, 1867-11-15
From HE London Times. September 30,1
THE GREAT FRENCH
EXHIBITION.
(Continued from No. 9l.)

And now we come TO what is called the
carbon process, or carbon printing. Is it
possible 10 print a photograph on paper
so that it shall be as permanent as the
impression of q steel engraving in prin-
ter's ink7 Whatever we may come to
hereafter, ii is generally accepted at pre-
sent that if a Photographic print is TO
rival ordinary prints in permanence, this
can only be by reproducing it in an ink
which, like printers ink, has carbon for
its base. So there are q great number of
ingenious processes for transferring to
gradations of carbon The gradations of
fight and shade which we sec in photo
praphs. The essential theory Of these
processes is suggested by the expert
ments ofM. Niepcc announced in 1927, and
of Mr.. Mungo Ponten announced in 1889.
There are substances, soluble in water,
which become insoluble when subjected
10 the agency of light. IF q Photographic
image be transferred TO the surface of
such o substance, the light passing
through the light parts Of the negative
and not through the dark will so act upon
the surface that parts of it will wash
away, and parts not. The surface when
washed will be raised or depressed ac-
cnrding to the quantity of light which at
different points has acted upon it and
the depressions thus contrlved will accept
a film of carbon, which in its various gra-
datioas OF thickness will more or less
accurately represent the lights and shad-
ows Of the photograph. The French
have had great success in the production
Of their carbon prints, NJ. GARNER and M.
- u -. M o,... b,:,, Vor,al vunrfhu
of gold medals. Most OF the French car
hon prints arc described as produced by
The process of Poitevin, who in 1856 sue.
ceeded in turning to account the dlscov-
ery of Mr.. Mungo Ponten. He combined
carbon or any other pigment in a fine
state of division with gelating, starch, or
gum. appiied il over the surface of his pa
Der, dried il, submitted it TO the action of
light under a Photographic negative, and
so first produced what is now usually
called a carbon print. Many specimens
are exhibited Of this form of picture;
some are of great beauty, and all pretend
10 the permanence which belongs to or
binary engraving. The chief English ex-
hibitors Of carbon printing are Mr..
Woodbury., Of London, MIR. Swan, of
NGWCdSttts dtti u O0uNC} VA
fer. Among these, as a discoverer, Mr..
Pouncey stands first in point of time.
His first announcements belong TO the
year 1s55-that is, three years after
Poitevin's first success. He is evidently
on the right path, and he deserves some
credit as one Of the earliest toiundcrstand
the Importance of carbon printing. But
q comparison of his results with those of
other exhibitors in the same line is not
satisfactory. His prints are rather coarse
III appearance +; in the production of them
a solvent is used which is expensive
enough 10 interfere seriously with the
commercial value of the process, and the
specimens which are exhibited in Paris
seem to be vanished 10 secure protection.
M. Swan, Of Newcastle, comes after Mr..
Ponncey in pointof time-his discovery
dates from 1864 but he appears to have
carried his process 0 carbon Pulling to q