( 580 ) 



, Tdp\ l-ii.-/i 0,0163 ^ ^ _^ ^ ^.^ 



r = - ^ r= 4 i^-'-'- = 4 X = 4 X 1.136 = 4.545. 



^ pdTJi. l_/?^-4,t ^0.8068 



.Jnsl as A comes auaiii xci'v close lo llic normal xaliic 0,375, so ]" 

 f'oi* Indrou'cii a|)|ti'oacli('s auaiii close lo llic llieorelical \aliie 4. 4Mie 

 ex[)i*essioiis tor 7'/.. aiid jij- (liller oiilv little tVom those, tbiiiid for 

 these (|iiaiilitics for ti'i-atomic gases, such as ('O,,; the e\|)i*essioii f(»r 

 /•/. on the othei' hand deviates stroii,ulv tVom it. This is to he ascribed 

 to the fact, that l),j has here not the \alne of neai'lv four-times A,,, hut 

 amounts to oidv twice that \alue. l"he (|uantilies (■^^ and ,■?„ are there- 

 fore much Mualler than in the case of tri-alomic «iases. 



VAN DKH AVaai.s h>mid foi- CO., e.,u-. ,-?, =0,I3(S and ji = 0,1. the 

 \alues we foimd altoxc aniounlin,t>' to oidv about one liiird of these 

 \alnes. I>i; is also in this case not O.iSt) A,, biii 0,1)2 />,,, and for r/,- we 

 find 'ISu Itjc instead of 2,03 A/,., or 2,37 A,, instead of 1,75 A,,. 



It is certaiidv of the hiuhest importance to know whelhei- the 

 result lor /•/; aurees w idi the experiments. At the same lime the \alne 

 of the critical coëflicient A \\ ill then agree, for the values of 7/. and 

 pk agree verv well. Ihit with the in\(^stigalion of this (|nesti()n, and 

 Avilh the \-ei-iticaIioii of )', we will wail till we haxc investigated 

 the behavioni' of h at higher temperature, which w ill be done in the 

 next cha|tter. 



1\'. In the tii-st place \\'e will repeal the calculations of § 2 at 

 DIP, 25 V. We deri\-e the following table (p. 5<S|) from the expe- 

 riniejits of AMA(rAT ') at that lem|>erature. 



/' — I) has here beeji calculated from 



0,9994 (1 ^ 99.25 X 0.0036627) 1.3627 



p + ~, /' 4- -., 



V V 



For the "calculated" values of /> 1 determined cpute in the same 

 wav as is indicated above for : 



/,., = 917 ; A„ = 386 . 



Again the initial \alues of /> "found" (up to about 400 atm.j are 

 t(»o great. Ihit afterwainls the agreement is suflicient, though the 

 \erilication ^\ as onlv possible up to 1000 aim., as, alas, no fiuihei' 

 experiments were available. We come !o the remarkable result, that 

 the value of />„ has considei-ablv deci-eased though the limiting value 

 of A has remained unchanged. It seems that at higher tem])eratnre 

 the atoms in the molecule mav approach one another closer than at 

 lower temperature. 



1) 1. c. p. 38 (:2"'l iiirlfod). 



