610 M. Regnault on the Specific Heat of Simple Bodies, 



Means . . 007468. 



007446. 



Hence at low temperatures the two isomeric modifications of 

 selenium have exactly the same calorific capacity. This result 

 is similar to that which I obtained with the two isomeric modi- 

 fications of phosphorus, ordinary phosphorus, and red phos- 

 phorus. In two such different conditions, phosphorus showed 

 calorific capacities which were evidently equal (Ann. de Chim. et 

 de Phys. 3rd series, vol. xxxviii. p. 129). 



Vitreous arsenious acid and opake arsenious acid also exhibit 

 no difference in their specific heats. It is nevertheless remark- 

 able that the enormous disengagement of heat which is mani- 

 fested at the moment at which vitreous selenium is transformed 

 into metallic selenium, should not produce any change in the 

 calorific capacity of this body. 



Selenium presents no fixed point of fusion or of solidification ; 

 when heated, it softens gradually, and only becomes completely 

 liquid at a temperature above 250 degrees. Every one knows 

 that in its viscous state it may be drawn out in very fine threads. 

 I melted a great mass of selenium in a large glass tube, and kept 

 in the middle of the liquid a mercurial thermometer, and followed 

 from minute to minute the cooling of the thermometer. From 

 260 to 40 degrees the decrease of the thermometer was perfectly 

 regular; at no point was there remarked one of those intervals 

 of delay, more or less prolonged, which are always observed at 

 the moment of a change of condition in bodies which pass from 

 the liquid to the solid state. 



I give here the series of temperatures observed from minute 

 to minute : — 



o 



5-8 



5-4 



5-3 



4-6 



4-9 



4-25 



4-0 



3-85 



3-4 



