Bromo-Iodized Collodion for Positives.—No. 2.
| Plain collodion | 10 | ounces. |
| Iodide of potassium | 30 | grains. |
| Bromide of ammonium | 20 | " |
Enough of the double iodide of potassium and silver to give the coating a cream color when it comes from the silvering solution. It will take from one to three drachms. Or this last may be omitted, and a few drops of a saturated solution of dry iodine in alcohol may be added. Either of these plans have been successful in my practice.
Remarks.—The iodide of potassium being insoluble in the collodion, it should be first dissolved in as little water as possible; i. e., take the quantity, 30 grains, put it into a one-ounce graduate, and with a glass rod stir it, adding water, drop by drop, only until all of the salt is dissolved. Then it may be poured into the collodion, and there will be a white powdery precipitate.
The bromide of ammonium will dissolve in the collodion, and can be put into it. When all of the accelerators are in, it should be well shaken, and then allowed to settle and become clear. When wanted, a sufficient quantity may be poured into a vial (see [Fig. 34]) for use, and the main or stock bottle should not be disturbed oftener than necessary. This last collodion is not as durable as the first, but is less trouble to prepare.
Bromo-Iodized Collodion for Negatives.
IODIZED COLLODION FOR NEGATIVES
| Plain collodion | 8 | ounces. |
| Iodide of potassium (dissolved as per [page 62]) | 24 | grains. |
| Bromide of ammonium | 16 | " |
This collodion should be allowed to stand and settle twenty-four hours before it is used: when wanted, it should be poured off into a collodion vial. The more free the collodion is from sediment and small particles of dust or undissolved cotton, the softer and more perfect will be the impression it makes.