Laws of Molecular Force. 229 



adding l/2v to Ramsay and Young's values of pv for volumes 

 of ethyl oxide below k, to determine the form of the function 

 yfr(v). This was found, after a rather tedious search, to come 

 out in the simple form 



VT(»-/3)/B ; 



so that finally we have the following as the equation for ethyl 

 oxide below the volume k : 



- ^"•f-3> 



l_ 



2v> 



JL5 V — ft, 



with the following values for the constants : 



R' = 25R/13, k'=7k/6, B = 63-l, 0=1-11, 

 R, k, and I as before. 



I propose to call this the infracritical equation. It is to be 

 noticed that we have introduced only two additional constants ; 

 so that, as regards number of constants, we could hardly 

 look for a simpler form. 



Above the volume 7k/6 the appropriate form was proved 

 to be 



r \ v + k) v + k 



which I propose to call the supra critical equation. 

 Between k and lk/6 we have the circacritical form 



pv 



M ( 1+J r-^s)-4 



V -B v — j3/ v + , 



This, then, gives the complete representation of ethyl oxide 

 in the fluid state if we establish the sufficiency of the infra- 

 critical form, as we now proceed to do. In the next table are 

 compared the pressures found by Ramsay and Young and 

 those given by the equation. 



Table XV.— Liquid Ethyl Oxide. 



Volume 



3-7. 



275. 



2-25. 



2. 



1-9. 





iq-o n /Pressure, exper. . 

 lJ ° °t „ calc. ... 



28 

 32 



29 

 26 



43 

 45 







-i*r Q p /Pressure, exper. . 

 ' \ ,, calc. ... 







19 

 14 



43 



48 





[ „ calc. ... 











19-5 

 20 



