8 



Prof. T. S. Humpidge. 



The quantity of heat (Q^) required to raise 1 gram of a substance 

 from 0° to t° can be expressed by the equation — 



Q, = U + + (lt\ 



where h is the true specific heat at 0°, and a. and (3 are constants. 

 From this equation the mean specific heat between any two tempera- 

 tures (£' and t) is 



c *, = h + a(t + o + ,8(*2 + tt r + t'*y. 



The numerical values obtained for the three unknowns from the 

 experimental values of c\< are 



h = 0-3756 ; a = 0-00053 ; p = - 0-00000038. 



A comparison of the value for the mean specific heats calculated from 

 the above expression with those obtained by direct experiment shows 

 that the two agree within the experimental errors, and that this 

 expression correctly represents the change in the specific heat of 

 gluointrm. 



f 



: t. 



c^, found. 



cy calculated. 



11° : 



100° 



0-4286 



0-4302 



13 : 



145 



0-4515 



0-4505 



11 : 



193 



0-4696 



0-4687 



15 : 



240 



0-4885 



0-4875 



14 : 



312 



0-5105 



0-5097 



11 : 



360 



0-5199 



0-5215 



17 : 



447 



0-5403 



0-5425 



The three constants being known, the true specific heat at any 

 temperature (ht) is found by making f=t, and the above equation 

 becomes 



Tc t = h + 2«* + 3/3*2, 

 or with numerical values, 



ht = 0-3756 + 0-00106* - 0-00000114*2, 



ht may be calculated — 



= 0-3756 

 = 0-4702 

 = 0-5420 

 = 0-5910 

 = 0-6172 

 = 0-6206 



whence the following values for 



: 



^100 " 

 ^200 : 

 &300 : 

 ^400 = 

 ^500 = 



