A NEW OR IMPROVED MANUFACTURE OF PAINTS OR COLORING MATTERS
Year: 1878

page_text: LETTERS PATENT to Henry Knight, of Ryde, in the County of Southampton,
for the Invention of "A NEW OR IMPROVED MANUFACTURE OF PAINTS OR
COLORING MATTERS."
Sealed the 21st June 1878, and dated the 9th January 1878.
PROVISIONAL SPECIFICATION left by the said Henry Knight at the Office
of the Commissioners of Patents on the 9th January 1878.
HENRY KNIGHT, of Ryde, in the County of Southampton.
MANUFACTURE OF PAINTS OR COLORING MATTERS."
"A NEW OR IMPROVED
My Invention consists in the manufacture of paints and coloring matters or
pigments from the colored or ferruginous sands and colored sandstones found in the
Isle of Wight and in other places in the United Kingdom.
I have discovered that these sands and sandstones when suitably prepared, as
hereafter described, are admirably adapted for paints and distemper colors for
general and artists' use. The paints produced by my Invention are of different
colors, according to the kind of sand or sandstone employed, and they may be mixed
together or with other substances or coloring matters to produce different colors or
shades, but they possess excellent drying qualities, and some of them have good body
and cover well without the admixture of any chemical coloring matter. Many are
transparent colors, and may be used for staining and glazing purposes.
According to my Invention the sand or sandstone above mentioned is first burnt
or calcined in an open or close vessel, and then ground to an impalpable powder by
any suitable means, and then mixed with oil, spirits of turpentine, size, water, or
other suitable vehicle.
When desirable to increase the body, and render the color brighter, iron pyrites
or sulphate of iron or sulphur in suitable proportion may be mixed with the sand or
sandstone during the calcining process, and burnt therewith.

page_text: If the material whilst hot be thrown into pure water, or water in which a certain
proportion of saltpetre, soda, antimony, potash, bluestone, alum, or other chemical
matter has been dissolved, or into tar, different shades of color will be produced.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Knight in the Great Seal Patent Office on the 5th July
1878.
HENRY KNIGHT, of Ryde, in the County of Southampton. "THE MANUFACTURE
OF PAINTS AND COLORING MATTERS OR PIGMENTS FROM COLOURED OR FERRU-
GINOUS SANDS AND COLOURED SANDSTONES, AND IN THE APPARATUS EMPLOYED
THEREIN."
My Invention consists in the manufacture of paints and coloring matters or
pigments from the coloured or ferruginous sands and coloured sandstones found in
the Isle of Wight and in other places in the United Kingdom, and manufactured,
as herein-after described, that is to say, either with or without the aid of chemicals
or other matter.
When I burn or calcine either sand or sandstone I use retorts provided each with
a cover and ascension pipe fixed and heated in the same manner as the retorts used
at gasworks for the making of gas, and I make use of the ascension pipe to relieve
the retort of any excessive pressure there may be during the burning or calcining
of the materials before or herein-after to be described. I charge the retorts to
about one-sixth of their capacity, and then subject the material therein to a red
heat, the doors of the retort remaining open during the burning to obtain a bright
colour, but I close them during the burning if I require the colour dark. The time
I burn the material greatly depends on the nature of the sand or sandstone, the
time ranging from half an hour to six hours. When ready to be drawn I place an
iron barrow below the mouth of the retort, from which I draw the charge into the
barrow by means of a suitable iron hoe, and afterwards I tip the sand into a
suitable place to cool; but if I wish to make the material of a darker shade I pour
the hot material from the barrow into a vessel containing water, or an aqueous
solution containing saltpetre, soda, potash, sulphate of copper, or other chemicals.
When I desire to brighten the colour I mix with the sand or sandstone during
the calcining process a suitable proportion of iron pyrites or sulphate of iron or
sulphur, which I burn together with the sand or sandstone.
Sometimes before burning I mix coal tar with the sand or sandstone in sufficient
quantity to bind the material together, and I then heat the same in a closed retort
until the flame from the tar has ceased. This produces a good black, but if I burn
the same combined materials with the mouth off the retort the material will be of
a dark colour when the flame from the tar has ceased, and if I still further calcine
the material, leaving off the mouth-piece of the retort, I can produce brown colours
of various shades, according to the time of burning, which varies from half an hour

