GRANIL′LA. A small inferior variety of cochineal (which see).
GRANULA′TION. The act or process of forming, or breaking into, grains or small masses.
The granulation of MEDICINES has of late years received considerable attention from both foreign and British pharmaceutists. In France, granulated powders (POUDRES GRANULÉES) are coming into general use in place of impalpable powders, the most unpleasant of all forms of medicine. The French process consists in enveloping the particles of medicines in syrup by means of heat and constant stirring. Mr Banner, of Liverpool, has lately introduced a method of granulating medicines far preferable to that of the French pharmaceutists. The powder to be granulated is placed in a mortar, and mucilage of gum acacia is gradually added until a crumbly mass is made; this is then rubbed through a wire sieve (about 12 meshes to the inch), and the granules produced are spread out on paper, and left to dry spontaneously, or they are placed in a copper pan, and kept in constant motion over a stove until dry; when perfectly dry, they are placed in a mortar, and sufficient quantity of strong tincture of tolu (3 dr. to 1 oz.) is added to them, until by constant stirring they all appear glossy and shining; they are then dried again by a gentle heat, being kept in constant motion. The granules thus formed keep well, are tasteless, and are much more elegant and agreeable preparations than pills or ordinary powders. Many saline substances are granulated by the simple process of dissolving the salt in water, and evaporating to dryness with constant stirring.
Metals are granulated (reduced to drops, grains, or coarse powder) by pouring them, in the melted state, into water. In many cases they are allowed to run through the holes of a species of colander or sieve to produce minute division; and in order to render the drops spherical, they are allowed to fall from a sufficient height to permit of their acquiring the solid state before striking the water. Lead shot is made in this way. Shot towers are often upwards of 100 feet in height. See Copper, Gunpowder, Powder, Zinc, &c.
GRAPES. Syn. Uvæ, L. The fruit of Vitis vinifera, or the common grape vine. Ripe grapes are cooling and antiseptic, and in large quantities diuretic and laxative. They are very useful in bilious affections and dyspepsia, and in all febrile, putrid, and inflammatory complaints. The skin and seed, which are indigestible, should be rejected. “Grapes which contain a large quantity of sugar are, if taken without the husks, the safest and most nutritive of summer fruits.” (Cullen.) “The subjects of pulmonary affections, who pass the summer in Switzerland, may try the effects of a course of grapes, ‘cure de raisins,’ a remedy held in high estimation in several parts of the Continent.” (Sir J. Clark.)
Grapes, in bunches are preserved by wrapping them in silver paper, and packing them in dry bran. Each bunch is suspended by the stem with the fingers of one hand, whilst the bran is poured round it with the other; the jar being occasionally gently shaken as the process of packing proceeds. Some paper is then laid over the top of the jar, the mouth or cover of which is, lastly, tied firmly over with bladder, to exclude the air and moisture. See Fruit, &c.
GRAPH′ITE. See Plumbago.
GRATE. A frame of iron bars used for burning coal as fuel. In the construction of a grate it is desirable to make the perpendicular height of the fuel as great as is consistent
with safety. A stratum of burning coal will radiate considerably more heat into an apartment if placed vertically than if arranged horizontally; besides which a great saving of fuel will be effected in proportion to the heat radiated. Hence the faulty construction of the old-fashioned wide grates. The fuel should also be so divided in a fireplace as to be easy of ignition, and so placed as to give free access of air to all its parts, as the smoke is then more likely to be burnt.
GRAV′EL. A collection of small pebbles commonly mixed with sand or clay, or both. Gravel for garden walks is chosen for its fine colour and binding properties. The gravel of Kensington and Wimbledon is esteemed the finest in the world. Gravel walks when once in order, may be rendered nearly equal to asphalt by pouring over them tar or a mixture of tar and pitch, absorption being promoted, if required, by the application of a hot iron.