t declaration of his
discovery, but he has since found that a neutral solution of silver is
equally useful in bringing out the picture. Photographic pictures
taken on this paper are distinguished by a clearness of outline foreign
to all other methods.

CHAP. X.

CYANOTYPE--ENERGIATYPE--CHROMATYPE--ANTHOTYPE--AMPHITYPE AND "CRAYON
DAGUERREOTYPE."

The several processes enumerated at the head of this chapter, are all
discoveries of English philosophers, with the exception of the third
and last named. Anthotype was first attempted by M. Ponton a French
savan, although it was reserved to Mr. Hunt to bring the process to its
present state. The "Crayon Daguerreotype" is an improvement made by J.
A Whipple, Esq., of Boston.

I. CYANOTYPE.

So called from the circumstance of cyanogen in its combinations with
iron performing a leading part in the process. It was discovered by
Sir John Herschel. The process is a simple one, and the resulting
pictures are blue.

Brush the paper over with a solution of the ammonio-citrate of iron.
This solution should be sufficiently strong to resemble sherry wine in
color. Expose the paper in the usual way, and pass over it very
sparingly and evenly a wash of the common yellow ferro-cyanate of
potass. As soon as the liquid is applied, the negative picture
vanishes, and is replaced by a positive one, of a violet blue color, on
a greenish yellow ground, which at a certain time possesses a high
degree of sharpness, and singular beauty of tint.

A curious process was discovered by Sir John Herschel, by which dormant
pictures are produced capable of developement by the breath, or by
keeping in a moist atmosphere. It is as follows.

If nitrate of silver, specific gravity 1.200 be added to ferro-tartaric
acid, specific gravity 1.023, a precipitate falls, which is in a great
measure redissolved by a gentle heat, leaving a black sediment, which,
being cleared by subsidence, a liquid of a pale yellow color is
obtained, in which the further addition of the nitrate causes no
turbidness. When the total quantity of the nitrated solution added
amounts to about half the bulk of the ferro-tartaric acid, it is
enough. The liquid so prepared does not alter if kept in the dark.
Spread on paper, and exposed wet to the sunshine (partly shaded) for a
few seconds, no impression seems to be made, but by degrees, although
withdrawn from the action of light, it developes itself spontaneously,
a