time of printing materially; that a greater excess of the citrate causes
the whites to become badly stained by the iron, while a still greater
excess of the citrate, in a concentrated solution causes the sensitized
paper to change without exposure to light, and to produce a redder blue
or purple, which does not adhere to the paper, but may be washed off
with a sponge. I have found that the cheapest method of reproducing
inked drawings that have been made on thick paper is not to trace them,
but to print the blues from a photographic glass negative; and also,
that the dry plate process is well adapted to such work in offices, when
one has become sufficiently experienced. Printed matter can also most
easily and inexpensively be reproduced by the same means, when a small
issue is required on each successive year. For the reproduction of
manuscript by the blue process, the best plan that I have found has been
to write the manuscript upon the thinnest blue tinted French note-paper,
with black opaque ink--the stylographic ink is very good--and,
afterward, to dip the paper into melted paraffine, and to dry the paper
at the melting temperature. This operation, if cheaply done, requires
special apparatus. For positive printing from the glass negative, I use
a multiple frame, by the aid of which I can print from 16 negatives at
the same time, upon a single sheet of paper. This frame is
interchangeable with the one that contains the plate glass. The
negatives are so arranged in the frame that the sheets can be cut and
bound, as in the ordinary process of book binding. The time required for
exposure, when printing from glass negatives, varies with the negative;
and, in order to secure satisfactory results with the multiple frame it
is necessary to stop the exposure of some, while the exposure of others
is continued. I insert wooden or cloth stoppers into the frame for the
purpose of stopping the exposure of certain negatives. When paraffined
manuscript is to be printed from, I find it convenient to have it
written on sheets of small size, and to have these mounted upon an