( 396 ) 



/)j =: 28,9 and /^^ =^ '^''i'^l- If ^" equal iiuiiiber ui' iiioloculet) of car- 

 bonic acid and hydrogen so that ;(■■ =\ 2, are mixed in the same volume 

 r=0,03, the volume contains twice as many molecules, so the same 

 number in « = 0,015. For this volume Mr. Verschaffelt finds 

 p := 65. The value of ;>i + i>i — 05,21. 

 In the same way 



al t'=: 0,02s /), = 30,58 ;). = 38,97 ;), +/>; = 00,t5 and ;it (.• = 0,0J4 ;/^C'J,30 



// u=: 0,020 ^, = 32,40 i)„ = 42,04 /), +7)2=; 71,41 aud at u = 0,013 ;; = 74,20 



n = 0,024 ƒ), = 34,38 ;). = 45,05 />, +^2 = 80,03 ami at f = 0,012 ;; = 80,00 



„ » = 0,022 ;;, = 30,55 7)2 = 49,94 ƒ), -f/j. = 80,49 aud at ;; = 0,011 ;) = SC,75 



, = 0,020 ;), = 39,08 ;)j = 55,10 ;),+/). = 94,18 and at = 0,010 ;; = 94,40 



So in the case of carbonic acid and hydrogen, the quantity 

 «12—^12 (l+«0 is not large and («1 + «3 — 2 «i;) — {h^ -\- bc^ — 2 l^^^) 

 (1 +«0 small, but the contrary. The latter may be expected for 

 substances which difier much in physical properties. 



In my communications under the same title, in the proceedings 

 of November and December 1898, I have discussed two rules of 

 approximation for mixtures, viz. the law of Dalton and that of 

 Am AG AT. As a third rule of approximation the following rule might be 

 given : In a mixture a substance exercises the pressure that it would 

 exercise if the other molecules were substituted by molecules of its 

 own kind. Let us call the pressure wliich the first mentioned gas 

 would exercise, if all the molecules were of the same kind p], and 

 that of the second gas ps > then this rule of approximation conies 

 to the same as putting 



P —P\ (I — •'^) +P3* • 



From the graphical representation of Mr. Verschaffelt p. 329 

 it appears that for carbonic acid and hydrogen p— [y'i(l— *') + P2''j 

 is positive. 



From the characteristic equation we may deduce for this difference: 



„ , ,, ,(«l + «.-2ai3)-(6i + 63-2612) (l+«0 



v — v\i^ -*■) — Vi ''' = -Ki — •*■) ^^2 



b V 



for all volumes large enough that we may put 1 H for . 



V V — b 



So we see that for large volumes this third rule of approximation 



is exactly the same as that of Amagat. 



At a given volume p is a function of ■>■ of the second degree 



and the maximum deviation will be found at .*■ = ^'3 • 



