tallised from ether, and further identified by the tests
mentioned. The following results were obtained:
Weight of
crude residue.
Swedish filter paper 3.0 crystallised at once by 'sowing.'
Ordinary cotton 3.3 " "
Mercerised cotton 2.1 " "
Straw cellulose[6] 2.3 " "
Laevulose 2.2 " "
Inulin 1.3 " "
Potato starch 0.37 " "
Cane sugar 0.85 " "
Dextrose 0.33 uncrystallisable.
Milk sugar 0.37 "
Glycogen 0.34 "
Galactose 0.34 "
The products from _dextrose_, _milk sugar_, and _galactose_ absolutely
refused to crystallise even when extracted with ether and again
evaporated, or by 'sowing,' stirring, &c.
The _glycogen_ product deposited a very small amount of crystalline
matter on standing, but the quantity was too minute for examination;
moreover, it refused altogether to crystallise in contact with the
aldehyde. It may fairly be stated, therefore, that these last four
substances give absolutely negative results as regards the formation of
omega-brommethylfurfural; if any is formed, its quantity is altogether
too small to be detected.
The specimen of _starch_ examined was freshly prepared from potato, and
purified by digestion for twenty-four hours each with _N_/10 KOH, _N_/4
HCl, and strong alcohol; it was then washed with water and allowed to
dry in the air. It will be seen that this substance gave a positive
result, but that the yield was extremely small, and might yet be due to
impurity. Considering the importance of the behaviour of starch, for the
purpose of drawing general conclusions from these observations, it was
thought advisable to make further experiments with specimens which could
be relied upon, and also to investigate the behaviour of dextrin. This
the authors have been enabled to do upon a series of specimens specially
prepared by C. O'Sullivan, and thus described by him:
1. Rice starch, specially purified by the permanganate method.
2. Wheat starch " " "
3. Oat starch, contains traces of oil, washed with dilute KOH
and dilut
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