n is as follows: The piece is moulded normally, and it is
supported by a vacuum; but, at the moment at which, under ordinary
circumstances, it would be detached, the paste is made to ascend a second
time, when the first layer (already thick and dry) acts as a sort of
supplementary mould, and permits of increasing the thickness by about 2/5
of an inch. The piece is held, as at first, by vacuum, and the paste is
introduced again until the desired thickness is obtained.

Whatever be the care taken, accidents are frequent in both processes. They
are due, in general, to the irregular contraction of the pieces, caused by
a want of homogeneousness in the plaster of the moulds. In fact, as the
absorption of the water does not proceed regularly over the entire surface
of the piece, zones of dry paste are found in contact with others that are
still soft, and hence the formation of folds, and finally the cracking and
breaking of the piece. The joints of the moulds are also a cause of
frequent loss, on account of the marks that they leave, and that injure
the beauty of the form as well as the purity of the profile.

Mr. Renard has devised a remedy for all such inconveniences. He takes
unglazed muslin, cuts it into strips, and, before beginning operations,
fixes it with a little liquid paste to the interior of the mould. This
light fabric in no wise prevents the absorption of the water, and so the
operation goes on as usual; but, at the moment of contraction, the piece
of porcelain being, so to speak, supported by the muslin, comes put of the
mould more easily and with extreme regularity. Under such circumstances
all trace of the joint disappears, the imperfections in the mould are
unattended with danger, and the largest pieces are moulded with entire
safety. In a word, we have here a very important improvement in the
process of moulding. The use of muslin is to be recommended, not only in
the manufacture of vases, but also in the difficult preparation of large
porcelain plates. It is likewise advantageous in the moulding of certain
pieces of sculpture that are not very delicate, and, finally, it is very
useful when we have to do with a damaged mould, which, instead of being
repaired with plaster, can be fixed with well ground wet sand covered with
a strip of muslin.

_Drying of the Moulded Pieces._--When the moulded pieces become of a
proper consistency in the mould, they are exposed to the air and then
taken to the drying room. B