IMPROVEMENTS IN THE METHOD OR METHODS OF PREPARING CHROME YELLOW AND CHROME RED
Year: 1881

page_text: LETTERS PATENT to William Spence, of 8, Quality Court, Chancery Lane, in
the County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS
IN THE METHOD OR METHODS OF PREPARING CHROME YELLOW AND
CHROME RED." A communication from abroad by Emil Werner, of Warsaw,
Poland.
PROVISIONAL SPECIFICATION left by the said William Spence at the Office
of the Commissioners of Patents on the 3rd December 1881.
WILLIAM SPENCE, of 8, Quality Court, Chancery Lane, in the County of
Middlesex. Patent Agent. "IMPROVEMENTS IN THE METHOD OR METHODS OF
PREPARING CHROME YELLOW AND CHROME RED." (A communication from
abroad by Emil Werner, of Warsaw, Poland.)
This Invention relates in the first place to a new method of preparing chrome
yellow, which method is based upon the chemical action of a solution of dichromato
of potassium and sulphuric acid, or phosphoric acid, or even sulphate of alumina
upon whito lend or litbarge suspended in water and in a cold state.
The said solution or mixture intended to act upon the white lead is prepared by
mixing according to the particular shade of yellow desired, one half to two and a
half equivalents of sulphuric or phosphoric acid, or sulphate of alumina (in a
quantity adequate to the required portion of acid) with a solution of dichromato of
potassium in water, the said solution forming one equivalent to the other ingredients
before stated.
The suspended litharge to be acted upon as required is prepared by mixing one
part of white lead or litharge in ten parts by weight of water, grinding it into the
finest state, and sifting it through a very fine sieve, in order to separate the sand
and other heterogeneous matters.
The first described mixture of dichromate of potassium and a suitable acid is
then introduced into the tub containing the white lead or litharge in suspension,
the supply being arranged in a thin jet, in order to avoid the development of heat.
When the coloured matter has sunk to the bottom and the supernatant liquor

page_text: appears light yellow, the said coloured matter is taken off, washed several times
with water and filtered, whereupon it is ready for use.
And this Invention consists in the second place to a new method of preparing
chrome red, which method is based upon the process of boiling a suspension of
white lead or litharge in water, together with a solution of dichromate of potassium
in water, which may be soured with sulphuric acid.
For this purpose one equivalent of the white lead or litharge suspended in
water is boiled together with one half equivalent of the solution of dichromate of
potassium in water, to which solution one half equivalent of sulphuric acid may
be added if required. The boiling is continued till the filtered liquor appears light
yellow.
If the amount of dichromate of potassium be increased by a fraction of an
equivalent, the shade of the chrome-red obtained will come near to orange, and if on
the contrary it be diminished, the shade will become flesh-coloured.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Spence in the Great Seal Patent Office on the 3rd June
1882.
WILLIAM SPENCE, of 8, Quality Court, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN THE NETHOD OR METHODS OF
PREPARING CHROME YELLOW AND CHROME RED." A communication from abroad
by Emil Werner, of Warsaw, Poland.
This Invention relates in the first place to a new method of preparing chrome
yellow, which method is based upon the chemical action of a solution of dichromate
of potassium and sulphuric acid, or phosphoric acid, or even sulphate of alumina
upon white lead or litharge suspended in water and in a cold state.
The said solution or mixture intended to act upon the white lend is prepared by
mixing according to the particular shade of yellow desired, one half to two and a
half equivalents of sulphuric or phosphoric acid, or sulphate of alumina (in a
quantity adequate to the required portion of acid), with a solution of dichromate of
potassium in water, the said solution forming one equivalent to the other ingredients
before stated.
The suspended litharge to be acted upon as required is prepared by mixing one
part of white lead or litharge in ten parts by weight of water, grinding it into the
finest state, and sifting it through a very fine sieve, in order to separate the sand
and other heterogeneous matters.
The first described mixture of dichromate of potassium and a suitable acid is
then introduced into the tub containing the white lead or litharge in suspension,
the supply being arranged in a thin jet, in order to avoid the development of heat.
When the colouring matter has sunk to the bottom, and the supernatant liquor
appears light yellow, the said colouring matter is taken off, washed several times
with water and filtered, whereupon it is ready for use.
And this Invention relates in the second place to a now method of preparing
chrome red, which method is based upon the process of boiling a suspension of
white lead or litharge in water, together with a solution of dichromate of potassium
in water, which may be acidulated with sulphuric acid.
For this purpose one equivalent of the white lead or litharge suspended in water
is boiled together with one half equivalent of the solution of dichromate of potassium
in water, to which solution one half equivalent of sulphuric acid may be added if
required. The boiling is continued till the filtered liquor appears light yellow.
If the amount of dichromate of potassium be increased by a fraction of an
equivalent, the shade of the chrome red obtained will como near to orange, and if
on the contrary it be diminished, the shade will become flesh coloured.
Having thus described the nature of tho said Invention, and in what manner
the same is to be performed, communicated to me from abroad as aforesaid, I
hereby declare that what I claim as of the Invention is,―
First. The method of preparing chrome yellow as described.
And, Secondly, the method of preparing chrome red as described.
In witness whereof, I, the said William Spence, have hereunto set my hand
and seal the Second day of June in the Year of OUR LONÌ One thousand
Witness,
W*. H. SPENCE,
8, Quality Court,
Chancery Lane.
WILLIAM SPENCE. (L.s.)