Printed Matter and Photographic Plates

Abstract

IN connection with this subject it does not appear to be generally known that photographic negatives, after they have been developed and fixed, and especäally if they have been intensified by means of the bi-chloride of mercury and ammonia process, are often strongly impressed by prolonged contact with printed matter. I first observed this many years ago, and have a large number of negatives in my possession which show the effect very strongly, I enclose a photographic negative taken by myself in 1882, which has remained since 1886 wrapped up in the accompanying advertisement sheet of the Electrician. As will be observed, the greater portion of the print in contact with the film is clearly legible. It is, however, worthy of note that it does not appear to be the printer's ink in this case that has produced the chemical action, but rather the paper itself, or some ingredient therein. Those portions of the film protected from contact with the paper by the ink have retained their original colour, while the other portions not so protected have become very considerably bleached. The printing on the side of the paper removed from the film does not seem to have had any effect.