, the dilatometer was 

 heated to 100° C. ; the change of volume having ceased, the metal 

 was chilled at 0° C. 



The observations carried out with the chilled metal are given in 

 Table II. 



TABLE II. 



At 97°. 22 C. fusion had already begun to take place. 



12. The measurements given in the tables I and 11 in conjunction 

 with those of Griffiths which show that the /i-modiftcation has cat. 

 par. a greater specific volume than the «-modification, indicate that 

 we have to deal with a case of monotropy. 



13. That at 94° we have not passed beyond a transition point 

 may be proved by showing that the transformation velocity does 

 not increase at higher temperatures (which would be the case above 

 a transition point) but that there exists a maximum of velocity. This 

 may also occur with monotropic transformations (for instance in the 

 case of /J-dibroinproprionic acid ^) and if this is really the case, it 

 indicates that the transition point which cannot be reached lies in 

 the neighbourhood of the melting point. 



14. The following experiments show that we really have to deal 

 with such a case with .sodium : the metal was melted in the dilato- 

 meter and chilled. 



After this the tran.sformation velocity (i^-sodium -*• «-sodium) was 

 determined at different temperatures. (Duration of observations 48 

 hours). The velocity was found to be : 



') 0. Lehmann, Molekularphysik 1, 197. Leipzig 188S. 



