The mean heat capacities of silver and nickel between 0 °C. and various temperatures from 100° to 500 °C. have been determined by the method of mixtures, an all-copper adiabatic calorimeter being used.A brief discussion deals with the difficulty of obtaining accurate values of the true heat capacity, Cp, from mean heat capacity, [Formula: see text], measurements.The following table gives a brief summary of the results:100° 150° 200° 250° 300° 350° 400° 450° 500°C.Silver[Formula: see text] 0.2364 0.2376 0.2389 0.2401 0.2415 0.2427 0.2440 0.2452 0.2465Cp 0.2389 0.2413 0.2439 0.2463 0.2490 0.2514 0.2540 0.256 0.259Nickel[Formula: see text] 0.4536 0.4636 0.4741 0.4856 0.4972 0.5117 0.5162 0.5177 0.5188Cp 0.474 0.495 0.517 0.543 0.575 0.627 0.531 0.529 0.527The uncertainty in [Formula: see text] of both silver and nickel is about 0.2%, in Cp of silver from about 0.2% at 100 °C. to nearly 1% at 500 °C., in Cp of nickel from about 0.5% at 100 °C. to 2% at 350 °C. and above.