the Elements Carbon, Boron, and Silicon* 



287 



First Series. 

 N =9-881. 



G. 



T. 



N. 



W. 



Co-T. 



0677 

 0-677 



98-9 

 99-0 



123-9 

 126-4 



1254 

 12-79 



01903 

 01909 



Mean specific heat between 0° and 99° =0-1906. 



Second Series. 

 N = 9-881. 



0-677 1 2271 

 0-671 2240 



356-2 

 347-7 



3605 

 3519 



02345 

 0-2341 



Mean specific heat between 0° and 225 °-6 = 



0-2348. 



For graphite the numbers were 



CV^o = 0*1904,1 



C -225-3 = 0-2350.J 



This specimen of amorphous carbon has therefore the same 

 specific heat as graphite for the temperature-interval 0° to 225°. 



D. The Specific Heat of porous Wood Charcoal. 



The numbers hitherto obtained for the specific heat of porous 

 carbon, viz. 



C °-i5° .= 0*165 (De la Rive and Marcet — method of cooling), 

 Ci 8 o-gs° =0*241 (Regnault — method of mixtures), 



lead to the probable conclusion that the specific heat of this 

 variety of carbon is identical with that of graphite, and that the 

 contradictory result of Regnault was due to the evolution of 

 heat by the contact of the porous substance with water. In order 

 to determine the specific heat of porous carbon with the greatest 

 possible accuracy the following experiments were carried out. 

 The middle part (about 2 centims. long) of a thin glass tube of 

 known weight was filled with porous carbon which had been 

 washed in acid, and at the ends of the carbon cylinder the tube 

 was narrowed so as to be only about 2 millims. in diameter. 

 The tube was now heated to slight redness for fifteen minutes, a 

 stream of chlorine being passed through it to remove the hy- 

 drogen contained in the carbon. Both ends of the tube were 



