GLYCINE, OR GLYCIN (Fr., Glycine ; Ger., Glycin) A developer, known also as paraoxyphenylgly cin, having the formula OH COOH. It appears in the form of glistening grey powder, which, when carelessly kept, turns to a brownish black and loses its developing powers. The powder is insoluble in plain water, but soluble in a solution of sodium sulphite, or on the addition of an alkali. It is a slow-working developer, having a factor of 7, and works after the manner of ferrous oxalate ; it has the advan tage of giving good clear negatives with little or no fog, and good density. It is widely used for stand and tank development and for the repro duction of black-and-white subjects ; it may be used in a one-solution or two-solution form.
One-Solution Developer Hot water . . 3o oz. i,000 ccs.
Sodium sulphite .
45 fl Potassium carbonate 2 go Glycin . . . /7 18 The above is ready for use.
Another one-solution formula gives a stock solution in the form of a cream, and is known as Hiibl's Stock Glycine Solution Sodium sulphite . zi oz. 688 g.
dissolved in Hot water 4 )7 1,000 ccs.
then add Glycine . . . 1 275 g.
Heat to boiling point, and add Potassium carbonate . 5 oz. 1,375 g.
Add the potassium carbonate gradually in small quantities on account of the carbonic-add gas.
When cold, this forms a thin paste ; when required for use, shake and dilute i part with 12 parts of water, using more water for soft development and less water for hard develop ment. For stand development, mix with so to 55 parts of water.
Two-Solution Developer A. Glycine . . 38o grs. 44 g.
Potass. carbonate . 144 16.5 Sodium sulphite . 5 oz. 275 Water . . . 20 i,000 ccs.
B. Potass. carbonate . 2i 137 g.
Water . . . zo 1,000 ccs.
For use, mix equal parts of A, B, and water. Potassium bromide is added in cases of over exposure.
Messrs. Newton and Bull have recommended glycine as a developer for all isochromatic plates, as follows : Glycine . . . 192 grs. 18 g.
Potass. carbonate . 2 oz. 88 Sod. sulphite (anhydrous) 24o grs. 22 Potassium bromide . 12 1 Water to . . . 25 1,00o ccs.
Development is controlled by time, using a factor of 6.
In process work, glycine is an excellent developer for collodion emulsion and for process dry plates, but it is expensive compared with hydroquinone, which is more generally used.