There is some variety in the cupboards and tables provided in the various laboratories, but, in general, they follow the design shown in Fig. 13. The table tops, 12 ft. long, are of clear maple in full-length pieces, ⅞ in. thick and 2⅝ in. wide, laid on edge and drilled at 18-in. intervals for bolts. These pieces are glued and drawn together by the bolts, the heads of which are countersunk. The tops, planed off, sanded, and rounded, are supported on pipe legs and frames of 1¼ by 1½-in. galvanized-iron pipe with screw flanges fitting to the floor and top. Under the tops are drawers and above them re-agent shelves. Halfway between the table top and the floor is a wire shelf of a frame-work of No. 2 wire interlaced with No. 12 weave of ⅝-in. square mesh. Certain of the tables used in the laboratory are fitted with cupboards beneath and with drawers, and, in place of re-agent stands, porcelain-lined sinks are sunk into them. These tables follow, in general style and construction, the re-agent tables. The tables used in connection with calorimeter determinations are illustrated in Fig. 14. The sinks provided throughout these laboratories are of standard porcelain enamel, rolled rim, 18 by 13 in., with enameled back, over a sink and drain board, 24 in. long on the left side, though there are variations from this type in some instances. The plumbing includes separate lines of pipe to each hood and table; one each for cold water, steam at from 5 to 10 lb. pressure, compressed air, natural gas, and, in some cases, live steam at a pressure of 60 lb. On each table is an exposed drainage system of 2½-in. galvanized-iron pipe, in the upper surface of which holes have been bored, through which the various apparatus drain by means of flexible connections of glass or rubber. These pipes and the sinks, etc., discharge into main drains, hung to the ceiling of the floor beneath. These drains are of wood, asphaltum coated, with an inside diameter ranging from 3 to 6 in., and at the proper grades to secure free discharge. These wooden drain-pipes are made in short lengths, strengthened by a spiral wrapping of metal bands, and are tested to a pressure of 40 lb. per sq. in. Angles are turned and branches connected in 4- and 6-in. square headers. [Illustration: Fig. 13. PLAN OF CONSTRUCTION DETAILS OF REAGENT TABLES BUILDING 21.] [Illustration: Fig. 14. CONSTRUCTION DETAILS OF CALORIMETER TABLES] The entire building is ventilated by a force or blower fan in the basement, and by an exhaust fan in the attic with sufficient capacity to insure complete renewal of air in each laboratory once in 20 min. The blower fan is placed in the center of the building, on the ground floor, and is 100 in. in diameter. Its capacity is about 30,000 cu. ft. of air per min., and it forces the air, through a series of pipes, into registers placed in each of the laboratories.