In every vertical column the increase is therefore 55 units, while 
in every horizontal row the decrease amounts to 15 units. The 
values for Si, As, and Te, which we have placed between paren- 
theses, could not be verified as yet by known compounds, the critical 
data of them being imperfeetly known. 
Fundamental Values for a k XK 102. 
| | | He = 0,8? 
| C=31 | N =2,9 | O =21 |F =2,9? | Ne = 2,0? 
= P =64 |S =63 | Cl =5,4 || Ar =5,2 
A, ee Arse it (ae eg Ihre bo 
ee re SD ee dB IN a Oe 
If we add to this Hg = 11,0, as we shall immediately find, it 
may be said that in the different horizontal principal series of the 
periodic system the values of a are very nearly constant, the ratio 
in round numbers being (taking He = 1) 
MESMER "on esa ae 
We add that the values of 4 in the column of the halogens are 
in exactly the same ratio as the values 1: 2:3: 4 (taking Cl = 110). 
II. Before proceeding to the calculation of some new funda- 
mental values — in which some methods will be discussed for the 
calculation of the values of « and 5 for substances where 7). and 
pr are unknown, and besides of the unknown values of 7; and 
pr themselves — we will make a few general remarks. 
In the first place we draw attention to this, that when the above 
tables are used to calculate the critical temperature and pressure 
for elements, the critical data of which are unknown as yet, the 
molecular state of these elements at 7’. must be taken into account. 
Thus at the eritical temperature mercury has long become He. 
Only at lower temperatures the mercuryvapour is—= Hg, on account 
of the great volume, as is known. But at higher temperatures, where 
the vapourvolume gets smaller and smaller, the association to Hg, 
increases more and more, and is almost complete at 7%. For mer- 
cury, namely, just as for some other associating substances the 
increase of volume of the vapour triumphs on the decrease of tempe- 
rature, and therefore the association does not increase, but decreases. 
The same thing is probably the case for water, but for this 
substance the association at 7%. (of the vapour namely) is still slight, 
