The ferrotype and how to make it - The Grian Press

168 THE FERROTYPE,
length of time required for exposure. I began to
cast about for means to shorten the time of ex-
posure.
Having already the quickest working Collo-
dion, etc., that I supposed it possible to produce, I
arrived at the conclusion that I 'could do nothing
in that direction, but must direct my efforts to
make the prism more effective as a reflector. I
had, I supposed, been using only its refractive
power as yet. One day, as an experiment, I removed
the prism from the case, and, taking out
the velvet, I inserted in its place a piece of white
card- board, and, to my surprise, on again trying
the exposure, I found that by this simple means
I was enabled to reduce the time of exposure
about one-half, and got quite as perfect an image.
This surprised me, as I knew that the surface of
the card-board possessed a very low reflecting
power, and also that its surface must be very un-
equal, but it seemed that the prism corrected any
defect arising from such inequalities of surface.
In this way I was at once put on the right
track to the long-desired object.
Taking my prism to the silver plater, I had a
coating of metallic silver deposited upon its
largest surface, which I caused to be covered
with a strong varnish to protect it from friction,
etc. I again placed it in its case, and, as may
be imagined, with trembling anxiety prepared to
try again its reflecting powers.
Upon coating a plate and subjecting it to an