93 



alcohol, the solution digested with oxyd of lead, filtered, and the- 

 liquid brought to dryness. White, bitter powder, soluble in 

 water and alcohol, insoluble in ether, converted by digestion with 

 diluted sidphuric acid into sugar and other prodiicts. 



Globiilaria Tannic Acid^Cie H12 Ok. In the leaves of 



Globularia Alypum. Is precipitated from the aqueous solution of the 

 alcoholic extract by digestion with oxyd of lead, (^ee Globularin.) 

 Divide the precipitate in alcohol, decompose with diluted sulphuric 

 acid, shake the green-brown liquor with a little carbonate of lead 

 and precipitate with alcoholic acetate of lead. Isolated by sul- 

 ])huret of hydrogen, it is only known in solution which imparts a 

 dark-green colour to chloride of iron. 



Glucose = Grape Susar. 



[GlucOSids are organic compounds of a high atomic weight and 

 great chemical complexity. They are resolved by heating with 

 dilute acids, or sometimes even when left in contact with certain 

 protein-substances, imder assimilation of water, into sugar (fer- 

 mentable or not), and one or more other products, generally an 

 essential oil or a resinous body. They also in most cases exhibit 

 the following properties : — They are crystalline or amorphous, 

 neutral, or slightly acid ; without odour, of a bitter or acrid taste ; 

 fusible, but without sublimation, and carbonised hj prolonged 

 heating ; they dissolve easily in alcohol, less so in water, sparingly 

 or not at all in ether, under decomposition in alkalies with yellow, 

 and in concentrated sulphuric acid with blue, \dolet, or red colour. 

 — F. V. M.] 



Gluten. A substance which has been formerly considered as a 

 peculiar proximate constituent of the vegetable kingdom, but 

 which is now proved to be only a mixture of difierent protein 

 substances. It occurs especially in the seeds of the cereals and of 

 leguminous plants. It is obtained best by kneading wheat-flour 

 under cold water until the water passes from it clear and without 

 a milky appearance (by taking up starch). When fresh, it is of a 

 gi'eyish-white, very viscid, glutinous, elastic, tasteless, of insijiid 

 odour; when dried, it appears grey-yellow, horny, brittle, mollifies 

 in cold water and dissolves a little ; the solution curdles at 62°; 

 by boiling with water it becomes hard and insoluble. Hot alcohol 

 with di-aws from it so-called gliadin, which is itself a mixture of gluten,, 

 mucin and giim, and leaves undissolved the so-called vegetable 

 fibrin as a brownish-grey matter, containing sulphur and nitrogen. 

 (Some authors believe the latter to be coagulated albumin). 



Glutin. Peculiar protein substance, ingredient of gluten. By 

 boiling gluten with alcohol, a solution is obtained which yields on 

 evaporating the so-called gliadin, i.e., a mixtui'e of Glutin and 

 mucin and gum. By distilling the solution with water, most of 



