lour after standing for a few hours. Hence, the
observations should be confirmed by isolation of the crystals of
brommethylfurfural. No trace of this substance is obtained from the
xylose product.

In order to identify the substance, the ether extract, after
neutralisation, is allowed to evaporate to a syrup, and crystallisation
promoted either by rubbing with a glass rod, or by the more certain and
highly characteristic method of 'sowing' with the most minute trace of
omega-brommethylfurfural, when crystals are almost instantly formed.
These are recrystallised from ether, or a mixture of ether and light
petroleum, and further identified by the melting-point (59.5-60.5 deg.),
and, if considered desirable, by estimation of the bromine.

It is now found, so reactive is the bromine atom in this compound, that
the estimation may be accurately made by titration with silver nitrate
according to Volhard's process, the crystals for this purpose being
dissolved in dilute alcohol:

0.1970 gram required 10.5 c.c. _N_/10 AgNO_{3}. Br = 42.63
p.ct., calculated 42.32 p.ct.

This method of applying hydrogen bromide in ethereal solution is, of
course, unsuitable for investigations where a higher temperature has to
be employed, or where long standing is necessary, since, under such
circumstances, the ether itself is attacked. Wishing to make
investigations under these conditions, the authors have tried several
solvents, and, at present, find that chloroform is best suited to the
purpose. In each of the following experiments, 10 grms. of the
substance were covered with 250 c.c. of chloroform which had been
saturated at 0 deg. with dry hydrogen bromide. The mixture was contained in
an accurately stoppered bottle, firmly secured with an iron clamp, and
heated in a water-bath to about the boiling temperature for two hours.
After standing for several hours, the mixture was treated with sodium
carbonate (first anhydrous solid, and afterwards a few drops of strong
solution), filtered, and the solution dried over calcium chloride. Most
of the chloroform was then distilled off, and the remaining solution
allowed to evaporate to a thick syrup in a weighed dish.

The product was then tested for omega-brommethylfurfural by 'sowing'
with the most minute trace of the substance, as described above. It was
then warmed on a water-oven, kept in a vacuum desiccator over solid
paraffin, and the weight estimated. When necessary, the product was
recrys