360 



Some of the curves, which relate to these organic liquids, are 

 reproduced here in the usual graphical way (fig. 9) ; the corresponding 

 critical temperatures of the liquids, so far as thej are known, are 

 mentioned and written between () behind the names of the 

 substances investigated. 



19. Salts of the Alkali-Metals. 



XVI. 



Molecular weight: 74.56. 



Radius of the Capillary tube: 0.04736 cm. 

 at 15° C. The expansion-coefficient is here 

 0.0000083. 

 Depth: 0.1 mm. 



The salt melts sharply at 771° C; after four hours heating between 

 900° and 1100°, it solidifies at 769° C. It evaporates rapidly at 980°, 

 at 1160° with great speed. Just as in the case of the other alkali- 

 salts, the vapours are doubtlessly acid, while the solidified mass gives 

 an alkaline reaction, if dissolved in water. The gradual dissociation 

 lowers the value of the maximum pressure more and more, as is 

 seen from repeated experiments after a longer heating 1100° C. 



As some illustrations of the changes caused by the commenced 

 dissociation of the salt, the following measurements are given, which 

 were made after a heating at 8,50° and 1150° C. during full four hours: 



At 848° C. the maxlmumpressure was found to be 2.821 mm. mercury 

 904 2 720 



» 941 „ „ „ „ r, n r, V 2.645 „ 



„ 956.5 „„ „ „ »»«» 2.615 „ „ 



„ 1037 „„ „ „ j>»»» 2,455 „ „ 



All values are evidently lower than the previously observed ones, 

 and at the lower temperatures, at which the observations were made 

 after the longest heating of the salt, the decrease is most appreciable. 



