Improvements in the Manufacture of Plumbago or Graphite commonly called Black Lead.
Year: 1894

page_text: Date of Application, 29th May, 1894-Accepted, 30th June, 1894
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Plumbago or Graphite
commonly called Black Lead.
I, PERCY FORREST JOHNSON of Grecian Chambers, 57 Dale Street, Liver-
pool, in the County of Lancaster, Manufacturer 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 :-
This invention has for its object improvements in the manufacture of stove or
grate polish commonly called black lead and other polishes of a like nature used
for household purposes and for lubricating and other purposes.
By my process all such plumbagos or graphites as have been recognised as
incompressible or impossible of being compressed into blocks or tablets of sufficient
solidity to be handled, are rendered easily compressible and are materially improved
in polishing power, a more brilliant effect being obtained, while the effect is much
more lasting than has been possible heretofore.
My invention also applies to plumbago or graphite used in the manufacture of
crucibles cr firing pots, and by its means the hardness and durability of these
articles are much improved, and their weight greatly reduced from what they are
when made of plumbago or graphite combined with ordinary fire clay. For use
in pencils, black lead made according to my invention has great advantages,
hardness being obtained without brittleness and blackness without undue softness.
Such being the object of my invention I further declare that in order to
accomplish this I combine with plumbago or graphite an impure silicate of magnesium
commonly known as steatite, talc, or soapstone, in any one of its various forms, and
alum, sulphate of alumina, or other aluminium compound.
The proportionate parts of the ingredients used in the manufacture of black
lead according to this invention will vary to meet the requirements of the various
plumbagos or graphites, some of which are more rich in carbon than others, while
others again are quite unsuitable for certain purposes, but the average formulæ will
be as follows
Alum
"
The various plumbagos or graphites selected for the admixture, or any of them,
having been ground to the necessary fineness and passed through a sieve of silk, or
bolt cloth, or other suitable material, of a mesh of say 120 to 150 are then weighed
and divided into the necessary proportions and treated in the manner as hereinafter
described.
A suitable receptacle charged with a saturated solution of alum, sulphate of
alumina, or other aluminium compound, is heated by a steam worm or other suitable
apparatus up to 212° Fahrenheit, to which is then added the most highly
When the
carboniferous plumbago or graphite to be employed in the admixture.
plumbago or graphite has become thoroughly saturated with the solution of the
said aluminium compound the steatite is added with a further addition of water if
found necessary, and the whole of the ingredients are thoroughly mixed, after
which the water is evaporated until the admixture is of such a dryness as to admit
of being placed in a chilled steel, or other suitable mill, or mixer, as may best suit
the requirements of thoroughly mixing and grinding the admixture, to which is
now added such other plumbago or graphite (if any) as may be found necessary

page_text: and suitable for the particular purpose for which the preparation is to be employed.
The ingredients must then be thoroughly ground and mixed together.
For household purposes the black lead is then compressed by any suitable
machinery into tablets, cakes, or blocks of convenient size.
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 :-
The combination of plumbago or graphite with an impure silicate of magnesium
commonly known as steatite, talc, or soapstone, and alum or sulphate of alumina
or like combinations.
J. E. EVANS-JACKSON & Co.,
Agents for the Applicant.
CUTE TO Concz su n
J. E. EVANS-JACKSON & Co.,
Agents for the Applicant.