| PLAIN COLLODION. | |
|---|---|
| Alcohol | 12 ounces |
| Ether | 4 ounces |
| Pyroxyline | 80 grains |
| SENSITIVE COLLODION. | |
|---|---|
| Plain collodion | 1 ounce |
| Nitrate of uranium, pure | 30 grains |
| Nitrate or silver | 5 grains |
Add the uranium first, and as soon as it has dissolved all that [pg 69] it can, add a grain or two of soda, and when settled pour off the supernatant collodion and add the silver.[14] To coat the paper with collodion, use a board with a handle beneath, such as is used by plasterers. On this place a sheet of paper, the edges being turned up about the sixteenth of an inch; this enables the whole of the sheet to be covered without spilling the collodion or allowing it to run on the back of the paper.
There is a marked difference in the appearance of the prints when they leave the pressure frame. Some samples of collodion cause the picture to print of a beautiful green, others of a rich brown, and some of a yellow or orange tint. The last take the longest of all to tone, and difficultly assume the tint of well toned silver prints,[15] those printing to green or brown tone very rapidly.
After printing the pictures are placed in diluted sulphuric acid, 1 to 30 of water, until the high lights are perfectly clear and white; this takes from ten to fifteen minutes. After washing well under a stream of water, they are placed in 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. 1.845 | 36 fluid ounces |
| 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.