IMPROVEMENTS IN PIGMENTS AND IN THE MANU- FACTURE THEREOF
Year: 1876

page_text: LETTERS PATENT to Henry Knight, of Kingston-upon-Hull, in the County of
York, for the Invention of "IMPROVEMENTS IN PIGMENTS AND IN THE MANU-
FACTURE THEREOF."
Sealed the 4th July 1876, and dated the 7th January 1876.
PROVISIONAL SPECIFICATION left by the said Henry Knight at the Office of
the Commissioners of Patents, on the 7th January 1876.
HENRY KNIGHT, of Kingston-upon-Hull, in the County of York. * IMPROVE-
MENTS IN PIGMENTS AND IN THE MANUFACTURE THEREOF."
This Invention has for its object the manufacture of first-class pigments from
common and cheap materials,
1st. I dissolve zine) in hot dilute sulphuric acid; this can be kept hot during
the combination by circulating steam through coiled pipes therein, using a steam
jacket, or even injecting common or superheated steam or heated air. In this way
I get a hot saturated solution of sulphate of zinc.
2nd. In adding hydrochloric acid to calcium sulphide, result, precipitated sulphur,
and a solution of calcium chloride.
3rd. In precipitating zinc from a solution of its sulphate, nitrate, acetate, or
preferably its chloride, by means of sulphydric acid. To effect this the solution
must be kept distinctly alkaline. This I usually effect with the aid of ammonia
(afterwards recovered in any of the usual methods), result, pulverulent, hydrated
sulphide of zinc.
4th. In mixing in proper atomic proportions, calcium chloride obtained in part 2,
and zinc sulphide result, pulverulent calcium, sulphate, and solution of zinc
chloride.
5th. In taking precipitated sulphur of part or sulphur obtained from any other
source, and mixing it in atomic proportions with calcium sulphide to make
pentathionide of calcium mix with water and boil till nearly all is dissolved into a
red liquor.
6. In using the above red liquor (pentathionide of calcium and water (?) ), as a
precipitant of zinc from its solutions, result, hydrated zinc sulphide, and if sulphate
of zinc has been used calcium sulphide intermixed.
7th. In making the mineral kieserite ground to a powder, take the place of lime

page_text: salts above described. The mineral ground to a fine powder is shaken up with the
zinc solution.
8th. In taking any of these precipitates or preferably an intimate mixture of
them, and calcining them at a dull red heat, result, the base for paint required.
The hydrated sulphide of zinc I sometimes use without calcination.
*
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Knight in the Great Seal Patent Office on the 4th July
1876.
HENRY KNIGHT, of Kingston-upon-Hull, in the County of York.
MENTS IN PIGMENTS AND IN THE MANUFACTURE THEREOF."
"IMPROVE-
This Invention relates, 1stly, to the manufacture and production of sulphide of
zinc capable of being employed as a pigment, either alone or in conjunction with
sulphate of lime or with sulphate of baryta, and consists in the employment of a
saturated solution of sulphate of zinc at an elevated temperature in conjunction
with sulphuretted hydrogen or soluble sulphides of the alkalies or alkaline earths, by
preference pentasulphide of calcium.
In carrying out this part of my Invention I employ a hot solution of sulphate of
zinc or of chloride of zinc, or of mixtures of the same, which may be maintained at
an elevated temperature, either by circulating steam through leaden pipes contained
in the vessel; or by means of a steam jacket; or by the admission of steam into
the solution, and I pass into the solution sulphuretted hydrogen, so as to effect the
precipitation of the zinc as sulphide of zinc. Or to the heated solution of sulphate
of zinc I add a soluble sulphide of calcium or a solution of pentasulphide of calcium,
so as to effect the precipitation of the zinc as a sulphide and the lime as sulphate of
Jime in intimate admixture with each other. The precipitates obtained by either of
these processes are then collected and washed, and preferably submitted to a
heating or calcining process so as to render them more suitable for the manufacture
of paint.
This Invention further relates to the production of a pigment from salts of zinc
by addition to their solution (by preference sulphate and chloride of zinc, or of
chloride of zinc) of what is known as the mineral kieserite Mg S04 3(H2O), the
same being treated with an alkaline carbonate, whereby a carbonate of magnesia
is formed along with a carbonate of zinc, or the same resulting compound may be
formed by acting on a soluble zinc salt with the mineral magnesite M Co,; this
precipitate being afterwards submitted to calcination. Or instead of precipitating
the sulphide of zinc from a solution of sulphate of zinc I firstly decompose the
solution by means of chloride of calcium, or by means of barium, and then effect
the precipitation of the zinc as a sulphide by any of the methods herein mentioned,
the precipitated sulphate of baryta or of lime I mix with the sulphide of zinc
and employ the mixture as a pigment.
My favourite precipitant for zinc is a solution of pentasulphide or other
polysulphides of calcium in water, and is made in the following manner:-I take
calcium sulphide, a waste product at many chemical works, or lime, and boil it for
some hours with water and sulphur in such proportions that there be in it 40 parts
of calcium by weight to 160 parts of sulphur, the result being a reddish liquor which
is the precipitant required.
What I claim is,―
1st. The production of sulphide of zinc capable of being advantageously employed
as a pigment, by effecting its precipitation from a solution of sulphate of zinc at an
elevated temperature, either by means of sulphurretted hydrogen gas, or by means
of a soluble sulphide of an alkali or alkaline earth, such for example as the
pentasulphide of calcium in the manner as herein-before described.

page_text: 2nd. The production of a pigment by effecting the precipitation of zinc from
solutions by means of kieserite acted on by an alkaline carbonate, or by magnesite,
substantially as herein-before described.
In witness whereof, I, the said Henry Knight, have hereunto set my hand and
seal, this Thirtieth day of June, in the year of our Lord 1876.
Witness,
JOHN T. EMMETT,
Clerk to W. P. Thompson,
Patent Agent,
6, Lord St., Liverpool.
HENRY KNIGHT. (L.S.)