684 GLYCERINE 



Experiments have not yet explained how gelatine is formed from skin by ebullition. 

 It is a change somewhat analogous to that of starch into gum and sugar, and takes 

 place without any appreciable disengagement of gas, and even in close vessels. Gela- 

 tine, says Berzelius, does not exist in the living body, but several animal tissues, such 

 as skin, cartilages, hartshorn, tendons, the serous membranes, and bones, are suscep- 

 tible of being converted into it. See GELATINE. 



GLUTEW (Co lie vegetale and Gluten, Fr. ; Kleber, Ger.) was first extracted by 

 Beccaria from wheat-flour, and was long regarded as a proximate principle of plants, 

 till Einhoff, Taddei, and Berzelius succeeded in showing that it may be resolved by 

 means of alcohol into three different substances : one of which resembles closely animal 

 albumen, and has been called Zymome, or vegetable albumen; another has been 

 called Gliadine ; and a third, Mucine. 



Gluten, when dried in the air or a stove, diminishes greatly in size, becomes hard, 

 brittle, glistening, and of a deep yellow colour. It is insoluble in ether, fat and 

 essential oils, and nearly so in water. Alcohol and acetic acid cause gluten to swell 

 and make a sort of milky solution. Dilute acids and alkaline lyes dissolve gluten. 

 Its constituents are not precisely determined, but nitrogen is one of them, and accord- 

 ingly when moist gluten is left to ferment, it exhales the smell of old cheese. 



Some years since, M. E. M. Martin, of Vervins, proposed to extract the starch 

 without injuring the gluten, which then becomes available for alimentary purposes. 

 His process is a mechanical one (resembling that long practised in laboratories for 

 procuring gluten), and consists in washing wheat-flour, made into a paste, with water, 

 either by the hand or machinery. 



The gluten thus obtained is susceptible of numerous useful applications for alimen- 

 tary purposes. Mixed with wheat-flour, in the proportions of 30 parts of flour, 10 of 

 fresh gluten, and 7 of water, it has been employed to produce a superior sort of maca- 

 roni, vermicelli, and other kinds of Italian pastes ; and MM. Veron Freres, of Paris, 

 have made with it a new sort of paste, which they have termed granulated gluten 

 (gluten granule). 



GLYCERINE is a sweet substance extracted from fatty substances. It may be 

 prepared in the utmost purity by the following process : 'If we take equal parts of 

 olive-oil and finely-ground litharge, put them into a basin with a little water, set this 

 on a sand-bath moderately heated, and stir the mixture constantly, with the occasional 

 addition of hot water to replace what is lost by evaporation, we shall obtain, in a short 

 time, a soap or plaster of lead. If, after having added more water to this, we remove 

 the vessel from the fire, decant the liquor, filter it, pass sulphuretted hydrogen through 

 it to separate the lead, then filter afresh, and concentrate the liquor as much as pos- 

 sible without burning, upon the sand-bath, we obtain glycerine ; but what remains 

 must be finally evaporated within the receiver of the air-pump. Glycerine thus pre- 

 pared is a transparent liquid, without colour or smell, and of a syrupy consistence. It 

 has a very sweet taste. It specific gravity is 1'27 at the temperature of 60. When 

 thrown upon burning coals, it takes fire and burns like an oil. Water combines with 

 it in almost all proportions ; alcohol dissolves it readily ; nitric acid converts it into 

 oxalic acid ; and, according to Vogel, sulphuric acid transforms it into sugar, in the 

 same way as it does starch. By yeast it becomes acid by the formation of formic and 

 metacetic acids.' 



Its constituents are, carbon 40, hydrogen 9, oxygen 51, in 100. 



Glycerine is one of the products of the saponification of fat-oils. It is produced in 

 large quantities in the soap-manufactories in a very impure state, being contaminated 

 with saline and empyreumatic matters, and having a very strong disagreeable odour. 

 In order to obtain glycerine from this source, the residuary liquors are evaporated and 

 treated with alcohol, which dissolves out the glycerine. The alcohol having been 

 separated by evaporation, the glycerine is diluted with water, and boiled with animal 

 charcoal. This process must be repeated several times, or until the result is sufficiently 

 free from smell. It is, however, difficult to obtain pure glycerine from this source, on 

 account of the nature and condition of the ingredients usually employed in making 

 soap, which it is almost impossible to deprive of rancid odour. 



The compounds of glycerine with the fatty acids constitute the various kind of fata 

 and oils, but the base does not appear to have the same composition in all. A certain 

 quantity of water appears to separate, and the equivalent of glycerine to be in somo 

 fats, but half what it is in others. 



Glycerine is now obtained in groat quantities from palm-oil, in the process of puri- 

 fication for candles. It is employed with much advantage to preserve soft-bodied 

 animals. It is manufactured into soap, is administered internally, and is supposed to 

 possess highly nutritive properties. It has been employed in cases of deafness, and in 

 diseases of the throat. By somo it is used to preserve collodion plates in a state of 

 sensitiveness for many days. 



