176 Dr. H. F. Weber on the Specific Heat of 



A. Clear . . . 48-sided, weighing 446 milligrms. 



B. „ ... 24-sided, „ 615 „ 



C. „ ... 24-sided, „ 357 „ 



D. Brownish . . 8-sided, „ 402 „ 



E. Greenish yellow 8-sided, „ 345 „ 



F. Transparent . spherical, „ 1397 „ 



The total weight was therefore 3*562 grms. 



The thermic relations of these six specimens were not altoge- 

 ther identical. From a number of determinations, the average 

 specific heats for the temperatures 0° to 100° were deduced as 

 follows : — 



A + B + C = 0-1438] 



D + E =01451 I 



F =0-1485 J 



The evidently not perfectly homogeneous masses D, E, and F 

 would therefore have been rejected had it not been for the con- 

 sideration that the determination of the specific heat for the 

 temperature-interval —30° to -f 30° could not be trusted beyond, 

 at the furthest, the third place of decimals when working with 

 the quantities of diamond A, B, and C only. 



This degree of certainty I did not, however, deem sufficient 

 for determining the existence of an inflection-point in the curve 

 of the specific heat indicated by preliminary experiments. As the 

 determination of this point appeared to me of the utmost impor- 

 tance, I sacrificed the advantage of working with absolutely pure 

 material for the gain of being able to determine with the greatest 

 possible accuracy the specific heat of the diamond at and near to 

 the temperature 0°. In all the series of experiments the total 

 quantity of diamond mentioned above was used. 



The following Tables give the data and results of 27 experi- 

 ments, having for their object the determination of the specific 

 heat of diamond for nine different temperatures between —80° 

 and +280°. 



G = the weight of diamond used. 



T =the temperature, measured by the air- thermometer, of 

 the diamond at the moment when it touched the 

 water in the calorimeter. 



N = the number of divisions on the scale-tube through 

 which the mercury thread was displaced after bring- 

 ing the substance heated to T into the instrument. 

 (The direct readings were reduced to the average 

 bore of the tube, and then corrected for the inde- 

 pendent oscillation of the mercury thread before the 

 introduction of the hot substance.) 



