other substances having polished surfaces, e. g., earthenware, copper,
etc. The original drawings or images should be well executed, and drawn
on white, or preferably bluish paper, similar to paper used for ordinary
drawings. In the patterns for glass painting, by this process, the place
to be occupied is marked by the lead, before cutting the glass to suit
the various shades which compose the color of a panel, as is usually
done in this kind of work; the operation changes only when the glass
cutter hands these sheets over to the man who undertakes the painting.
The sheets of glass are cut according to the lines of the drawing, and
after being well cleaned, they are placed on the paper on the places for
which they have been cut out. If the window to be stained is of large
size and consists of several panels, only one panel is proceeded with
at a time. The glass is laid on the reverse side of the paper (the side
opposite to the drawing), the latter having been made transparent by
saturating it with petroleum. This operation also serves to fix the
outlines of the drawing more distinctly, and to give more vigor to the
dark tone of the paper. When the paper is thus prepared, and the sheets
of glass each in its place, they are coated by means of a brush with
a sensitizing solution on the side which comes into contact with the
paper. This coating should be as thin and as uniform as possible on
the surface of the glass. For more perfectly equalizing the coating, a
second brush is used.

The sensitizing solution which serves to produce the verifiable image is
prepared as follows: Bichromate of ammonia is dissolved in water till
the latter is saturated; five grammes of powdered dextrin or glucose are
then dissolved in 100 grammes of water; to either of these solutions
is added 10 per cent. of the solution of bichromate, and the mixture
filtered.