the Elements Carbon, Boron, and Silicon. 



289 



Table (continued), 



Third Series. 



N =6030. 





G. 



T. 



N. 



W. | Co_ 223 . 



Carbon 



1-410 

 1105 

 0-655 



1-410 

 1105 

 0-655 



1-410 

 1105 

 0-655 



1 2240 

 1221-6 

 1225-3 



8002 

 790-4 

 802-3 



132-7 \ 

 1311 J 

 1331 J 



0-2391 



0-2116 



0-0328 



02386 

 0-2114 

 00328 



0-2377 



0-2117 



00328 



Glass 



Platinum 



Carbon 1 



Glass 



Platinum 



Carbon 



Glass 



Platinum 



Mean specific he 



at of poro 



us carbon 



between 



and 223 



°-6= 0-2385. 



By comparing these numbers with those expressing the spe- 

 cific heats of lamellar graphite and of dense carbon we have : — 



Lamellar graphite. 



Dense amorphous 

 carbon. 



Porous carbon. 



C - 21 . 6 =0-1605 

 C«- 9 90= (H904 



C -225-3 = 2350 



C - 990 = 01906 

 C -225- 8 = 0-2340 



C - 23-5 = 01653 

 Co- 99«2 !SB 0'1935 

 Co-233-6= 0-2385 



From these it may be concluded that the specific heats of gra- 

 phite, of dense amorphous carbon, and of porous carbon are iden- 

 tical within the temperature-interval 0° to 225°. Although the 

 numbers obtained for graphite and for porous carbon differ so 

 much as 2 to 3 per cent, of their value, yet these discrepancies 

 may be accounted for by the difference in the conditions of the 

 two substances. To determine, however, to what cause these 

 differences are really due requires more delicate experiments 

 with absolutely pure substance. 



From Regnault's experiments it appeared that as many ther- 

 mally different modifications of carbon exist as there are physi- 

 cally different modifications. The above results, however, show 

 that this is not the case, and that, from a thermal point of view, 

 there are but two really different modifications of carbon, the 

 transparent (diamond) and the opaque (graphite, dense and po- 

 rous carbon). The high numbers obtained by Regnault, 



