( 557 ) 

 TAÜl.E XVI. 



June '02 \\\o iiiaiiönieier was luit seldom used, and the pressure 

 during lluil lime was low, while the pressure in (he monlhsJune — 

 Aug'uslus '02 was oflen and dui-inu' a long' linu' from GO lo 125 

 almospheres. IIcMiee il s(>ems that this \arialiou is much grealei- at a 

 liigli than at a low pressure. 



A similar \ariation of an air manometer with the time, probat>l\ 

 owing to the ahsoi'ption of oxygen in the niercnrv, lias also been 

 noted \)\ Ktknkn and RoissoN (Phil. Mag. Jan. '02 p. 150). 



In the mixtm-es of the molecular proportions 0.1 and 0.2 of 



oxygen the vai'iations of the noi-mal volume were less than In 



1000 



those cases we ha^•e acce}ite(l for the normal volume the mean 



of the vahies before and after the measin-ements. 



On the other haiul, in a mixture with a molecular pi'oportion of 

 0.3072, w Inch for some weeks had uninterruptedly been exposed to 

 high pressure, the normal volume of 72.878' cc. before the expe- 

 riments (15 June '03) had fallen to 70.980 cc. after the e\))ei'iments 

 (13 Ang.). It being highly ])robable that the variation of the normal 

 volume involves a considerable variation in com{)osition, the results 

 of the measui-emenis with this mixture which with regard to the ejid 

 condensation jji-essnres and vol tones extended to — 14''.7 C., will 

 not be given hei'e. 



This also shows how very imporiant it is that we should be 

 able to delei-mine the iu>rmal xolume aftei- the measurements '). 



From the observation of the \'olume occupied \)\ the gas at a 

 temperature of about 20 ('. and a pressure of about 1 atnios|)hei-e 

 we derived the volume which the gas would occupj)y at 20' C and 

 1 atm. (75.9467cm. mercni-y at Leiden, com|). ('omm. N".70, These Pi-oc. 

 l\'June29, 1901. p. 111). Use was made of the coefficient of jtressure 

 \ariation given in this ('omm. II, p. 553, and (he law of Hoyi,k 

 was ap|)lied. \\\ multiplication by the \alues of the coefticienfs 

 A K.iu giNon in table XI\' p. 554 under ( \ we lind from this the 

 volume which the gas would have occupied if from an inlinilelv 



1) Coiiip. Oomiii. i\". .'.o. Tlitsc Fiuc. II .liiue is'j'J. p. 2'J, and N". 70. V. 

 Ihese Proc. IV, June ii9, 1901, p. 107. 



