477 
370 
360 
350 
340 
330 
320 
310 
300 
290 
280 
270 
260 
250 
240 
230 
220 
210 
200 
190 | 
180 
170 
160 
150 
140 
130 
120 
110 
100 
90 
80 
70 
J 2 4 6 81012 14 16 18 2022 24 26 28 30 32 34 at. % Sn 
Sn Iq Sn la 
Fig. 1. 
left ‘on evaporation. Prrsonne allowed but a short time for the 
reaction and took no particular care to accelerate the same by 
addition of an excess of fine tin powder, and so he got no appre- 
ciable quantities of Sn I,. 
By this conversion is now indicated also another method for the 
preparation of SnI,, namely, prolonged heating of Sn + Snl, in a 
sealed tube at a high temperature (360°). 
It appears that Sn I, and Sn I, then form two liquid layers, a bottom 
layer of Sn I, and an upper layer of SnI,. In vrder to promote the 
reaction it is, therefore, necessary to keep on shaking the tube so as to 
bring the Sn I, into contact with the Sn. By placing the tube, at the end 
of the heating operation, in a vertical position, and then allowing it to 
cool, we obtain, after solidification a crystalline stick which can be 
readily removed from the tube and breaks up along a fairly sharp 
meniscus into a Snl, and a Snl, piece. By strongly heating in a test 
tube of hard glass, the Sn I, can be freed from the adhering Sn I,. 
