IMPROVEMENTS IN THE MANUFACTURE OF CHROMATES, AND BICHROMATES
Year: 1864

page_text: PROVISIONAL SPECIFICATION left by Benedict Margulies and John
Knowles Leather at the Office of the Commissioners of Patents, with
their Petition, on the 24th December 1864.
We, BENEDICT MARGULIES, of Trieste, in the Empire of Austria, but now
residing at St. Helens, in the County of Lancaster, Chemist, and JOHN KNOWLES
LEATHER, of the same Place, Manufacturing Chemist, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
CHROMATES, AND BICHROMATES," to be as follows:-
The object of this Invention is to manufacture chromates and bichromates
in a more economical manner than is now commonly practised. To this end we
prepare a mixture of lime or of hydrate of lime or of other alkaline earths and
of chrome ore or of oxide of chromium (or of one or more of the impure com-
pounds of chromium) with or without one or more of the salts of soda or potash
and with or without manganese or other oxygen bearing material and with or
without silica or other difficulty fusible material (the use of which is to prevent
the mixture from fluxing when exposed to a strong heat) & we form the
same into blocks which we submit to the heat of a furnace until the chrome
ore or oxide or other compound of chromium is decomposed. The blocks we
prefer to make in the shape of the frustum of a cone. It is not necessary that
any of the substances aforesaid be pure, and they may be used in equal parts
by weight or in various proportions. From amongst the substances aforesaid,
we prefer to use equal parts by weight of hydrate of lime and sulphate of potash
and chrome ore reduced to a finely divided state, and after well mixing them

page_text: in any convenient manner to add water, and by kneading to bring the mixture
to the consistency of clay, after which we mould it into conical blocks. The
blocks thus formed we expose whether in a dry or moist state to the heat of a
furnace or oven, but by preference we use the hearth of a reverbertory furnace,
and subject the blocks to a heat gradually increasing from a low heat to a full
red heat or even to a white heat, being careful not to allow the heat to increase
so as to flux them, as in that case the mass would be very difficult to lixiviate.
The blocks are to remain in the furnace until the chrome or oxide of chromium;
or other compound of chromium has been either wholly or partially decomposed.
The blocks are then raked out and placed in any convenient vessel, and the
soluble compounds of chromium dissolved out either with water or with a
solution of one or more of the salts of soda or potash, and the liquor is treated
by any of the usual methods for the manufacture of chromates and bichromates
therefrom. If the mixture after lixiviation contains any undecomposed
chromium it is to be formed again into blocks either in the same state as it is
removed from the lixiviating vessels or after the addition of one or more of the
materials aforesaid, and again exposed to the heat of a furnace or oven as
before. We then extract the soluble compounds of chromium which may
have been formed within the furnace by lixiviation in the manner already
mentioned.
The Invention is also applicable to the production of chromates and
bichromates from any undecomposed chrome ore, oxide of chromium, or impure
salts of chromium contained in the residuary matter which remains after
lixiviation of the chrome charges operated on in the furnace by the ordinary
method, such residuary matter is to be treated in precisely the same way as
that last mentioned.