906 
In an analogous way we prepared also the Zinc-ortho-silicate: 
Zn‚SiO,. Also here the loss of Zn) during melting appeared to be 
by no means appreciable. Analysis of the used final product gave 
the following values: 
Observed : Calculated : 
SiO, 26.94 °/, DEO S a 
ZnO 73.12 °/, TTR 
In a series of experiments, in which the furnace-gradient was 
about 50—-54 M.V. per minute, we found with thermoelement // 
at the meltingpoint an E.M.F. of: 15667 + 5 M. V. (uncorr.). 
After reducing this value on the nitrogen-gasthermometer-scale (corr. 
—9 M.V.), this E.M.F. can be fixed at: 15658 +5 M.V., 
corresponding to 1509.°5 C. + 0°.5. 
On cooling, a feeble effect was observed under 14900 M.V.; but 
neither in this way, nor by sudden quenching of the heated mass 
by cold mereury, we could obtain any reliable result. According to 
STEIN *) the solidifying-temperature is 1484° C. 
The crystallised substance consists of irregularly bordered birefringent 
grains or seales; for the refractive-indices we found the following 
values: m, =1.719 :+:0.003::and n, =1.697 ‘+ 0.004. The bire- 
fringence is: 0.022. For the purpose of comparison we investigated 
again a natural Willemite (from Moresnet); the indices and the 
birefringence appeared to have the same values as the mentioned 
ones; so that there can be no doubt whatever, that the two preparations 
are identical. Also we had at our disposal a beautifully crystallised 
preparation obtained by Goreru*), which consisted of broad needles 
with rectangular extinction and positive birefringence. The refractive 
indices were: n,=1.720 + 0.003 and n, = 1.693 + 0,006; the 
birefringence was about: 0.027. So all these preparations evidently 
represent one and the same modification of Zn,Si0,, identical with 
the Willemite. 
§ 9. Cadmium-metasilicate: CdSiO, and Cadmium-orthosilicate : 
Cd, Si0,. 
From a hydrated, crystallised cadmium-nitrate pure Cd was 
prepared by heating, and from this the ortho- and meta-silicates 
were obtained by melting it with S¢O, in platinum-crucibles. 
1) Srei, Z. f Anorg. Chem. 55. 165. (1907). 
*) A. Goranu, Bull. de la Soc. Min. de France 10, 36, 264. (1887). We bring 
here once more our thanks to Prof. P. Gausert in Paris, who was so kind as 
to give us these preparations for our purpose. 
