196 



Lord Kelvin on 



not only in the gaseous state (*001781) but also in the liquid 

 state (1*212)*. The latter of these is 681 times the former. 

 Now, all things considered, it seems probable that the crowd 

 of atoms in the liquid may be slightly less dense than an 

 assemblage of globes of diameter s just touching one another 

 in cubic order ; but, to make no hypothesis in the first place, 

 let qs be the distance from centre to centre of a cubic arrange- 

 ment of the molecules 681 times denser than the gas at 0° C. 

 and standard atmospheric pressure ; g will be greater than 

 unity if the liquid is less dense, or less than unity if the 

 liquid is denser, than the cubic arrangement with molecules, 



Col. 1. 



Col. 2. 



Col. 3. 



Col. 4. 



Col. 5. 



Col. 6. 



Col. 7. 



Col. 8. 



Col. 9. 



G-as. 



p 

 in terms of 

 grammes per 

 cubic centi- 

 metre. 



in terms 



of dynes 



per square 



centimetre. 



V 



in terms 

 of centi- 

 metres per 

 second. 



in terms 

 of (centi- 

 metre) -1 . 



Hence taking 

 2^=10*0 ($50) 



we have 

 s at 0° Cent, 

 in terms of 

 centimetres. 



Taking 

 iV=102u, 



m 

 in terms of 

 grammes. 



Mean free 

 paths ac- 

 cording to 

 Maxwell's 

 formula f 

 1 

 l ~ V2 . TrNtP 

 in terms of 

 centimetres. 



Eatio of 

 volume oc- 

 cupied by 

 molecules tc 

 whole volum 



CO., 



h; 



CO 



o 2 



Argon 



•001974 



•0000900 



•001234 



•001257 



00143 



•001781 



•0001414 



•0000822 

 •0001630 

 •0001635 

 •0001873 

 •0002083 



39200 

 184200 

 49600 

 49000 

 46100 

 41400 



89500 

 32900 

 61300 

 61600 

 57500 

 57700 



299 . 10" 8 

 1-81 „ 



2-48 ., 

 2-48 „ 

 2-40 „ 

 240 „ 



19-74. 10" 24 

 090 „ 

 1234 „ 



12-57 „ 

 14-3 „ 

 17-81 „ 



2-52 . 10" 6 

 6-84 „ 

 362 „ 

 3-64 „ 

 3-91 „ 

 3-89 „ 



1-340.10" 

 •311 „ 

 •799 „ 

 •799 „ 

 •724 „ 

 •724 „ 



regarded as spherical of diameter s, just touching. We have 

 681iY=l/fa*) 3 (3), 



and for argon we have by § 46 (1), 



M 2 = 57700 (4). 



Eliminating s between these equations we find 



iV=681 2 .57700y = 8-9.10 19 .2 6 . . . (5). 



If the atoms of argon were ideal hard globes, acting on one 

 another with no force except at contact, we should almost 

 certainly have q > 1 (because with closer packing than that of 



* See Kamsay and Travers, Proc. R. S., Nov. 1900, p. 331. 

 f Maxwell's Collected Papers, vol. ii. p. 348, eqn. (7). The 

 formula as printed in this paper contains a very embarrassing mistake, 

 x/2/r for V2 . v. 



