. A laboratory course in plant physiology. Plant physiology; Plant ecology. APPARATUS AND MATERIALS 5* are at right angles to the support), permitting the whole arrangement to be readily moved, though in fact it generally stands on one of the apparatus tables in the laboratory. A great advantage of the saucer is that it saves any spilled mercury, and would save all in the globe if this became broken, or if the stop-cock were carelessly left open. At the same time the saucer gives room for various accessories connected with the use of mercury, includ- ing the bottle for used mercury, which shou
. A laboratory course in plant physiology. Plant physiology; Plant ecology. APPARATUS AND MATERIALS 5* are at right angles to the support), permitting the whole arrangement to be readily moved, though in fact it generally stands on one of the apparatus tables in the laboratory. A great advantage of the saucer is that it saves any spilled mercury, and would save all in the globe if this became broken, or if the stop-cock were carelessly left open. At the same time the saucer gives room for various accessories connected with the use of mercury, includ- ing the bottle for used mercury, which should never be returned to the con- tainer without cleaning. The saucer in the drawing is hollowed in the middle, but saucers can be obtained with the middle raised, in which case an opening, closed usually by a stopper, could be made at the lowest place near the mar- gin, and thus the spilled mercury could readily be drawn off. A different method of preserving mercury clean and ready for use is described by Arthur in the Botanical Gazette, 22, 1896, 471. Pressure-testing Manometer. It is often necessary to test the tight- ness of joints, stop-cocks, etc., to considerable gas-pressures, for which the arrangement figured herewith (Fig. 10) serves admirably. To the upper end of a piece of stout glass tubing, of about 5 mm. internal diameter and 75 cm. length, there is attached, by stout rubber tubing, a small funnel, while to its lower end there is attached a stop-cock joint of the kind, and bent to the form, shown by the figure. The free end of this latter piece is provided with a stout rubber tube into which may te inserted, and wired, the tube or other piece to be tested. When mercury is poured into the funnel, any desired pressure up to an atmosphere may be exerted upon the gas in the piece under test. The stop-cock permits this pressure to be released, and allows the apparatus to be drained of mercury, as may be desired. The whole arrangement is tightly wired, with rubber cushi
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