predominates ; iron (ferric) and lead being especially ready to form basic salts.
Bas-relief, Photographic See Sculpture, Photo-graphic.
Bath. This term is used indiscriminately to describe dishes and other vessels, and also the liquids which are used in the same. The vessels are made of various materials, such as porcelain, glass, ebonite, celluloid, etc. The only term which requires explanation in connection with the liquids is that which is frequently used when speaking of the strength of a bath : it is customary to say, " a 60, 50, or 48, etc., grain bath " - this means that 60, 50, or 48 grains of any chemical are contained in each ounce of the liquid.
Beach's Developer. Named after its inventor, Mr. F. C. Beach, of New York. It is made as follows : -
Hot distilled water... ......... 2 ozs.
Sulphite of soda ... ......... 2 ozs.
When cold add
Sulphurous acid ... ... ... ... 2 ozs.
Pyrogallol ... ... ... ... ... 7 oz.
Carbonate of potash ......... 3 ozs.
Sulphite of soda ... ...... ... 2 ,,
Water ...... ......... 7 ,,
Dissolve the salts separately and mix. For a plate having had the normal exposure, mix the pyro and potash solutions in equal proportions, using 1 dram of each to every 1 oz. of water; for under-exposure, use more of the potash solution, and vice versa.
Beechey's Emulsion Process. See Collodion.
Beeswax (Ger., Wachs; Fr., Cire; Ital., Cera). This is obtained from the honeycomb of the bee, and is a yellow mass breaking with a granular structure and of pleasant smell. It should be entirely soluble in hot oil of turpentine, and is in-soluble in alcohol and water. White wax is the above bleached