of
the plate.

I would remark, that so far as my experience has gone, I consider good
rouge fully equal to any other polishing, material for the last or
finishing polishing; consequently I shall not take up my space in
enumerating any of the great variety that find few advocates.

Why Rouge is to be preferred.--"Because it burnishes better, and
because it assists in fixing the layer of gold, rendering it less
susceptible of being removed in scales when heated too much."

Rotten Stone.--"Purchase the best ground rotten stone of the druggist,
put a few ounces at a time in a wedgewood or porcelain mortar, with
plenty of clean rain water. This should have about forty drops of
nitric acid to the quart. Grind well, and after letting the mortar
stand two minutes, pour into a third. After remaining undisturbed
eight minutes, finally pour off into a fourth to settle. Rinse back
the sediment in the second and third, and grind over with a new batch.
Repeat the operation till you have all in the fourth vessel. Let this
stand several hours, and pour off the water very carefully. Set the
deposit in the sun, or by a stove to dry. When perfectly dry,
pulverize, and it is ready for use. With a little trouble you will
obtain in this way a much better article than can generally be bought
of dealers. For the last washing, alcohol, or a mixture of alcohol and
water, is preferable."

Potassa Solution.--The use of a solution of potassa in the preparation
of the plate was suggested in the early history of the Daguerreotype.
It was thought to possess some peculiar property for improving the tone
of the impression. It is used for moistening the rotten stone in
polishing the plate, and may be prepared by putting about an ounce and
a half of alcohol in a close bottle, and add half a stick of caustic
potash. This will soon become of a deep red color. For use, fill your
small bottle, having a quill in the cork, with alcohol, and add a few
drops of the above, or enough to change it to a bright orange or
saffron color.

A Substitute for the Hyposulphite Solution.--M. DAGUERRE recommends the
use of a solution of salt water for removing the coating off the plate.
I found this of some service at one time during my travels. My
hyposulphite bottle got broke and its contents lost, so as only to
leave enough for preparing gilding. I resorted to the use of salt
solution, and found it to answer well. Make a saturated solution of
salt in w