A Process for the Production of Blue Ultramarine from the Material known as Green Ultramarine.
Year: 1892

page_text: Date of Application, 28th Oct., 1892-Accepted, 28th Oct., 1898
COMPLETE SPECIFICATION.
A Process for the Production of Blue Ultramarine from the Material
known as Green Ultramarine.
We RALPH WALDO EMERSON MAC IVOR Analytical and Consulting Chemist
and ALEXANDER CRUICKSHANK, Gentleman both of Portland House, Guildhall,
in the City of London, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
Green ultramarine, which may be manufactured by any known process, is boiled
or digested under pressure, in a closed vessel, in a solution of sulphide of sodium
which has previously been saturated with sulphur, or the green ultramarine is first
mixed with sufficient sulphur to saturate the sulphide of sodium solution in which
the mixture (ie. the green ultramarine and sulphur) is subsequently digested-this
quantity of course, depending on the quantity of sulphide of sodium in the volume
of liquor employed, but the proportions between the sulphur in the mixture and
the sulphide of sodium in solution will be in the ratio of 39 to 64 these being
equivalent proportions.
The proportions we employ when working on a commercial scale are
The operation of boiling may be carried out in an iron pressure boiler or other
suitable apparatus and its duration need not exceed eighteen hours in any case, the
time being dependent on the quantity of green ultramarine under treatment and also
on the tint desired.
The sulphur liquor should be so proportioned to the green ultramarine that it
forms a thin cream with the green ultramarine.
When the mass within the boiler has obtained the desired tint it is run into
covered settling tanks where the ultramarine is allowed to settle and the supernatant
liquor run off; or the mass is run through a filter press which separates the solid
pigment from the liquor.
.
The blue ultramarine is thoroughly washed with water and dried in the
ordinary way.
The strength of the sulphide solution depends upon the quantity of green
ultramarine under treatment in a given volume of liquor, but in no case will it
be less than one per cent. or more than twenty per cent., varying according to
circumstance between these points.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The production of blue ultramarine from green ultramarine by mixing the
green ultramarine with sulphur and boiling or digesting the mixture under
pressure, in a closed vessel, in a solution of ordinary sulphide of sodium substan-
tially as described.
".
2. The production of blue ultramarine from green ultramarine by boiling the
green ultramarine under pressure, in a closed vessel, in a solution of sulphide of
sodium which has been saturated with sulphur substantially as described.

page_text: 3. The production of blue ultramarine from green ultramarine substantially in
the manner described in the foregoing Specification.
Dated this 28th day of October 1892.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, Agents.