or ELABORATORY, the chemist's workhouse, or the place where furnaces are built, vessels kept, and operations are performed. In general the term laboratory is applied to any place where physical experiments in pharmacy, chemistry, pyrotechny, &c., are performed.

As laboratories must be of very different kinds, according to the nature of the operations to be performed in them, it is impossible that any directions can be given which will answer for everyone. Where the purposes are merely experimental, a single furnace or two of the portable kind will be sufficient. It is scarcely needful to add, that shelves are necessary for holding vessels with the products of the different operations; Laboratory, and that it is absolutely necessary to avoid confusion and disorder, as by these means the products of the operations might be lost or mistaken for one another. Mortars, filters, levigating stones, &c., must also be procured; but from a knowledge of the methods of performing the different chemical operations will easily be derived the knowledge of a proper place and proper apparatus; for which see Chemistry, and Furnace.

Moreau has contrived a portable laboratory with which many chemical experiments may be conveniently performed. The following is a description of it.

Fig. 1 represents the whole apparatus ready mounted Plate for distillation, with the tube of safety and a pneumatic receiver. A is the body or reservoir of Argand's lamp, with its shade and glass chimney. The lamp may be raised or lowered at pleasure by means of the thumb-screw B, and the wick rises and falls by the motion of the small-toothed wheel placed over the waste cup. This construction is most convenient, because it affords the facility of altering the position of the flame with regard to the vessels, which remain fixed; and the troublesome management of bended wires above the flame for the support of the vessels is avoided, at the same time that the flame itself can be brought nearer to the matter on which it is intended to act. D, a support consisting of a round stem of brass, formed of two pieces which screw together at about two-thirds of its height. Upon this the circular ring E, the arm F, and the nut G slide, and are fixable each by its respective thumb-screw. The arm carries a moveable piece H, which serves to suspend the vessels in a convenient situation, or to secure their position. The whole support is attached to the square iron stem of the lamp by a piece of hard wood I, which may be fixed at any required situation by its screw. K represents a stand for the receivers. Its moveable tablet L is fixed at any required elevation by the wooden screw M. The piece which forms the foot of this stand is fixed on the board N; but its relative position with regard to the lamp may be changed by sliding the foot of the latter between the pieces OO. P, another stand for the pneumatic trough. It is raised or lowered, and fixed to its place, by a strong wooden screw Q. R is a tube of safety, or reversed syphon, which serves, in a great measure, to prevent the bad effects of having the vessels either perfectly closed, or perfectly open. Suppose the upper bell-shaped vessel to be nearly of the same magnitude as the bulb at the lower end of the tube, and that a quantity of water, or other suitable fluid, somewhat less than the contents of that vessel, be poured into the apparatus: In this situation, if the elasticity of the contents of the vessel be less than that of the external air, the fluid will descend in the bulb, and atmospheric air will follow and pass through the fluid into the vessels; but, on the contrary, if the elasticity of the contents be greater, the fluid will be either retained in the tube, or driven into the bell-shaped vessel; and if the force be strong enough, the gaseous matter will pass through the fluid, and in part escape.

Fig. 2. Shews the lamp furnace disposed to produce the saline fusion; the chimney of glass shortened; the support D turned down; the capsule of platina or silver S placed on the ring very near the flame. Fig. 3. The same part of the apparatus, in which, instead of the capsule, a very thin and small crucible of platina T is substituted, and rests upon a triangle of iron wire placed on the ring.

Fig. 4. Exhibits the plan of fig. 3.

in military affairs, signifies that place where all sorts of fire-works are prepared, both for actual service and for experiments, viz. quick matches, fuzes, port-fires, grape-shot, case-shot, carcasses, hand-grenades, cartridges, shells filled, and fuzes fixed, wads, &c. &c.