681 
maximum value, amounted only to about 0,3 em°., which variation 
of volume corresponded with a displacement of the oil-level of 
+ 6 cm. in the capillary. 
With a purpose of determining the accurate situation of the tran- 
sition point the experiments described above were repeated several 
times, which resulted in a final determination of the transition point, 
which had been sought so long in vain, at + 202,8°, for at this 
temperature no variation of volume had taken place even after four 
days, whereas below it a diminution of volume and above it an in- 
crease of volume was observed. The inaccurate extrapolation which 
was mentioned before, and which gave 200,5° for the transition 
temperature, yielded, therefore, a result which was pretty near the truth. 
As we have always got the impression in this investigation that 
even on slow cooling of pure liquid tin exclusively or almost exclu- 
sively the tetragonal modification, which is metastable above 203°, 
is formed, and that even with pretty slow heating of the tetragonal 
form the conversion to the rhombic modification fails to appear, it 
seemed pretty certain that only the metastable unary melting-point 
of tin was known. To find the stable unary melting-point the curve 
of heating was determined of tin which had been heated for 48 
hours at 220° in a thermostat. The result yielded by this investi- 
gation and the particularities of the pseudo system derived from it 
will be communicated in a following paper. 
Anorg. laboratorium of the University. 
Amsterdam, Oet. 28, 1912. 
Chemistry. — “The phenomenon of double melting for fats”. By 
Prof. A. Smits and S. C. Bokmorsr. (Communicated by Prof. 
A. F. HOLLEMAN). 
(Communicated in the meeting of October 26, 1912). 
GutuH*), who has been extensively occupied with the preparation 
of simple and mixed glycerin esters of fatty acids, has observed the 
phenomenon of double melting for several of these fats. Thus we 
hear about tristearin that the crystallised tristearin has only one 
melting-point at 71°.5, whereas the tristearin that has first been 
melted, then cooled in a capillary, and then solidified, first melts at 
55° on supply of heat, then solidifies again, and then melts again 
at 71°.5 on further supply of heat. On the ground of these pheno- 
mena GuTH has come to the result that the melted and rapidly 
1) Z. f. Biol. 44, 78 (1902). 
