1052 



It may appear from the following table with what accuracy the 

 value of the quantity -/k is oiven by this simple formula. 



This table requires sonne elucidation. Of the many substances whose 

 values were at my disposal. 1 have only chosen some typical ones, 

 namely those .substances which, just as in the table in I, p. 819, 

 represent a class as far as the value of y/, is concerned. Oxyg;en 

 has not been inserted, because we know^ already from I, p. 819 

 that according to the values of .v and ƒ found for 0., the value 

 of 7/t would have to be about 0,72, whereas 0,813 was found, just 

 as for Xenon. We have ascribed this to association. Also for CO^, 

 which belongs to the class of acetylene, the formula yields too low 

 a value of yi-, ^'iz- 0.85, whereas 0,9 was found. Whether here too 

 association of the liquid is the cause, is unknown to me. To the 

 iso-pentane group belongs also n-pentane and other substances, of 

 whicli 7'/, lies in the neighbourhood of 460° or 470° (absolute), 

 and y in the neighbourhood of 0,90 or 0,92, For iso-pentane yk = 0,91 fi 

 according to Young. The value given by us in the table, viz. 0,914, 

 is a mean value. Also CbH^, CCl^, and such substances with Tk in 

 the neighbourhood of 550° or 560° absolute, and y/, = 0,9^-J or 0,94 

 belongs to the Fluorbenzene group. The given value 0,933 is again 

 a mean value. 



For H,0, of which T^. = 638, 1/7^ = 25,26, a value 0,98 would 

 follow for yA; (2y^- — 1=0,96). It is unknown to me whether expe- 

 rimentally a sufficiently established value of yk for water is known ; 

 })robably it \\'\\\ again be greater than 0,98, because also H^O is 

 associated, although it be at lower temperatures than the critical. 



Even foi' a sul)slance with a critical temperature of 900° y/, would 



