FIXING THE DEVELOPED IMAGE.
This is accomplished by pouring over the surface of the plate sufficient solution of hyposulphite of soda (p. 15) to thoroughly cover it, this will dissolve out the unaltered iodide of silver, and give us a clear and bright picture, in which the deep shadows should be as transparent as the glass itself, and the high lights as dense as a piece of metal, the intermediate tones assuming their proper positions according to the intensity of the light that was concerned in their formation.
When the whole of the yellow iodide of silver is removed, the fixing solution may be thrown off, and the plate must be treated with an abundance of water; too much cannot well be given at this stage, as the hyposulphite adheres with great tenacity to the plate, even after a good washing. The back of the plate must be washed as well as the front, for I have found that a neglect of this precaution has ruined many a fine negative; the hyposulphite remaining at the back finding its way by capillary attraction to the surface, and once there, its destructive qualities are sure, sooner or later, to render themselves evident.
The picture being thoroughly washed, and either dried spontaneously or by the fire, has only to be covered with a film of varnish. And now comes the last operation, of