upon the surface in the same manner as the gilding solution.
If the solarization be very deep, apply the lamp beneath,
and warm the plate a trifle. Now pour off, and, without rinsing,
apply the gilding. The whole operation must be quickly performed,
or the chlorine soon attacks the shades of the picture.
When properly done, however, the solarized parts are restored
to a clear, transparent white.

Electro, or Cold Gilding.--This process I have adopted, and it
produces exceedingly beautiful impressions for the stereoscope,
adding a great charm to the pleasing effect of that instrument.
It also possesses a pretty and curious effect on views.
It is easy of trial, and may be used by dissolving one gramme
of chloride of gold in half a litre of ordinary water, and thirty
grammes of hyposulphite of soda in another half litre of similar water;
then pour the solution of chloride of gold into that of soda,
by little and little, agitating it exactly as in M. Fizeau's preparation,
of which there is but a variation.

When you wish to use it, pour some into a plate, or any other vessel
of the same kind, sufficient to cover the proof; then, after having
added to it a drop of ammonia, immerse the plate in it as soon
as you take it out of the mercury-box, after having wiped its back
and edges, and agitate the mixture quickly from right to left,
so as to dissolve rapidly the coating of iodide of silver as usual.
As soon as the plate appears white, cease all rapid motion,
but continue to give it a slight undulating one; for if it were allowed
to remain still for only a few minutes, the proof would be clouded.
By little and little, the surface of the plate takes a yellow tint,
which darkens more and more, approaching to bistre. You stop therefore,