A New or Improved Process for Obtaining Positive Black Line Copies from Positive Tracings or Negatives by the Action of Light.
Year: 1887

page_text: Date of Application, 8th Sept., 1887
Complete Left, 21st Apr., 1888
Complete Accepted, 1st June, 1888
A New or Improved Process for Obtaining Positive Black Line
Copies from Positive Tracings or Negatives by the Action of
Light.
I, GUSTAVE BAY, of 22 rue de la Chaussée d'Antin, Paris, France, Chemist, do
hereby declare the nature of this invention to be as follows:-
My new or improved process relates to obtaining positive black ink copies from
positive tracings or negatives, by the action of light, and is based as follows:
1. On the reduction, by the action of light, of the salts of iron in the presence of
organic acids (citric, tartaric, etc.).
2. On the formation of a brownish precipitate, produced by these salts in the
presence of the yellow or red prussiates of potash, combined with certain yellow, red,
and brown vegetable coloring matters and the extracts and lakes of such matters.
3. On the formation of a precipitate of coloring matter varying from red to dark
brown, produced by hydratic alkaline matters such for instance, as soda, potash,
ammonia, lime &c., and the salts derived from them in the presence of a decoction or
infusion of such coloring matters or of their extracts.
I dip the paper in a solution of gum arabic, tartaric acid, and perchloride of iron,
I leave it to dry, and afterwards I expose it in a photographic frame under an Indian
ink tracing or any other suitable negative; on taking it out of the frame, I develop
the copy upon a bath of water saturated with prussiate of potash, after which I place
it upon a bath consisting of a decoction or infusion of the coloring matter. When
the copy is quite black, I wash it under a water tap, after which I dip the sheet in a
bath consisting of a salt of soda, ammonia, potash &c. The degree of saturation is in
fact of little importance, provided the salt is neuter, and has an acid action with an
alkaline reaction. The acid clears the background, whilst the alkaline matter
destroys the blue produced by the salt of iron and the prussiate, and fixes the copy,
by means of the precipitate with the coloring matter, either in violet, brown, or
black, according to the salt used, and the duration of the bath.
I finally wash under a tap, with a brush and plenty of water. The baths may be
used until ineffective.

page_text: I can also obtain copies by a single bath, by mixing in about equal quantities, the
two baths of prussiate and coloring matter, the development of the copy being my
guide in the matter.
On taking the sheet out of the frame, I place it for 5 or 10 minutes upon this bath,
after which I wash it with a brush. The copy will then appear black upon a
yellowish background which I can subsequently clean and bleach by means of a bath
of alkaline salt.

page_text: organic acids (citric, tartaric etc.).
2. On the formation of a brownish precipitate, produced by these salts in the
presence of the yellow or red prussiates of potash, combined with certain yellow, red,
and brown vegetable coloring matters and the extracts and lakes of such matters.
3. On the formation of a precipitate of coloring matter varying from red to dark
brown, produced by hydratic alkaline matters, such for instance, as soda, potash,
ammonia, lime, &c., and the salts derived from them in the presence of a decoction
or infusion of such coloring matters or of their extracts.
I prepare a paper with a solution of gum arabic, tartaric acid, and perchloride of
iron, I leave it to dry, and afterwards I expose it in a photographic frame under an
Indian ink tracing or any other suitable negative; on taking it out of the frame I
develop the copy upon a bath of water saturated with prussiate of potash, after which
I place it upon a bath consisting of a decoction or infusion of coloring matter. When
the lines of the copy are quite black, I wash the copy under a water tap, after which
I dip the sheet in a bath consisting of a salt of soda, ammonia, potash, &c. The
degree of saturation is a matter of little importance provided the salt is neutral and
has an acid action with an alkaline reaction. The acid clears the ground whilst the
alkaline matter destroys the blue produced by the salt of iron and the prussiate, and
fixes the copy, by means of the precipitate with the coloring matter, either in violet,
brown, or black, according to the salt used, and the duration of the bath. I finally
wash under a tap, with brush and plenty of water. The baths may be used until
ineffective.
I can also obtain copies by a single bath, of about half of prussiate and half coloring
matter, the development of the copy being my guide in the matter.
On taking the sheet out of the frame, I place it for five or ten minutes upon this
bath, after which I wash it with a brush. The copy will then appear black upon a
yellowish ground which I can subsequently clean and bleach by means of a bath of
alkaline salt.

page_text: 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 :
The production of a direct positive black line copy on a white ground of previously
sensitized paper, such copy being obtained by means of an Indian ink tracing, by the
action of light, by 1stly the combination the yellow, red, and brown vegetable
coloring matters, with the precipitate formed by persalts (salts at the maximum of
strength) of iron, and prussiates of potash; and 2ndly the cleaning and bleaching of
the ground of the copy by a solution of neutral salts having an acid action, and at the
same time an alkaline reaction, substantially as described.
A. H. REED,
Agent.