( 330 ) 



Waals for a — b (Contimiiteit p. 91) from Regnault's observations. 

 And so he obtained in KG. M. S. the equation 



p J^ —)(v—b)= 2262000 (l-J^ut) , 



Avhich he thouglit fit for detorniinint;' the deviation of the gases 

 from Ayogadro's law ^). 



In tlie ease of hydrogen we sliall however use Amagat's obser- 

 vations below 200 atm., which we have also used in determining 

 the pressures. With sufficient approximation they yield for the 

 isothermal of 0" C. 



p{v — 0,OOOG90) = 0,99931 2), 



when the normal volume is chosen as unit. Hence in order to 

 obtain the theoretically normal volume we must multiply the volume 

 at 0° and 1 atm. by 0,99931. 



From the weight of 1 liter of hydrogen : 0,08955 gramme at 0° 

 and 760 m.m. mercury, 0° C. and 45° latitude and the molecular 

 weight of CO3 : 43,89, we deduce the weight of a liter carbonic 

 acid to be 1,9652 gramme under the same circumstances ; Regnault 

 found for this 1,9771, which mc;ins a deviation of 0.0060 from the 

 theoretical value with respect to hydrogen. The density of carbonic 

 acid is therefore 0,0053 higher than the theoretically normal density, 

 so that in ordo' to find the theoretically normal volume of pure 

 carbonic acid we must multiply the volume at 0° and 1 atm. 

 by 1,0053. 



An observation made by Bkaun ^) gives us some information on 

 the deviations of Ayogadro's law shown by mixtures of carbo- 

 nic acid and hydrogen. He has found that when we mix two 

 equal volumes of hydrogen and carbonic acid under a pressure 

 of about 71 cm. mercury, the pressure rises 0,097 cm. thus 

 0,0014. And so we may accept that when taking two equal 

 volumes of hydrogen and carbonic acid we obtain by mixing a 



1) The problem in general hiis been treated by v. u. Waals in his conmiiinications 

 "On the accurate determination of the molecular weight of gases from their density.'* 

 Proc. Nov. '98 and "Variation of volume and of pressure in mixing II.'" Proc. Dec. '98 



") See Kamkrlikgh Onnes. Verh. Kon. Akad. v. Wet. ISSl. Algemeene theorie 

 der vloeistotien, p. 5 — 7. Abstract: Arch. Neerl. t. XXX. 



^) Wied. Ann., 34, p. 9i8, 1888. Kuj-;nen has pointed out a similar change of 

 pressure in mixing compressed gases by stirring. 



