102 Journal of the Mitchell Society. [June 



the pressure is considered the proportional error is very small. 



SP 

 When the -j-=: is considered the proportional error is large, 



and the values obtained from Biot's formula are too small. 



T "p 



3. The equation, , T7=- = p'i where // is the con- 



V d — p D 



stant of molecular attraction, is shown to be applicable with 

 exactness in the immediate neighborhood of and at the criti- 

 cal temperature for fifteen out of nineteen substances consid- 

 ered. The equation has already been proved accurate at 

 lower temperatures. 



It is shown that the constant of molecular attraction, /i, 

 can be calculated from the critical constants and the molecu- 

 lar weight. 



5. The known fact that the ratio of the theoretical to the 

 critical density is a constant for all substances is shown to 

 follow necessarily from the fundamental ideas and equations 

 upon which this series of papers is based. ' 9 



University of North Carolina, 

 April 3rd, 1905. 