page_text: to an hour, during which time I occasionally stir it to cause the material to be more
equally calcined. By using Stockholm tar in the place of coal tar a good brown is
obtained.
In burning small quantities of either material I prefer placing it upon metal
plates or trays, which, being more equally heated, gives the best colours. These
metal plates or trays may be used in the retorts and on an open fire.
The sandstone being in solid lumps I sometimes calcine it in a lime kiln, using the
same material, and burning it in the same manner as chalk is burnt for lime, but I
use only about one-fourth the amount of fuel that is used with chalk, and a slow
draught. The time of burning depends on the draught allowed, as the sandstone
should remain long enough to burn out the fuel mixed with it.
I make a chrome yellow with an aqueous solution of bichromate of potash, in
which I boil the sand or sandstone over a slow fire until the moisture is evaporated.
The proportions to make a good deep chrome would be 112 lbs. of bichromate of
potash in 35 gallons of water, and. when dissolved add seventy pounds of sand or
sandstone previously ground to a fine powder. I prefer boiling it in a copper with
frequent stirring. The depth of the colour will vary according to the strength of
the bichromate solution, and the colour of the sand or sandstone boiled in it.
I grind the sand or sandstone, or my combinations therewith, in the way and by
means of the mills herein-after described and illustrated.
I sometimes use the mills to grind the material before burning as well as after
burning. Prior to starting a mill I run water into it, and after the mill has been
set in motion I commence shovelling in the material gradually, allowing an equal
quantity of water to run in with it. Into a large mill I put about half a ton of
material. As the material gradually thickens during the grinding I constantly add
more water to thin it, which causes that which is least ground, being heavier, to
sink and pass beneath the mullars.
When I consider the material ground sufficiently fine I run it off at the plug-
hole into a large vat, which is provided with several plug-holes, each a few inches
above the other. With any suitable tool I now stir up this ground material, and
after allowing it to stand and settle a few minutes, that any coarse particles may
fall to the bottom of the vat, I draw off the material that will run from the top plug-
hole, causing it to pass through a fine silk sieve into a tub, returning to the mill for
further grinding the material which is retained in the sieve. I again stir up the
material in the vat, and after leaving it to settle as before, I draw it off at the second
plug hole in the manner above described, and I repeat this process at each conse-
cutive plug-hole till the material has entirely run out of the vat. That which has
passed through the sieve I allow to stand in the tub for a few hours to settle when
I draw off all the clear top water, and then by means of heat I evaporate all the
remaining moisture; then the material has only to be broken up and passed through
a sieve, when the paint colouring matter or pigment is manufactured.
For use it may be mixed with oil, spirits, turpentine, size, water, or other suitablo
vehicle, and is admirably adapted for paints and distemper colours for general and
artists' use. They may be mixed together or with other substances or colouring
matters to produce different colours or shades, but they possess excellent drying
qualities, and some of them have good body, and cover well without the admixture
of any chemical colouring matter. Many are transparent colours, and may be used
for staining and glazing purposes.
Having explained the nature of my Invention, and the mode of manufacturing
the same, I will proceed to describe with reference to the accompanying Drawings
the mills I prefer to use for grinding such sand or sandstone into a pulp or very
fine powder for paints and colouring matters or pigments, according to my
Invention.
Figures 1 and 2 represent the front elevation of two grinding mills driven from
one horizontal shaft A by bevil wheels which turn the two upright spindles B
attached to the mullars C; the pulley of the shaft having a rotary motion gives a

page_text: circular turn to the spindles attached to the mullars, causing the mullars to revolve
on the bedstone D in the tub E.
Figures 3 and 4 are plans of the mullars and bedstone used in Figures 1 and 2,
lettered respectively C and D, as in Figures 1 and 2.
Figure is the front elevation of a grinding mill. C represents the mullars; D,
the bedstone; E, the tub in which the mullars revolve.
Figure 6 is a plan of the mullars and bedstone of Figure 5, lettered respectively
C and D, as in Figure 5.
Figure 7 is a front elevation of a grinding mill. C represents the mullars; D,
the bedstone; E, the tub in which the mullars revolve.
Figure 8 is a plan of the mullars and bedstone used in mill, Figure 7, lettered
respectively C and D, as in Figure 7.
Figure 9 is a plan of a large mill, showing four curved iron arms F radiating
from the centre for driving the mullars C with a circular motion over the bedstone
D in the tub E; the mill may be driven with the bevil gearing of Figure 1, either
from above or beneath the tub.
Figure 10 is the same kind of mill as Figure 9, only having straight iron arms
instead of curved ones.
Figure 11. C is a circular stone or mullar; D is the bedstone.
Figure 12 represents plan of bedstone in Figure 11.
Figure 13 is a mullar showing a bevilled edge at the base to admit the sand or
sandstone under the mullar.
Having now described the nature of my said Invention, and the manner in which
the same is to be performed, I wish it to be understood that I do not limit myself
either to the precise details herein described, or to the mills illustrated in the
Drawings, as the same may be varied without departing from the nature of my
Invention, but I claim as my Invention in the manufacture of paints and colouring
matters or pigments from the coloured or ferruginous sands and coloured sandstones
found in the Isle of Wight and in other places in the United Kingdom,―
Firstly. Treating such sands or sandstones substantially in manner and by the
processes herein-before described.
Secondly. A combination of such sands or sandstones with coal tar, iron pyrites,
sulphate of iron, or bichromate of potash, substantially in manner and by the processes
herein-before described.
Thirdly. The application of mills herein-before described and represented in the
accompanying Drawings for the purpose of grinding such sands or sandstones."
Fourthly. The application of retorts and kilns for the purpose of burning or
calcining such sands or sandstones.
In witness whereof, I, the said Henry Knight, have hereunto set my hand
and seal, this Fourth day of July, in the year of our Lord One thousand
eight hundred and seventy-eight.
Witness,
JOHN MORRANT,
Union Street,
Ryde,
I. of Wight.
HENRY KNIGHT. (L.S.)