474 
One of us has previously deduced the rule‘) that the meta- 
stable continuations of the branches ac and be must fall both 
together either within or without / Cu,,¢.HgCl,. Which case 
oceurs here is difficult to prove experimentally as both branches, in 
the vicinity of point c practically coincide with the sides of the 
angle Cu,.c.HgCl,. Moreover, the saturation line be of the HgCl, 
exhibits a very peculiar form. The metastable continuation must, of 
course, terminate somewhere on the side HgCi,—CuCl, of the tri- 
angle; from the course of the stable part in the vicinity of ¢, it 
appears, bowever, that this will not be possible without a point of 
inflexion appearing somewhere on the metastable part or on the 
stable part situated in the vicinity of c. 
Chemistry. — “The system Tin-lodine’. By Prof. W. Reinpers 
and S, pe Lane. (Communicated by Prof. SCHREINEMAKERS.) 
(Cummunicated in the meeting of September 28, 1912). 
1. Of tin and iodine two compounds are known, stannous and stannic 
iodide. As regards the preparation and properties of these compounds 
there exist in the literature different conflicting statements. By the 
older investigators’), for instance, it is stated that on heating tin with 
iodine, stannous iodide is formed. Herry ®), however finds a mixture 
of Snl, and Snl, and Personne *) Snl, only. The melting point of 
Snl, is given by Personne *) as 145° (solidifying point 142°), by 
Emica*) 143°. The boiling point according to Personne is at 295°, 
Emicn finds 341°. Henry, however, states that it sublimes at 180°. 
Of Snl, the melting point is given both at 246") and at a dull 
red heat (PERSONNE) and the boiling point both at 295°%) and at the 
temperature of molten glass (PERSONNE). 
For the knowledge of the binary systems of a metal and a metal- 
loid a renewed investigation was therefore desirable. 
2. Snl, was prepared in two ways, a. by treating granulated tin 
for some days with a solution of iodine in carbon disulphide and 
1) F. A. H. Scurememaxers, Die heter. Gleichg. von Baxuuis Roozeroom. Ill’. 268. 
2) La. Berzentus, Traité de chimie; Raumetsperc, Pogg. Ann. 48, 169. 
3) Phil. Trans. 135, 363 (1845). 
4) Compt. rendus. 54, 216 (1862). 
5). e. 
6) Sitzungsber. der K. Ak. v. W. Wien 118, IIb, 535 (1904) ( Monatshefte 25, 907. 
7) Conen, Abegg’s Handbuch d. anorg. Ch. IIL. 2, 571. 
