478 
The analysis of the Sn l, thus prepared gave 31.6 and 31.2°/, of 
tin instead of the theoretical quantity (31.9). 
5. The melting point of Snl, was determined by heating and 
cooling in a small electric furnace consisting of a cylindric little pot 
of porous earthenware, surrounded by a nickel heating wire and 
placed in a similar larger pot which was then filled up with asbestos. 
The melting point was found at 319°—320°. 
The boiling point of Sn I, was determined in a 25 em. long hard 
glass tube 3—4 em. in diameter, the upper part of which was 
thoroughly isolated by a thick layer of asbestos and could be heated 
electrically by a nickel wire, whilst the lower part, which contained 
the SnI, was heated strongly either electrically or with the blow- 
pipe. The temperature was measured with a standard Pt-PtRh 
thermocouple. 
The mean of many determinations was 720°. 
6. Addition of SnI, or Sn had no perceptible influence on the 
melting point of SnI,. These substances, when by the side of 
Sn I,, form a second liquid phase, so that above 320° there are two 
regions of decomposition, one between SnI, and Sn I, and one be- 
tween Snl, and Sn. The fused Snl, lies in a narrow region of 
homogeneous mixing. 
In order to determine the limits of these regions of decomposition, 
Sn I, and SnI, were heated in a narrow sealed tube and shaken for 
an hour at 350° in an electric tube furnace. The apparatus was 
then placed in a vertical position, the tube was removed and rapidly 
cooled in a current of air. The solidified Sn I, and Sn I, layers were 
separated from each other, well scraped and then analysed. 
The SnI, layer. The total tin content was 18.95 and 19.02, mean 
18.99, which corresponds to pure SnI,. The solubility of Sn [, in 
Sn I, is therefore, practically il. This result was confirmed by 
dissolving a portion of the upper layer in carbon disulphide and 
after adding iodine, titrating the excess of the latter with sodium 
thiosulphate; only 0,06 °/, of Sn I, was thus found. 
The SnI, layer. The total tin content amounted to 31.2 and 
30.9°/,, mean 31.1°/,; SnI, requires 31.9°/, of tin. This analysis 
therefore points to a 6°/, SnI, content. This figure must probably 
be considered as a maximum. During the fusion the Sn I, penetrates 
between the glass and the SnI, layer so that after cooling, this is 
enveloped by a thin layer of Sn I, which might be not completely 
removed in some places. The fact that addition of SnI, does not 
