475 
evaporating the solution obtained, 5. by melting iodine with a small 
excess of tin. The weighed out quantities were introduced in small 
portions into a glass tube and if necessary, heated a little to start 
the reaction; the tube was then sealed, heated for some time at 
250°, then placed vertically and cooled slowly. The orange-red cry- 
stalline mass obtained was then separated from the tin and the 
bottom layer of crystals and reduced to a fine powder. Both methods 
gave according to analysis, pure Snl, without any Snl, whatever. 
Found : 18,95—18,99 °/, of Sn; theory 18,99 °/,. 
For the preparation of Snl, is recorded a. addition of SnCl,-solu- 
tion to Kl-solution *) 5. dissolution of tin in concentrated hydriodic 
acid ?). 
The first method seems the most simple one. It has the disadvantage 
however, that in this reaction besides the red Snl,, double salts 
with KI may be formed also, whilst it is still uncertain whether 
a protochloro-iodide (Henry), or mixed crystals with SnCl, are per- 
haps obtained in addition. The first method was, therefore, aban- 
doned and the second process used instead. The action of tin on HI 
proceeds slowly and was carried out in a round bottomed flask 
attached to a refluxcondenser. The red crystals obtained ‘were dried 
in a vacuum desiccator, first for a few weeks over sticks of KOH, 
then for a few months over P,O;. Found 31,83 and 31,87 °/, of 
Sn; theory 31,92 °°/,. 
Another mode of preparation will be mentioned presently. 
3. The melting point of Snl, was found 143,°5, therefore in agree- 
ment with Emicnu, who gives 148°. 
The solidifying point determinations of I-SnI,-mixtures took place 
in the usual manner by cooling in the apparatus van Eijk. In order 
to prevent strong undercooling we constantly stirred with the ther- 
mometer during the cooling. 
The results are united in the subjoined table (p. 476) and 
represented graphically in Fig. 1. 
Hence we have a simple melting point line with a eutecticum at 
79°,6 and 60°/, by weight of SnI, (12,06 at. °/, Sn). 
4. In the preparation of SnI,, it had already been shown that 
SnI, could be heated for a- considerable time with Sn at 250° 
without any perceptible reaction setting in with formation of Sn 1, 
The possibility had, therefore, to be considered whether Sn and 
1) Bouttay, Ann. d. phys. et chim. (2) 34, 337 (1827); PERSONNE, 1. c. 
2) Personne lc. 
