of the Liquid and Gaseous States of Matter, G7f> 



Equation (7) may then bo written 



P 



13 3 



_& f> w» + I//s + 



P , r t+ -^ l , * . 



t~P~ — I — i IP + t £ — " =0. 



A 3 \ A 3 ?i 2 / r A 3 ^ 2 



Now, if we form the equations of condition for equal roots, 

 it will be found that if we put 



_ u \ 



U* 



where t^ and t* 2 are numerical constants, we obtain two 

 equations of the form 



RT Pc 





m Mo 



where Mj and M 2 are functions of u 1} u 2 , and K 2 . We have 

 seen that we must arrive at equations of this form, and the 

 numerical constants iii and u 2 must be so chosen that they 

 agree with the facts. It is necessary first to obtain the 

 value of K 2 . We have seen that 



p «= L >= A © 73( ^ mi): 



and K 2 is therefore the value of A at the critical point. 

 Without finding the exact nature of the variation of A with 

 temperature, it will be seen from an inspection of the values 

 of A of methyl formate in Table V.,| which have been calcu- 

 lated up to the critical point, that the value of K 2 is about 2800. 

 If the pressure in the equation of state is expressed in 

 atmospheres 



™ 2800 x 4-2 xlO 7 t1 - cnn 

 K 2 = ^ = 11/, 600. 



The mean value of Mj can be deduced from the fifth column 

 of Table IV. t, this giving Mj = (136-8) 2 . (Through an over- 

 sight it was not mentioned in the paper that the values in 

 this column are only relatively correct, the absolute values 

 being obtained by dividing each value by 4"54.) We have 



* (a) pp. 794-795. 

 t (a), p. 797. 

 X (a) p. 78S. 



2 Y2 



