﻿656 Mr. H. Davies on a Relation between Coefficient* of 



The right hand side of (4) can be expanded in a series 

 with ascending powers of T giving the tempeiature variation 

 of a. Thus 



a = ^m + 





2T C ' QlT e y ' (2T e ) 



• (5) 



The experimental values of coefficients of expansion and of 

 critical temperatures are commonly given with reference to 

 the centigrade scale. To transform from absolute to centi- 

 grade scales it is better to start with equation (4). Thus 



2(0 c +273) -(0 + 273) (20 e + 273)-0 



_i e 



20 c + 273 + (20 s + 273) 2 + * .... 



(SO 



The values of the constant term are tabulated for some 

 liquids below with the experimental values for comparison. 

 They were selected quite at random from Landolt and 

 Bornstein's tables. 



Table I. 



Liquid. 



Acetone 



Aniline 



Bromine 



Benzene 



Pentane 



Phenol 



Toluol 



Naphthalene 



Thymol 



Xyiol-o 



j Xylol-m 



0° C. 



a (Calc). j a (Exp.). 



237 

 426 

 302 

 290 

 197 

 419 

 321 

 468 

 425 

 358 

 346 



■001339 



•0008H9 



•001167 



•001172 



•001499 



•00088 



•001062 



•00082 



•000889 



■00101 



•00103 



•001324 



•O0082 



•00104 



•001176 



•001464 



•000834 



•001028 



•00075 



•000843 



•00092 



•00096 



The greatest difference between the experimental and 

 calculated values occurs in the case of bromine, where it is 

 nearly 12 per cent. The agreement in the other cases is very 

 satisfactory. 



The temperature variation of a can be calculated from the 

 second and succeeding terms. The values of the coefficient 

 of 6 are given in Table II. with the corresponding values 

 deduced from experimental data. 



