The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1866-05-16
NOTES ON SCIENCE.
PHOTo-LITHnGRApHY.


Mr.. j. V. Osborne has invented a method by
which photograph in lithographic Ink adapted
Tor transierence to stone by the usual lithogra-
phlc operation ready for printing in the ordi-
nary way, can be executed in the course of q
few hours. The process is not adapted to por-
traits or views taken from nature, but it is IN
tended to reproduce, by the chemical agency of
light, perfect facsimile of maps, plans, pen
and-ink drawings, printed documents and en-
cravings. 1t is confined to black and white
drawing, and cannot render half tones, shading,
indla-ink drawings or paintings. Its range
for aoaFy As as is eed
in taking a very tine and sharp negative of
any given map or drawing. The positive from
this is printed in the usual way, upon paper
sensitiZed with bichromate of potash, gelatine
and albumen. The bicbromate, in the presence
OF organic matter, undergoes physical change
in the light and is easily adapted to receiving
the transfer ink. The sun does the copying and
thus secures perfect reproduction of the ori-
ginal. 1t makes no difference to the pencil of
light whether 1t has to copy a simple or COM
plcated drawing-both are finished in the same
time; but the photographer would require week
longer for one picture than for another. By Mr.,
OsDorne's process piece of work sent into the
Office in the morning can be Autographed and
printed in the afternoon. If the inventor can
produce all that is claimed for the process-and
there seems to be no good reason for doubling
the evidence on the subect-it will be a valua.
BILE contribution to the publisher of illustrated
DOCKS and TO the Typographical bureau of the
Government. 1t ought to be thoroughly tried.
A graphotype process has also been recently
introduced. 1t is entirely different from the
above Very fine and pure French chalk is
snted upon zinc plate and subjected to tue
great force OF hydraulic press. The artificial
stone is then properly prepared, and the picture
drawn upon vt with peculiar pencils, and the
sunken portions removed by brushes. The
chalk is then hardened by being soaked in LIQUID
quartz, and copy taken with type-metal, ac-
cording to the usual stereotype process The
metallic copy can be furnished three hours after
the completion of the drawing upon the chalk
1t IS claimed for this method that the expense
OF hthograph1c stones is avoided, and that
durable stereotype is obtained; whereas, in
lithography, the drawing must be removed
before a new picture can be begun. combina.
tioD of photography with this method would
seem to offer great advantages in the reproduc-
tion of all black and white work.
AN AUToGRAPHIC TELEGRAPHIo APPARATUS.
The apparatus invented by Caselli produces
autoeraphically telegraphic dispatches IL is
now IN operation between Paris and LYONS and
will be extended to Marseilles. Tue same appa.
ratus can be used for repeating designs
RECOVERY OF PURE SILVER FROM PHoToGRApH
REsIDUEs.
DR.. Van Monckhoven has published a method
hrst proposed by NJ. Stas;-
l. From old baths-Filter, add ammonia until
the precipitate is rsdissolyed, and then saturate
with sulpAurous acid gas or add sulpbite of
ammonia. Heat the liquor TO about i04 deg,
Fahrenheit ior about an hour, when all the sil.
yer will be precipitated. This silver, after
thorough washing, will be pure enough to be
dissolved in nitric acid in the preparation OF
nitrate. a.".
2. From washpg-The washing may be col.
lected In barrelin which sheet of copper is
placed. The sive. will be precinitated in sbont
tWenty-ionr hours This can be dissolved in
nitric acid and treaed with ammonia and sui.
phite OF ammonia G sulphuTous acid gas, as
above. w 80
8. From paper-Bua the papers one nv one.
30 as to get white as. Weigh the ashes. and
treat them with an eqnl weight of nitric acid
diluted with twice It's plume of water. All Of
sipitated by sheet copper and recovered r. AS
above. 10