Physics. — “On the Additivity of the Values of b and Va of 
the Equation of State, and on the Fundamental Values of 
these Quantities for Different Elements, in Connection with 
the Periodical System”. By Dr. J.J. van Laar. (Communicated 
by Prof. H. A. Lorenz). 
(Communicated in the meeting of Jan. 29, 1916). 
1. Introduction. 
The additive qualities of the quantity 6 of the equation of state 
have already been pointed out by Prof. v. p. Waats'), particularly 
as far as the elements C, O, H and Cl are concerned. I have 
extended this research over many other elements, in which remark- 
able regularities have come to light with regard to the fundamental 
values of } for the different elements in connection with the pervo- 
dic system. 
In reference to the values of a Van Der Waars mentions nine 
Papers by Marnrews*), adding that this writer bad come to “very 
remarkable” relations with respect to these values. ““Remarkable” 
Maruews’ assertions decidedly are — but in an entirely different 
sense, I am sorry to say, from that probably meant by VAN DER 
Waars. From the critique which I have ventured to give in the 
following paper on Maruews’ treatises, it will be clear to the readers 
that Marnews’ views and the rule at which he thinks he has arrived, 
lack every sound foundation. 
On the other hand | have found that also the values of p/a are 
perfectly additive, and that here too we meet with striking regula- 
rities with regard to the periodic system. 
But there is more. In this I have found that in all cases, in which 
the central atom — e.g. C in CH,, CCl,, CHCI,, C,H, ete. etc., Ge 
and Sn in GeCl, and SnCl,, N and P in NH, and PH, — is entirely 
surrounded on all sides by other atoms or atom groups, the attrac- 
tion of this central atom to the outside on other molecules entirely 
vanishes. That namely the lines of force of the attracting (cohesive) 
1) These Proc. of Febr. 28 1914, p. 880. See also ibid. March 28 1914, 
p. 1076 and my treatise These Proc. XVII p. 598. This additivity itself was 
already long known, bowever. Cf. among other things Guyr Dissertation, Paris 1892). 
fterwards Barscuinsx1 (Zeitschrift für physik. Chemie 82, p. 87 (1918) ) found 
at Te, reduced to our unities, H = 67, 0 = 139, C= 114, all X 10—5. These values 
are, however — particularly those for H and O — quite erroneous (see our 
table in § 3). 
2) Journ. of Phys. Chem. 1913. 
