101 



Gum-Resins. Genuine mixtures of resin, volatile oil and 

 gum; soft or hard at a mean temperature. 



Gui'jUUic Aci(l=C44 H34 Os. Forms an ingredient of the 

 gurjun-balsam or so-called wood-oil, an exudation from various 

 species of the genus Dipterocarpus, especially Dipterocarpus tur- 

 binatus, and remains together with other substances when the 

 balsam is distilled with water, while a volatile oil = €40 H32 passes 

 over. Dissolve the residue in hot patash-ley, add to the red- 

 brown solution chloride of ammonium in excess; filter and pre- 

 cipitate the liquid with hydrochloric acid. The acid subsiding in 

 dense yellow flocks, is dissolved hi ether, and yields after evapora- 

 tion of the latter, a crusty mass, which has to be recrystallised in 

 alcohol. — Forms colourless, crumbly crusts of slightly acid reac- 

 tion, fuses at 220°, boils at 260° and decomposes afterwards; is 

 insoluble in water ; dissolves difiicultly in weak, readily in strong 

 alcohol and in ether, slowly in benzol and sulphide of carbon, 

 readily in alkalies forming soaps. The salts of other bases are 

 insoluble in water. 



Guttat C40 H32, the main ingredient of gutta-percha. Dissolve 

 the gutta-percha, purified by treating with water and hydrochloric 

 acid in hot ether, press quickly the mass formed on cooling, 

 dissolve again in hot ether and wash the re-separated portion 

 with cold ether and alcohol, whereby it becomes a jelly-like mass. 

 The pressed substance is immediately to be heated to 100°, in 

 order to prevent oxydation, and is then dried. — White, fine 

 powder, when free of air bubbles heavier than water, fuses at 150° 

 to a viscid mass, and is destroyed in higher temperatures ; is 

 insoluble in alcohol and in cold ether, readily soluble in sulphide 

 of carbon and chloroform, less readily in benzol and oil of 

 turpentine. 



Glltta-Perclia, the hardened milky juice of Isonandra Gutta, 

 Sideroxylon attenuatum, Ceratophorus Leerii, Payena macro- 

 phylla, Bassia sericea, Mimusops Elengi, Mimusops Manil- 

 kara, Imbricaria coriacea, and probably other saponaceous trees. 

 Is pale-yellow, grey-white or reddish, almost as hard as wood, 

 tough and flexible at + 25°, at 48° plastic and of a doughy consis- 

 tence, consequently mollifying in hot water ; yields to water only 

 a little acid and an extractive substance, dissolves in absolute 

 alcohol partially (22%), little in cold ether, readily in warm ether, 

 sulphide of carbon, and chloroform, less readily in benzol and oil 

 of turpentine, not in acids and alkalies. Consists mainly upwards 

 to about 80°/o of a hydrocarbon (gutta), and contains besides 

 casein an oi'ganic acid, a resin soluble in ether and oil of turpen- 

 tine, another resin soluble in alcohol, and an extractive substance. 



Gyroplioric Aci(l=:LECANORic Acid. 



