Ozotype, Gum-Ozotype. The ozotype process is a new method of carbon or pigment printing, introduced to general notice since the publication of the last edition of The Dictionary of Photography, and this process has rapidly become popular. The inventor and patentee of the ozotype process, Mr. Manly, has written a lucid handbook, and has given demonstrations in London, so that certain difficulties which were first encountered have practically ceased to trouble those who work with ozotype. Mr. Manly's "Handbook of Ozotype " (price is.) is published by Hazell, Watson, & Viney, Ltd., and contain all necessary information.
The ozotype process may be considered as remotely an out-come of the chromatype processes (see Chromatype) of nearly fifty years ago, in which the faint image obtained on paper, sensitised with a pure or mixed bichromate solution, is so treated as to make the weak image gather intensity ; or perhaps a nearer ancestor of the ozotype process in the Mariotype (see Mario-type) of 1873, in which the faint image on bichromated paper is built upon by its tendency to induce local insolubility in carbon tissue brought into contact with it.
A characteristic feature of ozotype and one which forms the basis of Mr. Manly's patent is the use of a special sensitising solution containing not only a bichromate, but also a manganous salt. This solution is supplied quite ready for use by the Ozotype Company of 1, Weedington Road, Kentish Town, London. By the use of a manganese salt in conjunction with the bichromate a very vigorous and distinctly brown image is obtained on the prepared paper by exposure, this making the regulation of the exposure as easy as it is in the case of any ordinary printing-out paper. In this case a brown chromate of manganese appears to be formed, and this compound seems to be specially active in producing insolubility of the plaster of pigmented gelatine, or the layer of pigmented gum which is subsequentlyi brought into contact with the print. 'Still, plain bichromate solutions or bichromate solutions containing mer-curous nitrate may be used, as Mr. Haddon has pointed out.
Sensitising the Paper for Exposure. Any ordinary paper of good quality may be employed for ozotype, but naturally there will be a general preference for the standard drawing papers. First lay a protective sheet of clean paper on a table or drawing