676 Dr. R. D. Kleeman on the Equation of Continuity 



also M 2 = 3'7. These two equations, substituting for K2 its 

 numerical value, give % = "734 and w 2 = -176. 



It is necessary next to discover a function which will 

 express the variation of K 2 with temperature. This variation 

 is small : thus in the case of methyl formate the value of K 2 

 or A decreases from 4400 to 2865 when the temperature 

 increases from 273 to 486. If the values of A given in 

 Table V. quoted above are plotted against the temperature, 

 it is at once apparent that they suffer from an accumulation 

 of errors of data which affects them irregularly, but on the 

 whole the values may be said to vary approximately linearly 

 with the temperature. Bearing in mind that K 2 must be 

 the same for all liquids at corresponding states, we may 

 therefore write 



K 2 = A- - -. 



c 



It was found that we may put A = 7222 and B — 4422 ; at 

 the critical state we have then Kg = 2800. The general 

 equation of state is then 



^ + 42(7222-4422|)(|J 3 ( S V^) 2 





,-(■734-176;-)} 



(8) 



But this equation, on account of its generality, cannot 

 be expected to agree very well with the facts in all cases. 

 A better agreement would be obtained by determining the 

 numerical quantities separately for each liquid under con- 

 sideration. These quantities would obviously, however, vary 

 only slightly from one substance to another. 



It will be of interest now to compare the above equation 

 of state with that given by van der Waals. Van der Waals' 

 equation is 



( a \- BT 



\ P+ v 2 )~m(v-by 



where a and b are constants which are supposed to be inde- 

 pendent of temperature, &c, but which vary with the nature 



of the liquid. The term -^ or ap'f corresponds to the intrinsic 



pressure of the liquid. Now we have seen that this term 



