17'J 



DR. K. H. GRIFFITHS AND MR. EZKR GRIFFITHS ON TIN-: 



IM-..MI tlie brief description of the method published* by NKRNST, it is impossible to 

 estimate the magnitude of any errors arising from the neglect of the loss or gain by 

 iM.liatiun, &c. It must be remembered that boiling liquid air is not at a steady 

 temperature and therefore the metal block suspended within the envelope could not 

 settle to the temperature of the surroundings ; hence, observations of the temperature 

 after switching off" the heating current, afford little information concerning losses or 

 gain by radiation. 



NERNST'S experiments, however, had one great advantage over those of other 

 observers at lower temperatures, inasmuch as the ranges of temperature employed 

 were small, e.g., 27 C. When we consider the curvature of the specific heat curve, 

 it is evident that changes of temperature of the order of 100 C. and upwards can 

 give little accurate information as to the value at the centre of such ranges. Two 

 metals, only, appear to have been examined by N ERNST, namely, lead and silver. For 

 lead he obtained the values of the atomic heat given in column II. below ; column III. 

 gives the values calculated from the modified EINSTEIN'S formula 



(A) 



= 3K 



where 11 is the gas constant, equal to 1'985 gr.-calories. 



For lead 



a = 58, & = 7'8xlO- 5 . 



In column IV. we give values obtained by extrapolation of the parabolic formula 

 representing the locus of our specific heat curve C. to 100 C., (see p. 174 supra). 



ATOMIC HEAT. Lead. 



* 'Journal de Physique,' tome he., 1910, p. 721. 



