Gauthier-Villars.
_Experiments of Captain Bing on the Sensitiveness of Coal Oil_.--The
same Captain of Engineers has undertaken a series of very interesting
experiments on the sensitiveness to light of one or two substances to
which bitumen probably owes its sensitiveness, but which, contrary to
what takes place with bitumen, are capable of rendering very beautiful
half tones, both on polished zinc and on albumenized paper. These
sensitive substances are extracted by dissolving marine glue or coal-tar
in benzine. By exposure to light, both marine-glue and coal-tar turn of
a sepia color, and, in a printing-frame, they render a visible image,
which is not the case with bitumen; their solvents are in the order of
their energy; chloroform, ether, benzine, turpentine, petroleum spirit,
and alcohol. Of these solvents, benzine is the best adapted for reducing
the substances to a fluid state, so as to enable them to flow over the
zinc. The images obtained, which are permanent, and which are very much
like those of the Daguerreotype, are fixed by means of the turpentine
and petroleum spirit. They are washed with water, and then carefully
dried. It is possible to obtain prints with half-tones in fatty ink by
means of plates of zinc coated with marine-glue. Some attempts in this
direction were shown to me, which promised very well in this respect. We
are, therefore, in the right road, not only for economically producing
permanent prints on paper, but also for making zinc plates in which the
phototype film of bichromatized gelatine is replaced by a solution of
marine-glue and benzine.
Pages:
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60