DIVISION, in general, is the separating a thing into two or more parts.

Mechanical Division signifies that separation which is occasioned in the parts of a body by help of mechanical instruments. The mechanical division of bodies does indeed separate them into smaller, homogeneous, and similar parts; but this separation cannot extend to the primary integrant molecules of any body, and consequently it is incapable of breaking what is properly called their aggregation ; also, no union is formed betwixt the divided and dividing bodies, in which respect division essentially differs from dissolution.

Division is not properly a chemical operation; it is, in fact, only employed preparatorily, in order to facilitate other operations, and particularly solution. For this purpose it is very useful, as it increases the quantity of surface, and consequently the points of contact, of any body. Different methods are used to divide bodies according to their nature. Those which are tenacious and elastic, as horns and gums, require to be cut, rasped, or filed. Metals, because of their ductility, require the same treatment; but as they are also fusible, they may be quickly and conveniently reduced into grains small enough for most operations, by pouring them, when melted, into water. All brittle bodies may be conveniently reduced into fine parts by being bruised in a mortar with a pestle. Very hard bodies, such as glass, crystals, and stones, particularly those of the vitrifiable kind, before they are pounded, ought to be plunged when red hot into water, by which means they are split and cracked, and rendered more easily pulverable. Bodies of this kind may also be bruised or ground by means of a hard and flat stone, upon which the matter is to be put, and bruised by another hard stone so small as to be held and moved upon the larger stone with the hand. The larger stone is called a porphyry, from its being generally of that kind of stone; and the operation is called porphy-rization. Instead of porphyrization, a mill may be used, composed of a hard grit millstone, moving round upon another stone of the same kind, which must be fixed; in the upper stone is a groove or channel through which the matter to be ground passes. By this method a substance may be more quickly reduced to a fine powder than by porphyrization. But these mills can be only employed for considerable quantities of matter.

These methods of mechanically dividing bodies are attended with some practical inconveniences, the most considerable of which is, that some parts of the dividing instruments are always struck off and mixed with the matter to be divided. This may greatly affect the operations; for instruments of iron and copper furnish metallic colouring particles, and copper is very prejudicial to health. Porphyry is coloured by a reddish-brown matter, which injures the colour of crystal glasses, enamels, and porcelains made with matters ground upon this stone. These matters, therefore, must be cleansed after their porphyrization, or else no instruments capable of injuring the intended operations ought to be employed. Thus, for the preparation of all medicines to be taken internally, no copper instruments, as mortars, pestles, or the like, slwuld be used, those made of iron being preferable; and mortars, grinding stones, and mill-stones, made of hard and white stones, ought to be employed, instead of those made of porphyry, for substances which are to enter into the composition of enamels, crystal glass, and porcelain, the whiteness of which is a most necessary quality.

Division, in Algebra. See Algebra. Division, in Arithmetic. See Arithmetic. Division of an Army, in the military art, two or more brigades under the command of a general of division.

Division, in sea affairs, a number of ships in a fleet or squadron of men of war, distinguished by a particular flag or pendant, and usually commanded by a general officer. A squadron is commonly ranged into three divisions, the commanding officer of which is always stationed in the centre.