the toning and fixing bath.

TONING AND FIXING BATH.
Sulphocyanide of ammonium 1 ounce
Water 12 ounces
Chloride of gold 1 to 3 grains

After removing from this bath, the prints are immersed for a few moments
in water, and then rapidly washed.

FORMULA FOR PREPARING THE PYROXYLINE
Nitric acid, sp. gr. 1.30 12 fluid ounces
Sulphuric acid, sp. gr. 36 fluid ounces
1.845
Water 8 fluid ounces
Temperature 130 degrees Fahr.
Time of immersion 15 minutes.

X'S PROCESS (1865). (Secrets of the Uranotype)

_Preparation of the Uranium Compound.--_Precipitate the nitrate of uranium
from its solution by concentrated liquid ammonia. Let settle the
precipitate, decant, and wash in several changes of water. Dissolve it by
heat in pure nitric acid, _taking care not to add an excess of acid._ The
ammonio-nitrate of uranium salt is then crystallized and dried. Mix a
solution of 6 drams of this salt, dissolved in 3 drams of water, to a
solution of 15 grains of silver in 30 minims of water, and crystallize.
This salt is called _ammonio-nitrate of uranium and silver._

SENSITIZING SOLUTION.
Ammonio nitrate salt 3 drams
Alcohol 8 drams
Distilled water 15 drops
Nitric acid, pure 1 drop

_Plain Collodion.--_Dissolve in a small quantity of ether 1 dram of Canada
balsam and 1 dram of castor oil, filter and let evaporate the solution to
the consistency of oil.

Of this, add 10 minims to a collodion made of

Alcohol 10 ounces
Ether 20 ounces
Pyroxyline 220 grains

SENSITIVE COLLODION
Plain collodion 12 drams
Sensitizing solution 6 drams
Nitric acid 2 or more drops

Keep this collodion in the dark, as it is quite sensitive.

PREPARATION OF THE PAPER
Arrowroot, pulverized 1 ounce
Water 32 ounces
Solution of acetate of 10 drops
lead

Heat to 100 deg. Fahr. and then add four ounces of albumen. The paper is
floated on this solution for five minutes and hung up to dry. The sizing
may also be applied with a sponge in the manner often described.

The proofs should be slightly over-printed and, before toning and fixing,
placed for about ten minutes in the following solution:

Distilled water 40 ounces
Acetic acid 1 ounce
Hydrochloric acid 1 ounce

After washing in several changes of