of Water at High Temperatures, 131 



774124= loe T , which, added to logP = 2-70285, gives 

 a 



0-44406 = log-, 



1 ■ P 



and thus — =2*758. This, multiplied by t l — t or «? 8, gives 



P 



Bd l ; and since ^ 



Sd Y :8d :: d Q t : t g, 



we have t g = 207 ; and since 

 ^ = 274 + 60-48, we have 

 *w= 127*5 and ^ = 246-5. 

 This gives the position of $• 

 on the axis of temperature. 



To find t x d v we multiply ^ = 246-5 by - =2*758, and set off 



P 

 the product 685 from the vertical scale of the chart as the length 

 of t l d l . Having thus found g and d v the chart line is drawn. 



Densities deduced from high tensions are generally less than 

 the true, in consequence of deviation from Mariotte's law, the 

 pressure increasing in somewhat less proportion than the density. 

 On this account the vapour-tensions taken below the boiling- 

 point are to be preferred infixing the direction of the chart line. 



§ 27. To find the upper terminal 7 of the chloroform line, we 

 have M. Pierre's observations {Ann. de Chim. October 1851, 



p. 208) to apply to the equation (7 — t) — = -j-, in which 7 is the 



unknown quantity. This equation is adapted to a series of dila- 

 tation observations with small range of temperature. It is to be 

 noted that those taken below the atmospheric temperature are 

 to be avoided as generally faulty (see figures appended to former 

 paper on Expansion). 



1590 CM. 



= 1619 C.A. . . . 



1-0187 



23-40 



23-79 . . . 



10276 





7-60 = ^ 



•0089= dv 

 10231= v 





*fP +t=zS S4P. 



dv 





Hence 



The two extreme observations at 0° and 62 0, 72 being com- 

 puted in the same way, give 7 = 329°. So this value is probably 

 not far from the truth. 



§ 28. In fig. 12 (PI. IV.) is presented a small chart with the 



K2 



