On pages 32, 33, and 34, will be found complete directions for printing upon silver-albumenized paper, but here it is proposed to give concise directions for obtaining prints from a negative in other colours than those given by albumenized paper, such as blue, black, sepia, brown» red chalk and various shades of purple and black. Ferroprussiate or Blue Prints.
By this process bright-blue prints on a white ground are obtained, and although not pleasing to all they afford an agreeable relief to the monotone of albumen prints, and it is especially suitable for sea-scapes. It is also the easiest of all printing processes, easier even than that with silver paper, as when the print is taken no operation of toning is required. The paper can be bought very cheap, and of a bright yellowish green colour; it will keep almost indefinitely, if kept perfectly free from light and damp. The paper should be cut to the required size and placed in the printing frame with the coloured size next to the negative; the back being placed in position the frame is exposed to light; and the print examined from time to time till it is seen that the whole of the detail is visible in an olive bluish green shade. The paper should now be removed from the frame and,washed in water or. under a tap, when it will be seen that the image will turn bright-blue and the ground of the paper turn white, - the paper should be washed till the drippings from it are quite colourless. Should the paper from having been improperly kept or overprinted show a bluish tinge in the whites, it can be dipped in a bath of ammonia, - one drachm to the half-pint of water - and then after rinsing once in a bath of hydrochloric acid of the same strength, the print should be allowed to dry, when it can be mounted in the ordinary way.