BOTTLES. —The selection of conven ient bottles for the various chemicals used in photography requires some little thought. Acids should be kept in glass-stoppered bot tles (Fig. 73), and the stoppers rubbed round with a little vaseline. This renders the stop per perfectly air-tight, and prevents it from becoming fast in the bottle. The same applies to ammonia, and other volatile coin applies pounds. Fluoric and other glass-destroying acids should be kept in bottles made of gutta percha. Solids should be kept in bottles, with wide mouths (Fig. 72) to facilitate the removal of large lumps. For coating with gelatine or collodion emulsions, the .
substance should be placed in a convenient bottle. The most suitable are the hock or Rhine-wine bottles, for the reason that the long and gradually sloping neck prevents the formation of air bub bles. Their non-actinic color renders them especially suitable for sensitive emulsions.
All chemicals sensitive to light should be placed in yellow or non-actinic colored bottles.
For convenient dropping bottles, see Dropping Bottle.
BOUDOIR.—This name has been given to a standard size for portrait work. Boudoir mounts measure 5 x 8% inches.
BOXES.—For storing unexposed plates these should be per fectly light-tight, and made of such wood or material as will not affect the most sensitive plates. To prevent the plates from com ing into close contact with each other the boxes are usually fitted with grooves into which the negatives slide. Fig. 74 shows the usual style of boxes em ployed for storing plates, negatives or lantern slides.
BRASS WORK.—The brass work of the interior of the lens and the diaphragm stops should be kept a dull black, to prevent the reflection of light upon the sensitive surfaces. For a suitable black, see Blacking and Black Varnish.
BREADTH.—This term is used by artists to denote the proper balance and relative value that should exist between the lights and shades of a picture. To secure breadth, a principal part must be made predominant, and parts that are secondary should be kept in due subordina tion, and thus detail in its technical sense is opposed to breadth.