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CHAPTER VIII. GELATINE EMULSION PROCESSES-PRELIMINARY.
WE cheerfully acknowledge, and proudly assert, that in the markets of every civilized country, plates prepared for photographic purposes, with gelatine emulsion, are found, excellent in their qnalitie~, and suitable for every purpo~>e for which they may be intended. We do not expect that any person making emulsion on a small scale, or with limited appliances, will produce plates of such even perfection as those of professional plate-makers; and we are pretty confident that the amateur plate-maker will not save any money by his plate-making. But we urge upon every one who wishes to work with intelligent comprehension of what he is doing, and every one who has the ambition to further photog1•aphic knowledge, by his own efforts to acquire a perfect knowledge of, and facility in, the production of gelatine emulsion, and the preparation of plates, or paper, therewith. No treatise on modern photography would, in our opinion, b~ worthy the name, unless it showed evidence of an attempt, at least, to initiate its readers into this, the most important photographic process of the present day. Our modest directions shall be given, to the best of our ability, in such a way that any intelligent pe1·son following them, shall be able to produce a good emulsion, and with a little practice, to prepare good plates; at any rate, so that any person reading them with moderate attention shall grasp the facts guiding our practice, and the conditions necessary to ensure success. The change of " vehicle " from collodion to gelatine carries in its train more important considerations than might, at first sight, be expected. In a collodion emulsion the collodion is practically a purely mechanical menstruum, in a gelatine emulsion the part played by the gelatine is more, by far, than mechani-