314 
dissociation, so that for the calculation of « we shall have: 
9,22V1 + 3e =7(l — 2) + 302, 
giving «0,205, hence V(1+32r)=1,271, and Va, = 9,22 .10-2_~ 
x 1,271 = 11,72.10-. In this it should be observed that when 
the attraction of the isolated atoms should be greater instead of 
30.102, the value of a will be found smaller; also in the case that 
the normal attraction of As in compounds should be greater than 
i Ore 
If really Va, is =11,72.10-2, then follows for the critical 
pressure : 
Pk == zo (ol = wi : eae Ne As = 125,2 atm., 
aan 5) 28 X 380,25. 10—8 
in agreement with the value calculated above from the vapour 
pressures *). 
We may now proceed to give the calculation of a few Arsenicum 
compounds, viz. of AsH, and AsCl,. 
thing would have been converted to As; — in virtue of the comparatively high 
value of x (the degree of dissociation As, As)), viz. 0,2. 
1) From the vapour pressures determined at 557° and 600° C. we calculate 
namely easily (see Paper Il) Fo X Tr = 5727, Fo + log” pr =9,8270 (in which 
pk is expressed in mm.). Further follows from this and from the equations 
Tr =786nk Kak: bk, Pk = %Yog6 Kak: be, Vak = (T+ 23x). 10 -2, in which 
( =0,97, bx =195.10 5, ne = 4:(1+32z) and pk in atm, the perfectly accurate 
values 
f= 13516? abe, pp = 124,6 atm Ps 4,351 t/o — 11,69. FOR 
ze = 0,2041 
through a calculation of approximation for the five unknown quantities 7% , pk , 
Fio,ak and a. 
For pz we found in round numbers 125 atm.; for 7% 1320° abs. If we take 
1316°, the somewhat higher values 4,39, 4,51, 4,58, 4,59, 4,57, 4,54, 4,47, 4,42 
4,35, 4,35, 4,31, 4,35 are found for the values of Hg corresponding with the 
different vapour pressures, so that we duly find 4,35 for the 9th and 12th values 
in agreement with what precedes. 
We may add that 7% and px (in atm.) are connected through the equation 
Tr = 5727 : (6,4462—log!" px). Further evidently pk X (28 bx? : §)=( 74-282). 10-4, 
Th X (bk : 785) = 4 (TH23x 2. 10-4 (1+32), so that after elimination of 7% and 
pk the following equation remains : 
MT 4232). 10-4 780 
3e bet ot 
or also: 
ee a 
5727: 6,462 log’) (7-4 280)" 107+ = ae 
= 369,0 : [6,4866 — log'® (7 +232)" |, 
from which then « = 0,2041 ás calculated. From this log'® pj = 2,0955, pr = 124,6. 
Etc, Etc. . 
