PHOTOGRAPHIC TINTS AND COLORS.

New Zealand Times, Volume XXXII, Issue 5120, 21 August 1877, Page 3

PHOTOGRAPHIC TINTS AND COLORS.

Photographers, says an exchange, are certainly very clever people. The most recent feat that they seem to have successfully accomplished is the reproduction of the blue notes of the Bank of Prance and the red ones of some of the Scotch banks. Both red and blue have for a long time past been deemed sufficient to baffle such professors of the black art as strive to compete with Government and bankers in the production of these valuable documents. The National Bank at Vienna has, however, it appears, lately been much troubled with forgeries of the familiar cobaltblue notes of the French, while from Scotland we bear of genuine and imitation notes being pinned together, so like one another as to deceive all but the most experienced. The colors are not, of course, reproduced by the camera as they appear to the eye, for the supposed safety in the employment of blue and red upon bank notes was that the former comes out very light in a photograph, and the latter very dark. Science has, however, recently shown that the effect of color upon a sensitive plate may be increased and diminished at will. A German chemist has plainly demonstrated that by tinting the collodion used in taking a picture, or- by employing glass plates of different colors, objects may be vividly photographed which under ordinary circumstances would be only faintly depicted. At the Bank of France, strange to say, whose notes have been so freely copied, there is a photographic establishment where a good deal of useful work is done in the way of discovering forgeries, the sharp eye of the camera being a most searching detective. The slightest erasure upon the surface of a cheque, or the alteration of a figure which is imperceptible to the eye, is. at once made apparent by photography. Color, it would seem, is after all but very little protection, for the English bank note is very rarely imitated, and the same may be said of the' German paper money, which is printed in black and white. A combination of colors, laid one over another, has been suggested, and would probably render the difficulty of copying by means of the camera almost insuperable ; but : it certainly behoves us in these days of experiment and discovery to be very careful in our estimate of the impossible. '