682 
cooled mass has not yet erystallised, and is therefore in a glassy 
metastable state. On supply of heat the metastable state would pass 
into the stable one, in which so much heat is liberated that small 
quantities are thereby completely melted, which later solidify again, 
but which melt again when the melting point has been reached for 
the second time on supply of heat. 
Kreis and Harner’) have repeated Gutn’s experiments and found 
them perfectly confirmed, but what rouses our great astonishment 
is this that they entirely concur in Gurm's view of the matter. 
Without entering into Gurn’s explanation, which is, putting it 
mildly, very improbable, we will state here very briefly what has 
been the result of an investigation which we have carried out with 
the purest tristearin of KAHLBAUM. 
It is clear from what precedes that in Gurm’s opinion the tempe- 
rature of 55° cannot he called a melting point of tristearin. Our 
experiment, however, has shown that GurH has stated the truth, 
in spite of himself, and that we have, indeed, to do here with two 
melting-points. It has namely appeared that the observed peculiar 
phenomenon is caused by the existence of two different crystallised 
wnodifications of tristearin, of which the metastable one appears most 
readily. The velocity of crystallisation of the stable form is still 
very small, even a few degrees below the point of solidification of 
the metastable form, and much smaller than that of the metastable 
modification. Hence when the liquid is cooled down to below the 
point of solidification of the metastable form, the latter is always 
made to erystallise. 
If the liquid is kept for some time at a temperature between the 
two melting-pomts, the stable form crystallises, but with a very 
slight velocity. 
If we start from the metastable modification obtained by compara- 
tively rapid cooling of the liquid, and if this metastable modification 
is placed in a bath the temperature of which rises slowly, the meta- 
stable unary melting-point appears at 34°.5; if the temperature of the 
bath is carried up to 63°, and if this temperature is kept constant for 
some time, crystallisation sets in slowly, and only after 2 or 3 hours 
everything has become solid and has passed into the stable modification. 
If the temperature of the bath is made to rise still further, the stable 
unary melting point occurs at 70°.8. The phenomena described just 
now have also been studied under the microscope, in which our 
views were perfectly confirmed in all respects. 
1) B. B. 36, 1123. 
