Drilling. A broken end of hard steel, as, for example, a small file well moistened with the turpentine-and-camphor mixture mentioned under " Filing."
Tubes, to bend or expand into bulbs. For making syphons, soft French flint glass is convenient; or the soft German glass of the chemical apparatus shops may be used. Heated in the upper part of an ordinary gas burner, such tube will soften and can be readily bent, any deposit of soot being wiped off when the tube is cold. In a similar way it may be softened sufficiently for drawing to a fine point. Division at any required place by making a file scratch and breaking, the sharp edges being now rounded by incipient melting in the flame of a Bunsen burner. Rod of similar glass can be divided and the edges rounded in the same way. Blowing into bulbs necessitates a blowpipe for heating, but is easy with a little practice. Those who desire further information on glass-working are referred to M Glass Blowing and Working," by T. Bolas: London, 1898, Dawbarn & Ward.
Glucose (Ger., Glucose, Starkezucker, Traubenzucker ; Fr., Glucose; Ital., Glucosio). Synonyms: Grape Sugar, Dextrose. C6HI206=i8o. There are several kinds of glucose, which is preferably to be considered as a generic name. It occurs either in white crystals or a thick, syrupy liquid, and was used as a preservative in the collodion process, and is also employed in some powder processes.
Glycerine (Ger., Glycerin; Fr., Glycerine; Ital., Glicerina; Lat, Glycerinum). C3H5(OH)3. A peculiar, sweet, viscid liquid, obtained from oils and fats as a bye product in saponification. Specific gravity, 1*260. It is extremely hygroscopic, and its non-drying properties are taken advantage of in photography to prevent the too rapid drying of some substances, and it is also used as a preservative of pyro. It is miscible in all proportions with water and alcohol. It has also been suggested as a re-strainer in developing, its action being probably rather physical in this respect than chemical.
Glycin Developer. See Development and Developers.
Gold (Ger., Gold; Fr., Or; Ital., Oro; Lat., Aurum). Au. 196. A yellow or yellowish-red metal soluble in nitro-hydro-