The Sun.
London, England, 1868-03-05 00:00:00

OCTOBER.

Broniley l. I Ealiug l5

DECEMBER.
1, Ealing 26
... 8i

St. Albans..
Kingsbury

PIIOTOGRAPHY.

The carbon process has arrived at such perfection
of late that it bids fair to beat the old silver one out
of the field. The principle on which it rests is
simply this: that gelatine mixed with bichromate
of potash or ammonia has the property of be-
coming insoluble under the action of solar light.
If, therefore, a negative be placed on a piece
of paper coated with bichromated gelatine, the
coating will be washed away in warm water
wherever light has not penetrated, and as this will
occur in the darks of the negative corresponding
lights will be obtained in the light. But as bichro-
mate alone would give but a pale yellow, a pigment
is added to the gelatine, Indian ink being most com-
monly used for that purpose. Now Indian ink is but
a preparation of carbon, and hence the name given
to the process. The paper coated with this blackened
gelatine, after receiving the impression of light
through a negative, loses all its black coating in
all those parts where the gelatine has remained
soluble, and it is thus a delicately-toned
print is obtained. The paper may be prepared
beforehand with blackened uubichromated gela-
tine, and kept indefinitely in this state till
required; it may be sensitized just before using
it by dipping it for a minute into a solution
of I.7sgins. of bichroinate of ammonia in
100gms. of water. The paper, when dry, is put
into a common printing-frame with the nega-
tive to be reproduced, but so that the latter
may be in contact with the back of the paper,
not its sensitised side. The impression,
being thus effected through the paper, will, on
developing, come out with the finest details. There
is one difficulty connected with this process; it is
the time of exposure. As the developing process
simply consists in washing away the soluble parts
of the coating, not the slightest vestige of a figure
is perceptible on the paper before that operation, so
that the time of exposure requisite has hitherto been
mere guess-work. M. Leon Nidal, in a paper
re-
cently published by him, points out an excellent
practical way of overcoming this obstacle. 'laving
remarked that the time is about the same required
in common silver printing, he exposes a strip of
sensitized albumenised paper simultaneously with
the carbon paper, covering the strip with a piece
of the latter uncoated. In this way he has only to
watch the progress of the printing on the strip, in
order to judge of what is going on in the carbon
frame. lie also makes a scale of shades from the
darkest black to the purest white ; and this scale,
when photographed, becomes a seat of photometer
with which to compare the intensity of the shades
of the carbon print.

SHIPPING INTELLIGENCE—This Day

GRAVESEND, Thursday Morning.

Arrived, Feb. 4.—Fttret, from Gravelines; Ealing Grove,
rom Demerara; Cleveland, from Foo-Chow ; Merry Heart,
from SL Michael's; Welsh Girl, from Tobago; Avdna4ee,
from Uddowalla.

Arrived, Feb. s.—Zjdiac, from Shanghai; Sarah Grico,
from Melbourne.
Sailed, Fe.b. y Queen, steamer, for Diepre ;
Blonde, S. It Peel, and Flancire, steamer—all for Duo-
kirk.

Sailed, Fob. s.—Zmlandia, for Moreton Bay.
DEAL, Thursday MorniniT

Anchored—Flora, from Singapore, for London ; James
Armstrong, for Demerara ; Ferrol, screw steamer, for
Ferrol : Witch of the Seas, for Algoa Bay ; Clementine,
for Brest; Earl of Mar and Rollie, for Barbadoes ; Saint
Joseph, for Bordeaux—all from London; Cornwallis, from
Calcutta, for London ; Anna and Olga, from Hull, for
Cette ; Borgund, from Ramsgate, for Lisbon.
Put back—St. Pierre and Jean Baptist, for the west.

Viscountess Amberley and infant daughter are
both progressing favourably at Lord and Lady Stanley of
Alderley'e residence in Dover-street.