The Republican. [volume] (Oakland, Md.) 1877-current, 1886-09-11
PHOTO-PRINTING.


PhotOgravure for Book Illustrations and
Zinco-Types for Newspaper Work.
The use of Photographic negative
in connection with photographic sur
face has become of such importance
| for almost every sort of illustrated
work, from the business circular to the
finest books of art, that the name OF
Poitevin, the French inventor and real
father of the process, deserves to be
better known than it is. Louis AL
| phonse Poitevin was born at Contains,
in tho Department of the Santhe,
| France, in 1919. His bent to wards ap-
piled chemistry led him early to the
Ecole Centrale, in Paris, where he de-
zeal and mechanical studies, leaving
the school in 1843 with the diploma Of
civil engineer. His first appointment
,, was that of chemist in the national
salt works in the east of France, in
which capacity he introduced many
improvements in the processes and
machinery used, and also in the manu-
facture of potash, sulphuric acid, etc.
When photography came upon the
world as a scientific curiosity, Poitevin's
taste for chemistry led him to expert
ment with the new toy, and in 1S4S he
| published the fact that it was possible
| to produce an electro deposit of cop
per upon the whites of the daguerreo-
| type image. His work in this direction
| led to the discovery of method of pho
| to-chemical engraving upon metallic
plates coated with gold or silver, for
which he received the medal of the
Societe Encouragement DIES Arts.
Soon afterwards he began work upon
the study of the action of light upon
| bichromated gelatine, He tirstapplied
himself to the production of molds in
relief, and patented in 1855 his hello
plastic process. which consisted in pre-
pairing a film of gelatine, which, after
sensitizing by means of bichromate of
potassium, was exposed to light under
anegative. When cold water was APP
piled, the parts Enacted upon by
light swelled up and so formed an
image in relief from which mold in
plaster or other suitable material could
be taken.
His next achievement was the ink
process. He discovered that the sur
face of the bichromated gelatine film
after exposure to light became re-
pellent of water, while it permitted a
greasy ink to adhere. In 1856 he
established workshop for the pro-
duction of pictures by this process.
Some of his early plates are in tho
possession of Mr.. Edward Bierstadt, of
this city, and compare favorably with
much work of to-day. Poitevin was,
however, too much engrossed in in
vention to prosper in business, and he
sold out the shop to Lemercier, who
still carries it on. and turned his at
tention again to experiments. In 1862
he perfected a system of carbon print
ing, from which the present processes
are derived. He also published re-
searches in connection with the action
of light upon various salts of iron. The
Due de Luynes awarded him the prize
offered for advances in applied science,
and at the exhibition of 1878 he was
adjudged gold medal and an honor,
arium of seven thousand francs in
recognition of his services. He died at
Contains, March 4. 1882.
Some of the best work done in this
country with processes growing out Of
Poitevin's invention is that known
under the general head of photo
gravure, which is printed directly from
an etched plate. The plate is covered
with sensitive film and afterwards
etched, the acid acting where the light
coming through negative has fallen.
From such a plate, using copper-plate
press, the New York company which
makes specially of this work pro-
duces very beautiful results. For fine
books, where cheapness is not sought,
the photogravure answers the purpose
admirably, for any number of impress
sions can be taken. The same company
also uses the gclatine plate process, as
modified by Mr.. c. T. Roche. Some of
the large plates and reproductions of
sepia sketches, done in this way, are
admirable specimens of the art at its
best.
For purposes of newspaper illustra-
ton, especially in colors, zincography
is much used in Europe and, to small
extent, in this country. Zinc plates are
coated with an asphaltum film and ex-
posed under negative or drawing from
ten to sixty minutes. Asphaltum in
certain conditions is sensitive to light
Where light acts acid can penetrate to
the plate, and it is etched in the usual
manner. When it is desired to print
in colors, a negative is prepared for
each color, one allowing no light to
pass except for yellows, another reds,
etc. Many German and French news
papers are illustrated by this process.
The colored plates in the last Christmas
number of the Paris Figaro, so largely
sold in this country, were photo-zinco-
types.-N Y. Post.