304 
Jut as 12,5 is much greater than the normal value 7,1 for 
compounds, decomposition of the Se,-molecules into simple Se, atoms 
with greater attraction must necessarily have set in at 7% already. 
If « is the degree of dissociation of the Se,-molecules, 7, will be 
—2:(1+ 2), and 12,5 must still be multiplied by V(1-+-z). On the 
assumption that also for Selenium the attraction of the atoms is 
about 30.10-%, we have therefore for the determination of w: 
12.5V1+2—7,1(1—2) + 30e, 
from which 2=0,315 follows, so that Vaz, =12,49.10—-°X 1,147 = 
— 14,3.10-2, as Vide) = 1,147. 
In contradiction with v. WARTENBERG's statement |Z. f. anorg. Ch. 
56, p. 320 (1907) ], according to whom a perceptible decomposition 
into Se,-atoms would not set in before 2000° C., we find already 
a very pronounced dissociation at a little above 1000° C. 
Accordingly the above found value of aj, leaves us the alternative 
ny. — 6,2 or np =2:1,315 —1,5. According to what has been said 
the latter value is the more probable one. 
d. Tellurium. In 1880 Sr. Cramme Devine found for the boiling 
point 1390° C. = 1663° abs. Hence with the factor 1,36 (see for 
Selenium) 77, would become — 2260°. For 2y we calculate from 
this in approximation by means of our formula the value 27 — 2,807, 
hence y = 1,408. Hence 
3 
f= 807 |: — gn x 0.321 | — 2,807 (1 — 0,187°) = 2,281. 
rature determined by Jarcer (1999), viz. 452°,5 C. = 725°,6 abs. 
_KanrBauMm (1902) gives 6,235 for the density at the ordinary 
temperature‘). SPRING found 0,00003687 for the (linear) coefficient 
of expansion between 0° and 100°, which — extrapolated to 450° C. 
— would render the density at the melting-point about 5,94. From 
this “we calculate v/= 95,7 10°. With 7, = 2,28 the value 216 (10mg 
is then found from this for bj, whereas 255 .10~> was expected. 
Possibly the value of D, is taken too high, or that for f, and 7 
(through 7%) too low, just as for Selenium. 
With u, — 35,115 we get 
hire la 1,10. 
At last the value of Waz. With 6; = 235.10-5 we calculate 
from 7%: 
di 2460 285 LOR ee te Hage. 10 + mp7 
1) LENHER and Mora@an (1900) give 6,199; Kröner (Diss) values which vary 
between 6,27 and 6,10. 
En PEAR 
