98 



17. From these tables it is evident that the velocity of melting 

 at tiie same temperature is oet. par. greater with /?-soditnn than 

 with «-sodium. Consequently the quantity of heat wanted to transform 

 1 gram of solid /^-sodium into the molten state is less than that 

 which must he added for that purpose to the same quantity of 

 «-sodium. From this we may conclude that the transformation 

 /J-sodium — ^ «-sodinm is accompanied by an evolution of heat. The 

 fact that this heat of transformation is positive, proves that ?ƒ there 

 exists a transition point it is to be looked for in the direction of 

 higher temperatures '). The facts described in ^ 14, prove that such a 

 transition point does not exist and consequently sodium is monotropic. 



18. Finally it may be pointed out that Hagen'), who determined 

 the coefficient of dilation of sodium (between 0° C. and its melting 

 point) by dilatometric measurements, was not able to observe these 

 phenomena as the quantity of metal used by him (40 grams) has 

 been too small. 



The value of this physical constant determined by this author is 

 consequently fortuitovx and must be redetermined with the pure 

 a- and /^-modifications. 



We express our best thanks to Dr. H. R. Kruyt to whom we 

 are indebted for many \akiable remarks. 



Utrecht, April 1915. van 't HoFF-Laboratory. 



Chemistry. — "Action of met/uj/et/n/Ikefone on 2. 3. 4. G. tetranitro- 

 /j/ieni/Imethi/Initirimine". By Prof. P. van Romburgh. 

 (Communicated in the meeting of April 23, 1915). 



As stated by me previously'), this nitramine reacts readily with 

 alcohols and amines. Water also acts on it with formation of nitrous 

 acid and of 2. 4. 6. trinitromethylnitraminophenol. Whereas at the 

 ordinary temperature this action proceeds very slowly it takes place 

 fairly rapidly at boiling temperature. 



In order to get to know more accurately the progressi\e change 

 of the reaction some previous investigations were made a few 

 years ago by me conjointly with Dr. Sinnige, which gave the result 



') Bakhuis Roozeboom, Die lieterogenen Gleichgewicljte vom Standpunkte der 

 Phasenlelire. 1, 178; Braunscliweig 1901. 

 2) Wied. Ann. 19, 43R (1883). 

 ■*j r.ec. 8, i2T5 (1889). 



