( 1-^9 J 



licterogoneous molecules wliich cannot pass into one another. Here 

 Iiowever we are dealing witii molecules wiiich can pass into each 

 other. And if in such a case ' the establishing of the equilibrium 

 requires a long time, then we nuist account foi- the fact tluit in this 

 case more-atomic molecules oidy slowly conform tlieir size to the 

 varied circumstances, though in other cases thev can bring tiieii- 

 internal motions so quickly into harmony with, for instance, a variation 

 of the temi)erature. 



I tlierefore think it not to be proved, that the increase of h being 

 either a real or a quasi increase, requires a noticeable time to be 

 brought about, till the real constancy of the temperature throughout 

 the closed vessel aiul the perfect purity of the substance has been 

 proved, which as yet is not the case. 



It must be granted that the summit of the boundary curve is 

 broadened and flattened b}^ the variabilit}' of h and that the critical 

 isothermal may be estimated to have a lai-ger part which is nearly 

 parallel with the r-axis. And this causes considerable differences 

 of density to follow from small differences of pressure. But if no 

 causes even for small differences of pressure can be pointed out, 

 then the occurrence of differences of density larger tiuxn those that 

 follow from the action of gravity Q.m\no\ ax q\\ ho, nixWQé. phenomena of 

 retardation, these latter being also a kind of phenomena of equilibrium. 



Anotlier obser\'ation of general nature before I conclude at least 

 for the present these considerations on the influence of the variability 

 of h. This variability accounts for the possibility of deviations 

 from the law of corresponding states. If the way in which h varies 

 with the volume is different for different substances i.a. in conse- 

 quence of a different ratio of bg and h^, then the general course 

 remains the same, but the isotliermals become different in details. I 

 have even begun to doul)t whether the behaviour of substances 

 containing the radical OH in the molecule — acids, alcoiiols, water 

 etc., wliich in gaseous state present no association to double molecules 

 and which are often indicated by the name of abnormal substances 

 — wliich behaviour deviates so markedly from diat of other sub- 

 stances, must really be ascribed to assoeiation of the molecules in 

 the liquid state. 



In connection with equation (6) (see p. 143) the question arises : Is the 



on 



quantity which 1 have denoted by -r— for these sul)staiices perhaps 



small? Is the easy substitution of one of the components perhajis an 

 indication of a feeble connection of the parts of the compound which 

 involves a strong variability of the size of the molecule. The so called 



