of
stout netting, carried on a vertical axis working through a stuffing-box,
which is fitted in the bottom of the outer or containing vessel or keir B.
The air can be exhausted from B by means of an air pump. A contains a
central division P, also constructed of netting, into which is inserted
the extremity of the tube R, after being twice bent at a right angle. P is
also in direct connection with the efflux tube E, E and R serving to
convey the dye or bleach solutions to and from the reservoir C. The
combination of the rotary motion communicated to A, which contains the
goods to be dyed or bleached, with the very thorough penetration and
circulation of the liquids effected by means of the vacuum established in
B, is found to be eminently favorable to the rapidity and evenness of the
dye or bleach.

* * * * *

ON THE MOULDING OF PORCELAIN.

By CHAS. LAUTH.

The operation of moulding presents numerous advantages over other methods
of shaping porcelain, for by this process we avoid irregularities of form,
twisting, and visible seams, and can manufacture thin pieces, as well as
pieces of large dimensions, of a purity of form that it is impossible to
obtain otherwise.

The method of moulding small objects has been described with sufficient
detail in technical works, but such is not the case with regard to large
ones, and for this reason it will be of interest to quote some practical
observations from a note that has been sent me by Mr. Constantine Renard,
who, for several years, has had the superintendence of the moulding rooms
of the Sevres works.

The process of moulding consists in pouring porcelain paste, thinned with
water, into very dry plaster moulds. This mixture gradually hardens
against the porous sides with which it is in contact, and, when the
thickness of the hardened layer is judged sufficient, the mould is emptied
by inverting it. The excess of the liquid paste is thus eliminated, while
the thicker parts remain adherent to the plaster. Shortly afterward, the
absorption of the water continuing, the paste so shrinks in drying as to
allow the object to detach itself from the mould. As may be seen, nothing
is simpler when it concerns pieces of small dimensions; but the same is
not the case when we have to mould a large one. In this case we cannot get
rid of the liquid paste by turning the mould upside down, because of the
latter's size, and, on another hand, it is nec