A very rapid process to make newspaper illustrations, called
gelatinography, is described in the following:
A black glass plate or a tin plate coated with black varnish, as used by
sign-painters, is covered with plaster of Paris (gypsum) to a thickness
of four-ply cardboard. The plaster of Paris must be of the best quality
and reduced to a very fine powder. Add thereto some alum and some
sulphate of barium, and in order to prevent the coating from being too
brittle, add also a trifle of glycerine or of a gelatine solution.
This mixture must have the consistency of a thin pulp when applied to
the glass or tin with a soft camel’s-hair brush.
When dry, the artist may engrave into this coat of plaster of Paris, by
means of a lithographic engraving needle, any design or picture with the
greatest ease; the plate or glass is thereby laid bare, and design or
picture appears black through the plaster of Paris coating. Mistakes or
errors are easily remedied by filling in the plaster of Paris
preparation.
With the regular printers’ roller composition a stereotype is now made
of the picture or design on the glass or plate, in the usual way; some
bichromate of ammonia solution should be added to the roller
composition, to make the stereotype hard enough for the type press, and
it will be as durable as any electrotype, and answer the same
purpose.--_Am. Lith. and Printer._
* * * * *
STEREOSCOPIC PHOTOGRAPHY.--Of late, there is quite a revival in this
branch of our art-science, several English and many foreign amateurs
having been working with twin lenses during the last and present
seasons. The Belgian _Bulletin_ has an article on the subject, and the
last technical meeting of the Photographic Society was devoted to it.
Although Wheatstone announced the instrument in 1838, it was not until
photography had come to his aid by furnishing satisfactory diagrams, and
Brewster had popularized the matter by the invention of the lenticular
stereoscope, that much progress was made; then Wheatstone gave his
Bakerian lecture on January 15th, 1852, to put the finishing touch to
this important branch of scientific work. The earlier attempts failed by
reason of employing too wide an angle.