cribed, immerse it for a few minutes in a
solution of nitrate of cobalt and dry it without washing. Fix then in a
solution of sulphate of iron at 20 per cent. of water and 4 of sulphuric
acid. Wash and dry before the fire.

Violet Prints.

Prepare the paper in the uranium bath, expose, wash and develop in a
solution of chloride of gold, 1:200, until the proof has assumed a fine
violet color. Wash in several changes of water.

Blue Prints.

Sensitize the paper with a red prussiate of potash solution at 20 per 100.
Let dry, expose until the proof is slightly blue; immerse it for five or
ten seconds in a saturated solution of bichloride of mercury, wash only
once and immerse in a solution of oxalic acid--saturated when cold--heated
to about 55 deg. C. Wash in three or four waters and let dry
spontaneously.

Black Prints.

Float the paper on a mixture by equal volumes of a solution of iron
perchloride and another of uranium nitrate, each at 10 per 100 of water.
Expose and develop on a saturated solution of gallic acid.

DR. T.L. PHIPSON'S PROCESS (1861).

Take a solution of perchloride of iron and, having precipitated the
peroxide with ammonia, collect the precipitate on a filter and wash it
with boiling water. Add the precipitate in excess to a warm solution of
oxalic acid. A beautiful emerald green solution is obtained, which must
be a little concentrated by evaporation and then set aside in a dark room
for use. The paper is floated for ten (?) minutes upon the green solution
of ferric oxalate, to which has been added a little oxalate of ammonia and
hung up to dry in the dark.

Expose under a negative for from ten to twenty minutes, according to the
weather, and wash well the paper with rain water. Spring water will not
do on account of the lime it may contain, which will form oxalate of lime
in the paper (insoluble). When all the non-decomposed oxalate is washed
from the proof, a feeble image of oxalate of protoxide of iron, scarcely
visible, is left on the paper. To develop it and to obtain the vigor, the
tone and color of silver prints proceed as follows:

Plunge the proof for a little while in a (weak) solution of permanganate
of potassium to which a few drops of ammonia have been added; in the bath
the image becomes brown and distinctly visible. It is then withdrawn and
immersed in a solution of pyrogallic acid for half an hour, after which it
is washed and