Carhon at High Temperatures. 465 



Table I. 



Mean Specific Heat of Carbon to Boiling-point of Zinc (1040° C). 



Calorimeter and water equivalent to 514'5 grm. units. 





Weight of 

 carbon. 



Initial 



Final 



Increase 







tempera- 



tempera- 



of tempe- 



Specific heat. 







ture. 



ture. 



rature. 





I. 



4-21 



17-88 



20-50 



2-62 



0-314 



II. 



404 



161(3 



18 67 



2 51 



0-312 



III. 



4-20 



13-62 



16-L'5 



2-63 



0-314 



IV. 



5292 



13-92 



17-20 



3-28 



311 



V. 



5 -3.32 



14-22 



17-56 



3-34 



0-315 



VI. 



4-890 



13-40 



16-46 



3-06 



0-314 



VII. 



2-0^1 



17-08 



18-37 



1-29 



0-318 



VIII. 



4-190 



l.rSO 



18-45 



2-65 



0-318 



IX. 



5-7()0 



15-75 



19-30 



3-55 



0-310— Graphite. 



X. 



2-940 



16-34 



18-42 



208 



0-356— Cocoa-nut charcoal. 



XI. 



0-8:^64 



14-22 



14-83 



0-61 



0-366— Diamonds (black). 



The mean specific heat of gas-carbon between 1040° C. and 

 20° C. may be taken as 0-32. 



In order to try and find the specific heat of carbon at the highest 

 temperature we can in any way define with accuracy, a series of 

 tentative experiments were made with different forms of crucible 

 to ascertain the shape best adapted for observation with the oxy- 

 bydrogen blowpipe. After a number of trials, a cubical block of 

 lime, 2 inches in the side, pierced with two channels one fourth 

 of an inch wide at right angles to each other through the middle 

 of the mass, was found the most convenient form of apparatus. 

 The directions of the channels were inclined so as to meet in the 

 centre of the cube ; and in general only one of them passed com- 

 pletely through the mass. The carbon was placed at the junc- 

 ture of the two channels; and two powerful oxyhydrogen blow- 

 pipes had the apices of their cones meeting at this point. After 

 the interior was at a white heat, the carbon was inserted and kept 

 as long as possible. The mass of lime was then lifted and the 

 piece of carbon dropped into the calorimeter. 



Bunsen^s elegant experiments on the temperature of combus- 

 tion of hydrogen and oxygen under a pressure often atmospheres 

 define the limit as 2800° C. ; but in the ordinary oxyhydrogen 

 flame the temperature does not reach 2500° C, according to the 

 observations of Deville and Debray. 



On several occasions platinum was fused in the lime cube and 

 thrown into the calorimeter. From several concordant observa- 

 tions the temperature in no case was found to exceed 2100° C* 



* By transferring fused platinum the following results were obtained : — 

 6"75 grms. gave in one experiment 697 grm. units, and 6'7 grms. of metal 

 gave in a second observation 672 grm. units. The latent heat of platinum 

 was taken as 12 grm. units, and the mean specific heat as 0"042. 



Phil. Mag. !S. 4. Vol. 44. No. 295. Dec. 1872. 2 H 



