Bellows Bibliography of Photography
by exposure to air and light, and cast into flat round cakes. In certain processes of carbon printing it is important to obtain pure wax; this being difficult unless the original comb can be obtained from a beekeeper who does not fit his hives with the artificial combs or bases now used so largely to increase the output of honey.
Bellows. That portion of the camera which unites the back and front portions is called the bellows, and is usually con-structed of calico or leather. For those anxious to make their own bellows full instruction will be found in The Amateur Photographer for July 10th, 1891, p. 25. There are three principal varieties of bellows in use - the square, the oblong, and the conical. The first entails most weight, the second is almost obsolete, and the third the most prevalent and lightest. The question as to which is the best is a matter of personal opinion, but when the camera is to be used with a very wide-angle lens a conical bellows may prove obstructive, owing to the unequal stiffness of the folds.
Benzine (Ger., Benzin; Fr.# Benzine; Ital., Benzina). Synonym: Benzol. C6H6 = 78. A colourless liquid, with characteristic smell resembling coal gas, obtained commercially by fractional distillation of coal tar, between 360 and 1500 C.; it is purified by a second distillation at 8oo C, and should crystallise at oo C. It is insoluble in water, but soluble in all proportions in alcohol and ether. It is a solvent of all fixed and volatile oils, and greasy substances generally. It boils at about 85oC, and at ordinary temperature gives off a vapour which is extremely explosive. It is used in photography as a solvent in encaustic paste, for the preparation of matt varnishes, and as a developer or solvent of bitumen in certain photomechanical processes not to be confounded with Benzoline (q.v.).
Benzoline. A light petroleum spirit used for burning in lamps. It is far inferior in solvent power to true benzole or benzine, and will seldom replace it in photographic operations.
Berkeley's Sulpho-Pyrogallol. See Sulpho-Pyrogallol.
Bibliography of Photography. The number of photo-graphic books which have been published is much greater than