o artistic forms for the ornamentation of buildings, or
into slabs for roofing, facing, and other purposes. The subway from the
Exhibition to the District Railway is laid with the same material.

The works of the Wilkes Metallic Flooring Company are in the goods yard
of the Midland Railway Company at West Kensington. The Portland cement,
before it is accepted at the works, is tested by means of an Aidie's
machine. The general strain the set cement is required to bear is 750 lb.
to the square inch. All samples which will not bear a strain of 500 lb.
are rejected. The various iron slags are carefully selected, and rejected
when too soft, and at the works a small percentage of black slag, rich in
iron, is mixed in with them. The lumps of slag are first crushed in a
Mason & Co.'s stone breaker, and then sifted through 1/8 in., 1/4 in.,
and 1/16 in. wire meshes into these three sizes for mixing. Next the
granulated substance is thoroughly well washed with water to remove
soluble matter and impalpable dust, and afterward placed where it is
protected from the access of dust and dirt. The washing waters carry off
some sulphides, as well as mechanical impurities. The Portland cement is
not used just as it, comes from the works, but is exposed to the air in a
drying room for about fourteen days, and turned over two or three times
during that period. The slag is also turned over three times dry and
three times wet, and mixed with the Portland cement by means of water
containing 5 per cent. of "Reekie" cement to make the whole mass set
quickly. The mixture is then turned over twice and put into moulds; each
mould is first half filled, and the mixture then hammered down with iron
beaters. The rest of the composition is then poured in, beaten down, and
the whole mould violently jolted by machinery to shake down the mixture
and to get rid of air holes. While it is still wet the casting is taken
out of the mould, its edges are cleaned, and after the lapse of one day
it is placed in a bath, of silicate of soda. Should the casting be
allowed to get dry before it is placed in this bath, no good results
would be obtained; it is left in the bath for seven days. When delicate
stone carvings have to be copied, the moulds are of a compound of
gelatine, from the flexible nature of which material designs much
undercut can be reproduced. For the foregoing particulars we are indebted
to Mr. William Millar, the working manager at West Kensington. Som