Telegram-herald., 1889-07-23
AN ARTISTIC EVOLUTION.
The Sunbeam Hzrnessed 20 the
Printing Prsss.
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iEl1e~s produced ~ j. ecald hot be multi
Piled ezcefs D repstlEi'sa. ~ many tines
as ocples were desired. CT the ccstly and
tedious ORIGINAL process Ihe fact w2s
Clearly sDprehended cy scientific and
practical uea that 10 h1d but o1ened the
~ay - = fed II Infinite posi- icilities. Il
was uOt yet sh0uzh that tie sunbeam
should &c iEnprisoaet u The camera; Il
Iallst bs h1rnesse1 % The printing press
A cretitz1ls attenp. Ia that direction
~zs made ly Sir ". T. Grove. who, not
long after ths inventisn Il t. dagusr-
reotyge. discovered : means ~ etching
l. Ia tie plats. WITH aid. % . sufficient
depth % euAols-&isA very delicate ma
nipu-sEloa-pinting from l.. olt nis
process vr2s merely a. ingenious and ex-
penslse curiosity. a failure FOR al pr@c-
teal Parposes Tie steps were si0T BY
wAicn the present p.Ilec-loa oE tie at
w. reached
Aungo Patton. in 1880. discovered the
seasitIvsnes- of bi-chroEl-ls OF potash 10
light IN ie4l, iox-Ialbsl. cf England,
did the first real Photography 0y what
he denominAte1 tie ''ca.otype' process.
bus IN what would now seem very
crude way Hs saade his negatives upon
paper. which was subsequently, waxed
and rubbed with ! hot i-on 70 render i.
semi Transparent Then he made his
posinves upon paper over which had
been noated album~n charged with
i0dide OF silver. That process, or a very
close approximation 70 it, by the way. Is
still in use in Paris for the making Of
magic lantern ''siidee," an at in which
We now excel
Louis Alphonse Pointevin in 1850
made the great improvement Of employ
ing for negatives plates Of glass coated
with 'gelstine or other orvanic matter
in combination with the ii-chroma,e Of
potash or of ammonia" From this point
really have sprung al tho many ingeE-
ious. and FOR thoi- respective usrs
enormously valuable. processes OF pro-
ducing photo-rehef, photo-lithograpAic
and other plates for various sorts q
printing. Volumes would be required
10 recapitulato tho improvements and
variations that have been made since
Pointevin's time-in all civilized coun-
tries. but principally n the United States
but al rest directly upon his invention
rs base, and Pointevin as the father OF
modern photography is hardly less
worthy OF honor in remembrance than
Dasucrre. It is true that in 1917 Niepce
de st. Victor used iOdized al6umen on
glass sens;tized with nitrate Of silver
with fairly good results; also that Scott
Archer, of England. IN 1851 brought col
lodion-which had then recently been
invented for surgical uses By lie Grey
into use, but neither Of them reached the
point OF practically attained by Pointe-
win with gelatine. u. Pierre Ignace
Alexis GGudin IN 1853 introduced col
lolion emulsion the formula OF which
did not get into general use, but served
as the basis for number OF improve
ments little later and was employed
/ for several years thereafter. In 1851 he
Inado gelatine emulsion and called il
'ph0sogene."
Not long after Pointevin's discovery
Paul Pretsch, OF Vienna, found that if
he coated 4 plate of glass with b;chro-
matted gelatine TO a thickness three or
four times rs great as that employed by
POintevin, and when it was dry exposed
it il contact with a Photographic live
negative, the gelatine where the light
acted upon Il was rendered insoluble and
hard. while from the other parts, where
the light had not acted. the bi-chrcmate
could readily De washed out, and the
gelatine there would absorb water and
swell up just in proportion as it had been
protected from the light, giving 2 per
feet natrix from which plaster casts OF
electrotypes could - made. So delicate
bus sure was the action q the light that
half tones were preserved and the repro
ductioa Of accurate printed copies OF the
original seemed 10 lie. theoretically az
least. merely ! matter Of color and i'm
preston. L. practice, however. il was
found tnat there was . great deal Of i'm
provemont stili necessary before the pro
cess could be made commercially vaiua.
Die. Cae Of tie moderately succcs8f ful
methods tried was that Ct coating metal
states wi.h asphaltin, which hardened
under the light and could be removed
readily b7 solvents FROM the urexpOsc-
parts, thIs presenting surface ioE ctch-
inE Lined and s.ipp,od work coald he
well reproduced In that way. ous tie
uzctu.aess Of tne process w2s i-mi-ed.
Fliatevin produced somo god work
7 hy coating bis glass plates th.aly with
. celatne ard printing fron them as from
+ ithorr 2hlc stones. tho paris expoed s.
T iirit taking ink. while tao1e rlt czroaol