This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Cyanide of Potassium
Caution. Cyanide of potassium is a deadly poison. Both the bottle containing the cyanide crystals and the cyanide solution should be labeled and kept out of reach of children. Where the hands are scratched or contain any sores, they must never come in contact with cyanide, otherwise the system might become poisoned. Extreme care must be used in handling the plate in this bath, and the fingers should be kept from the solution by-using a rubber, glass or silver dipper.
900. In place of cyanide of potassium, the following formula can be used for fixing:
Washing Glass To Be Used For Negatives. In order that you may be sure that the glass employed is chemically clean, place it in a solution of caustic soda or potash, for say five minutes. When the glass is coated with film - possibly an old exposed negative - it must remain in the potash for a number of hours, and for this purpose you should have an earthen dish or a solid rubber tray, one large enough to receive a number of plates at one time.
902. Another method for cleaning old dry plates for wet plate work, is to make up a strong solution of commercial sulphuric acid, placing the plates in this solution. It is advisable to wear rubber gloves when handling the plates. Where perfectly clear glass is used, a few minutes' soaking in the soda or potash will be found sufficient. After the plates have become thoroughly rinsed and cleansed, whether old or new, they should then be placed in a 10% solution of commercial nitric acid and allowed to remain for about an hour; finally, carefully rinse and set in the negative rack to dry.
Preparing The Plate To Receive The Collodion. When dry, the plate is usually ready to receive the collodion; but, while the collodion may be applied direct to the glass plate without any previous preparation, there are cases where the collodion will not readily adhere to the plate. Should you meet with such difficulty it will be advisable to prepare the plate with albumen before collo-dionizing it.
Albumenizing The Plate. Prepare the albumen as follows: Place into a clean dish 32 ounces of pure water. Add to this the white of one egg. Beat the egg well, mixing it with the water. Then add 10 to 15 drops of aqua ammonia, and again stir well; then filter into a clean bottle. To albumenize the plate you flow the albumen on the plate exactly the same as you collo-dionize it. (See Paragraph 906.) The plates are, of course, thoroughly cleansed and dried before this is done, and just before the albumen is applied the plate is carefully dusted with a camel's-hair duster. A sufficient number of plates for a day's work may be albumenized at one time, and after albumenizing they are placed in a rack to dry, in a place free from dust or fumes. The albumen must be thoroughly dry before applying the collodion. It is advisable to try collodionizing the plate without albumenizing it. Should the film slide or break from the plate you should apply the substratum coating (albumen) to another sheet of glass, then collodionize it.