, 1875-11-14
It's Principle, Application, and Results
Harvard College Collection.
ar. Healy's Portraits---Sale Of Vainl's
Pictures and Effects.

PHOTOGRAPHIC ENGRAVING.

sige OF works Of art. 10 former article, upo
Eoodburytypea, it was pointed ont that in i
The processes OF making Photographic picture
The method Of taking tho negative is tho satuf
and tho differences are in the mode OF printiu
from the negative. AL the processes Of photo
graphic engraving are dependant upon the gus
ty nf gelttinc, when treated with bichTonste O
potash. Of becoming On exposure TO light insol7
tie il water.
In the Woooburysype process and Couple
"rlotozrayure," bichromated gelatine alm
made into relief by exposure to Light unda
the negative and subsequent washing With water
is used for producing in soft metal By stamping
ucder pressure plasa which can be used Like
N Ordinary copperplate for printing impress
ssons with ink.
Two other processes are familiar By their prod
ucte to all art-students, very different from
those already described, and very different {tou
each other. One il the method employed in
BRAUS's PHOTOGRAPHS,
widely known for the reproduction Of the paint
ires IN the 6istine Chapel the drawings Of the
old masters in the Uffi1 Gallery, and other
standard and valuable works Of art This is not
smo3e Of photo-engraving, but is strictly de-
kcrihed By ITS name Of "csrbon photograph" "
carbon coloyiug matter which is exposed to the
light. aud afterwards partly washed away. and
then by ingenious processes transferred bodily
to the paIter. where it forms the final permaneot
printB which answer go admirable 8 purLose. In
.his case ne have actually in the single picture
the gclatine fl, which is used ia tbs other pro
cesscs 2s 3 plate or matrlx to print many
pictures from a separate print from the mega
tive is necessary for every impression and the
pictures are necessarily rather expensive.
Tne second process IL hu6 method OF photo
engraving. aud perhaps the most valuable now
LII use, known ~
THE HE1IoTTFE PROCESS
1h. ie becoming 50 Important an adjunct OF all
stpdies Of dne art that it merits somewhat par
ticu}ar description. Mr. Ernest Edwards deiiv-
cred ~ address before the Society OF Arts at tbs
Massachusetts Institute OF Technology in 1872,
In which the process WAS ex lalned In full. The
distinctive feature OF The heiotype process is
That The felatine film which IN Woodbury's,
Goupils'. and the pboto-ltthozraph methods. IL
used as an agent for transferring the piSture to
metal or stone, and in Branhs photographs is it.
self tsuneferte ed to the paper,-thss eela.lne film
ia itsaf used printing plate. aud all the i'm
lresslons come straight from & su.face which
has been EXPOSED under the negative directly to
the acton Of the light.
While tue action OF hot water On gelatine is to
dissolve it, the action Of cold water is not to
dissolve it but simply TO swell it up Like
sponge Tho action Of light ID to close up the
pores go that it Will pelther be dissolved by hot
water noe s~oneu ~ eo:o' enu tala nay taso
Place to greater or less extent According to
the degree of exposure II . Photographic
gea;sDe plate is stepped in cold water, the pats
o. It auecsed ~ nghs 50 that tne pores are
c!oaeu. Will iece'se water ana the TEL Will re-
1nse II ana II hthogfspnlc 1na. when IS OF
ETeasE qcahtst le Applied to tue plate, the ink
Will adhere IN the portions that CONTAIN no
water and fail to adhere in the rest so that the
picture VIII be revealed IN fient and shade.
FARTHER HTEP N TEE PROCESS
- necessary because q the peranaoie nature OF
1he pa11s OF tne ge1atne MN unan nectea bJ the
llght: by aoml1tufe WIN ainn eelatlne IL CON
Setbea 1nto A17ugn' ieAsae1.llke SUBSTANCE, *a1cn
yet lesalns tne q'tAuty OF oelnE acted rpoh b5
Aehr ana an IMPORTANT part o. the hehotype
process ,1s tne t1e21ment OF the ee!a1lne Win
siuH- 1he photographer Inen nas LID. tough
ttlm to deal WITH lhlck enough to receive suf
ucient water 10 fe2et greasy lnk- out DOT too
thlcK 70 pr1nt from with faellt5. !hls him
II the original experiment WAS attached to
s'ass paate' ou. Qlincuttv was eneoun-
.eFeu n exposing u anaer tne mega
se On % nfGohna 9, .ne 8,l,ss VI sne Two glass
: entlal 10 cleat prints ana means we're devised,
~ thtetPos1ns "a1 oes"eeh tne EAm aoo me
l!ase 70 "nica II *as attaceeo LOT aotAentn8 tne
t4lul altoge.hel; ano lea9lne II nke piece OF
t5o"n ~ paper. 1oin- ue11p'e, ano .ouen. Misa
ln7, peI1ect eontaet WIN tne neeause anq tne
uer 10 pilnt l1on tue gethttae' A 1s necessary 70
suPport II upon ENC OF copper pate. shen 1t Is
Eeeo II Efess 1he any eseel or copper pate. out
can De oetacneo at any sme, ano packed Away
ID 'ts tnln paPely conaIion. -.....
A1ultnel nelunp1o'euent IN tbe process as actual
e used Is IN The inkinE. TWO or more inks beng
used IN succession. OF dincrent lnteue1tiea and
colors' II deslred, from Which hne effects are
Proanced.
From elnEle golatfne plate as many a. ], 500 !
'mpTesslons are sometlmea uEen, or " pulled"
10 Use fhe engraFe1s word. without dtterloT1- |
HON bn. as the geiasape hims are more delicate
Than meeal!1c plates, they Aie liable to accidents
ander careless usage. fresh plate, however. |
may 10 rFeEarcu IN m hour at a lew cents ex- |
pcnse, 50 that tho reduptcatlon may be carried |
e any extent. one man WILL print from 100 to
1ou Impressions Gay.
sCcH 1s THE PROCESS. WHAT OF THE RESULTS?
The resu'Fa are OF al sorts; th&t is to say, tbs
acil"type .process Turntables means OF making
:sproductIons of a'most all sorts OF pictures.
" hateTer c6n be taken b; photography can be |
oat into permanent form aud multiplied
. any extent At moderate cost By !
ne Ael!otype method. Objects ta-
zen from nature. persons, yiews, interiors
II buildings aEc.-resemble ordinary photo
;raphs, but possess the advantages OF durability
ND easy production in great numbers Much |
he same is true ct drawings Of various kinds,
, crayon. ren-and-iuk. pencil, OF Indian ink.
FOR line drawings such ~ engineers plans and