Indian ink or ivory black
Whatever backing is used, it must be removed before develop-ing. Debenham has suggested the use of caramel or burnt sugar and sienna; it has been found to be the most effective and easily prepared of any, and is made with
Mucilage ... ... ... ... ... i oz.
Caramel ... ... ... ... ... I ,,
Burnt Sienna in powder ... ... ... I ..
Mix in a mortar; distribute this over the back of the plate with a roller squeegee or pad of lint. Cornu recommends a mixture of 6 parts of oil of cloves, and I part of oil of turpentine made into a paste with lampblack.
Bain Marie. A water bath, similar in principle to the ordinary glue pot.
Balance, for weighing. See Weighing and Measuring.
Balance of Effect. A term used in composition to denote the proper relation of lines and lights and shadows, so as to secure harmonious and symmetrical pictures. The subject is much too comprehensive to treat of here, H. P. Robinson's " Pictorial Effect in Photography " being the best guide on the subject.
Balloon Photography. As early as 1858 Nadar of Paris obtained a photograph of the earth below from the car of a balloon, and during the American war of 1861-2, photography from balloons was practically applied to warfare. Since that date numerous experiments have been made, both with captive and free balloons, to obtain results which might be of value in warfare. The attempts have proved that such work is not only possible, but may prove of value.
Balsaming, Re-, of Lenses. In order to reduce reflection and consequent degradation of image, those contact surfaces of lenses which are ground to the same curve are usually cemented