operation of which is very irregular.

The operations embraced in the manufacture of this kind of fuel are as
follows:

The refuse is sifted in order to separate the dust from the grains of
coal. The dust is not submitted to a washing. The grains are classed
into two sizes, after removing the nut size, which is sold separately.
The grains of each size are washed separately. The washed grains are
either drained or dried by a hydro-extractor in order to free them from
the greater part of the water, the presence of this being an obstacle to
their perfect agglomeration. The water, however, should not be entirely
extracted because the combustibles being poor conductors of heat, a
certain amount of dampness must be preserved to obtain an equal division
of heat in the paste when the mixture is warmed.

After being dried the grains are mixed with the coal dust, and broken
coal pitch is added in the proportion of eight to ten per cent. of the
coal. The mixture is then thrown into a crushing machine, where it is
reduced to powder and intimately mixed. It then passes into a pug-mill
into which superheated steam is admitted, and by this means is converted
into a plastic paste. This paste is then led into an agitator for the
double purpose of freeing it from the steam that it contains, and of
distributing it in the moulds of the compressing machine.

[Illustration: IMPROVED MACHINE FOR COMPRESSING REFUSE COAL INTO FUEL.]

Bilan's machine, shown in the accompanying cut, is designed for
manufacturing spherical conglomerates for domestic purposes. It consists
of a cast iron frame supporting four vertical moulding wheels placed at