732 RESINS SYRUPS 



in water, soluble in spirit, and melt when heated. They 

 dissolve in alkalies, forming soaps. They are frequently 

 found in plants conjoined with volatile oil, constituting an 

 oleo-resin, such as that of copaiba or of cubebs. Occasion- 

 ally they are associated with gum, as in the gum-resins, 

 asafostida, ammoniacum, myrrh, and gamboge. The resins 

 proper are only sparingly soluble in the animal secretions, 

 but they irritate by contact, and hence, when swallowed, 

 are cathartic and diuretic. The oleo-resins are more active ; 

 they stimulate mucous surfaces, from which they are ab- 

 sorbed or excreted. Gums or exudations from the stems of 

 plants contain arabin or soluble gum (acacia), bassorin or 

 less soluble gum, and cerasin or insoluble gum. Alcohol 

 precipitates solution of gum. 



SYRUPS-CONFECTIONS-ELECTUARIES 



Syrups are saccharine solutions, usually containing 

 flavouring or medicinal substances. Their specific gravity 

 ranges from 1*300 and 1*400. Their consistence is im- 

 portant. If too thin and weak, they become mouldy, and 

 are apt to ferment ; if too thick and strong, the sugar 

 crystallises out. But the B.P. ensures uniformity and good 

 keeping by definite instructions as to the proportion of 

 refined sugar and other constituents in the twenty-two syrups . 

 Simple syrup is prepared by dissolving, by the aid of heat, 

 five pounds of refined sugar in two pints of distilled water, 

 and adding sufficient water to make 7J Ibs. of syrup. The 

 syrups chiefly used in veterinary practice are those of 

 buckthorn, squill, rhubarb, chloral, ginger, and iron iodide, 

 in which the sugar prevents oxidation. Electuaries are 

 made with sugar, mucilage, honey, or treacle. Confections 

 or conserves are soft pastes, largely composed of sugar or 

 honey, and, like syrups and electuaries, are chiefly used as 

 vehicles for administering powders, or disagreeably tasted 

 drugs. 



TINCTURES-SPIRITS-WINES 



Tinctures are spirituous solutions of active principles. 

 The usual solvent is ethylic alcohol (45 to 90 per cent.). 



