PRINTING.
The negative, with its back carefully cleaned, is now laid, film up, in the print ing frame, and the packet of tissue opened in subdued light. The tissue is not so sensitive as to need to be kept in the dark ; but being more sensitive than ordin ary silver paper, less light should be used. The tissue is almost black on one side and yellow on the other; the black is the sensitive side, and should, of course, be in contact with the film. If an assorted packet of tissue is purchased—that is, one containing various colours, such as en graving black, standard brown, sepia, red chalk, and blue—it will be found that the surface in each case differs only slightly ; the blue and the black will scarcely be distinguishable, whilst the red chalk will appear a brown. The makers, to prevent mistakes, usually stamp the back with the name of the colour. From this it will be seen that pictures by the carbon process may be of any colour. The colours men tioned are generally in stock, but manu facturers are always willing to make up tissue to match any colour provided a sufficient quantity is ordered. The colours
named, however, give sufficient choice for all purposes. A selection must be made to suit the character of the subject. En graving black or standard brown are suit able for general work, the warm colours for fancy pictures, sunset effects, etc., and blue for moonlight scenes.
and The former is shown by Fig. 292, and consists of a metal box with lid containing a wooden block hol lowed out in the centre to take a coil of P.O.P. or sensitive albumen paper. This passes over the top of the block under wire loops beneath the opening, coming out at the slot at the side. The circle is painted a medium brown, and it is to this shade which the paper has to darken two or more times, according to the den sity of the negative. The latter consists,