BIRD lime. The vegetable principle, to which is given the name of birdlime, was first examined by Vauquelin, who found it possessed of properties different from every other. It was found collected on the epidermis of a plant brought to Eu rope by Michaud, and called rohinia vis cose, constituting a viscid substance, which made the fingers adhere to the young twigs. From the late analysis of bird-lime by Bouillon la Grange, it is ob vious that it owes its peculiar properties to the presence of an analogous substance; which indeed constitutes the essential part of that composition. Hence the rea son of the name of bird-lime to the prin ciple itself. 1. Natural bird-lime (or that which exudes spontaneously from plants) possesses the following properties : its co lour is green ; it has no sensible taste or smell ; is extremely adhesive ; softens by the heat of the fingers, and sticks to them with great obstinacy. When heated, it melts, swells up, and burns with a consi derable flame, leaving a bulky charcoal behind it. It does not dissolve in water ; alcohol has but little action on it, especi ally when cold. By the assistance of heat it dissolves a portion of it ; but in cooling, allows the greatest part to preci pitate again. When exposed to the air, it continues glutinous, never becoming hard and brittle, like the resins. It com bines readily with oils. Ether is its true solvent, dissolving it readily without the assistance of heat. The solution is of a deep green colour. The alkalies do not combine with it ; the effect of the acids was not tried. These properties arc suf ficient to distinguish bird-lime from every other vegetable principle. 2. Artificial bird-lime is prepared from different sub stances in different countries. The ber ries of the misletoe are said to have been formerly employed. They were pound ed, boiled in water, and the hot water poured off. At present bird-lime is usu ally prepared from the middle bark of the holly. The process followed in England is as follows : the bark is boiled in water seven or eight hours, till it becomes soft. It is then laid in quantities in the earth, covered with stones, and left to ferment, or rot, for a fortnight or three weeks. By this fermentation, it changes to a mu cilaginous consistency. It is then taken from the pits, pounded in mortars to a paste, and well washed with river water. Its colour is greenish, its flavour sour, and its consistence gluey, stringy, and te nacious. Its smell is similar to that of
linseed oil. When spread on a glass plate, and exposed to the air and light, it dries, becomes brown, loses its viscidity, and may be reduced to a powder ; but when water is added to it, the glutinous pro perty returns. It reddens vegetable blues. When gently heated, it melts and swells, and emits an odour like that of animal oils. When heated on red hot coals, it burns with a lively flame, and gives out a great deal of smoke, leaving a white ash, composed of carbonate of lime, alumina, iron, sulphate, and muriate of potash. Weak acids soften bird-lime, and partly dissolve it ; strong acids act with more violence. Sulphuric acid renders it black ; and when lime is added to the solution, acetic acid and ammonia separate. Nitric acid, cold, has little effect ; but when as sisted by heat, it dissolves the bird-lime ; and the solution, when evaporated, leaves behind it a hard brittle mass. By treat ing this mass with nitric acid, a new solu tion may be obtained, which by evapora tion, yields malic and oxalic acids, and a yellow matter which possesses several of the properties of wax. Cold muriatic acid does not act on bird-lime ; hot mu riatic acid renders it black. Bird-lime, when treated with oxymuriatic acid, be comes white, and is divided into hard, compact masses, having unaltered bird lime in their centre. This white sub stance may be pulverized ; it is insoluble in water ; does not melt when heated : and when treated with nitric acid,it nei ther becomes yellow, nor does it yield re sin. Acetic acid softens bird-lime, and dissolves a certain portion of it. The li quid acquires a yellow colour. Its taste is insipid. When carbonate of potash is dropped into this solution, no precipitate falls. By evaporation it yields a resinous. like substance. Some of the metallic ox ides are reduced when heated with bird lime. Litharge combines with it, and forms a kind of plaster. Alcohol, of the specific gravity 0.817, dissolves bird-lime at a boiling heat. On cooling, it lets fall a yellow matter, similar to wax. The fil tered liquid is bitter, nauseous, and acid. Water precipitates a substance similar to resin. Sulphuric ether dissolves bird-lime readily and in great abundance. The so lution is greenish. When mixed with wa ter, an oily substance separates, which has some resemblance to linseed oil, When evaporated. a greasy substance is obtained, having a yellow colour, and the softness of wax.