of the subject before gilding, as this last injures the plate for
another impression. First, light your spirit-lamp, then with your
plyers take the plate by the lower right-hand corner, holding it
in such a manner that the plyers will form in a line with the upper
left-hand corner; pour on, slowly, the hyposulphite solution,
slightly agitating the plate, until all the coating is dissolved off;
then rinse off with clean water, and if it is not to be gilded,
dry by holding the plate perpendicular with the bottom left-hand
corner lowest, and applying the blaze of the spirit-lamp to the back,
at the same time blowing gently downward on the face of the plate.

The hyposulphite solution should be often filtered through a sponge,
and it will answer for a great number of washings. Yet it is observed that
the mercury collects in this solution in small globules; these often come
in contact with the plate, causing white spots, which spoil the impression.
They should be guarded against, and the solution renewed. Again, in order
to prevent streaks or scum on the surface of the plate, it is necessary
that the coating should be removed with a good degree of uniformity.
I find in practice that the hyposulphite of soda in our market varies much
as regards strength, and consequently the rule to be adopted is to make
a solution of sufficient strength to remove the coating in about ten seconds.
I am aware that it may be said that this strong solution would have a tendency
to injure the impression by destroying in a measure the sharpness of outline.
To meet this, it need only to be said that the preventive is, to not let
the solution rest on the surface of the plate for a longer time than is
absolutely necessary, and then it should be drenched copiously with water;
hence a chemical action upon the image is prevented and the general
operation facilitated. This plan is adopted by our first operators with
the greatest success.