IMPROVEMENTS IN WRITING INK
Year: 1885

page_text: I, LAURENCE HILL ARMOUR of 16, West Street, Gateshead, in the County of
Durham, Civil Engineer, do hereby declare the nature of my invention for
IMPROVEMENTS IN WRITING INK to be as follows:-
The object of my invention is to provide an ink which can be washed off paper
or fixed at will.
The first being for the purpose of being used by children in schools, and the
latter kind for use in the preparation of addresses, or documents in the copy of
which alterations may be required. I employ a mixture of such matter as drop
black with or without ultramarine, prussian blue, or other insoluble pigments and
water and gum or mucilage or similar colourless or nearly colourless medium with
by preference a little ox-gall to give fluency to the ink and if the ink is to be fixed
I employ a little gelatine, and chrome alum in the mixture, and write with it in
non-actinic light so as that on exposure to actinic light it becomes fixed by the
gelatine being rendered insoluble. Ink of the first kind will not stain children's
clothes, and by its use copy books may be used over and over again. It is mauifest
that many materials are available for the purpose so long as there is no solvent
dye and mordant in the ink, but these I have mentioned are what I prefer to use.
I call my invention School Room Ink, its peculiarity being that it can be written
with so as to give a good appearance, and yet that it can be washed off paper
without stain or disfigurement.
Dated this 13th day of January 1985.
J. HENRY JOHNSON,
Agent for the said Laurence Hill Armour.

page_text: I, LAWRENCE HILL ARMOUR of 16 West Street Gateshead, in the County of
Durham, Civil Engineer do hereby declare the nature of my invention for
IMPROVEMENTS IN WRITING INK, and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
The object of my invention is to provide an ink which can be washed off paper
or fixed at will. The first being for the purpose of being used by children in
Schools, and the latter kind for use in the preparation of addresses or documents
or drawings in which alterations may be required. I employ a mixture of such
matter as drop black or very finely ground charcoal with or without ultramarine
prussian blue or other insoluble pigments and water and gum or mucilage alone or
mixed with a little sugar, treacle, or similar matter, or I may use any similar
colorless or nearly colorless soluble medium, and if the ink is to be fixed I employ.
a little gelatine, and chrome alum or Bichromate of Potash in the mixture, and
write or draw with it in non-actinic light so that while it may be washed off before
exposure to actinic light it may become fixed after adequate exposure by the
gelatine being rendered insoluble.-Ink of the first kind will not stain childrens
clothes and by its use copy books may be used over and over again. It is manifest
that many materials are available for the purpose so long as there is no solvent
dye, and mordant in the ink, but those I have mentioned are what I prefer to use.―
I call my invention School Room Ink, its peculiarity being that it can be written
with, so as to give a good appearance, and, yet that it can be washed off paper
without leaving any stain or disfigurement.
I may use this ink on any ordinary paper or parchment, or, as for instance for
childrens school books, I may use it in combination with a specially prepared paper
of extra, hardness, or possessing such surface as to be less liable to injury by
washing or repeated washing than ordinary paper; or with vegetable parchment.
⚫ Having thus described the nature of my invention I will proceed more particularly
to describe the manner in which the same is to be performed, that is to say :-
In order to ascertain if any material is suitable for the coloring matter of the
ink to be made, that is to say whether the ink made from it can be washed off
paper so as to leave no stain I mix a considerable quantity of the coloring matter
with a small quantity of water and then filter part of the water from it, or allow
it to settle; if the water filtered from it or obtained by its subsidence be quite
clear and free from color, the material is good for the purpose, but if the water
be stained or colored to any considerable extent, the ink made will be apt to leave
more or less stain on paper after washing.
For the manufacture of soluble ink I prefer to make a mixture of gum arabic
and water and to mix and grind with it vegetable charcoal and then to run it into
a settling tank where I allow it to rest for some time. It usually happens that a
part of the charcoal rises to the top and makes a too thick ink, and a part settles
to the bottom and makes a too thick ink, and I therefore reject both the top and
bottom of the contents of the tank and draw off the intermediate portion returning
the top and bottom to the mill for further grinding. I find that the density of a

page_text: solution of gum such as flows freely in writing when mixed with charcoal, is
adequate to retain in suspense for a considerable length of time a sufficiently dense
coloring of charcoal to make a good ink.-But I prefer to add to the ink common
salt or chloride of ammonium both as a preservative against decomposition and to
increase the density.-With certain other coloring matters however possessing
greater specific gravity it may be necessary to increase the density of the solution
of Gum, in order to retain the coloring matter more effectually in suspension, and
to accomplish this without at the same time making the ink too thick, I use
common salt or any soluble salt increasing the density of the solution without
injury to the purpose for which the ink is to be used.
The addition of purified ox gall gives especially if pen or paper be at all greasy,
greater fluidity to the ink and may be used or not as desired.
For various colored ink any convenient light insoluble coloring matter may be
used exactly as the black color is used. If it be desired to make the ink removable
or fixed at will I employ as a medium for the suspension of the coloring matter a
weak solution of gelatine with Bi-chromate of Potash or chrome alum such as is
used for carbon photographs and I write with the ink in non-actinic light and then
expose it for fixing to actinic light.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I. declare that
what I claim is
1st The production of writing ink of such character as that it can after use be
readily washed off paper or parchment so as to make the paper available for use
again substantially as described.
2nd The production of writing ink of such character as that it can after use if
not exposed to actinic light be readily washed off paper or parchment, but which on
exposure to actinic light becomes fixed-substantially as described.
J. HENRY JOHNSON,
Agent.