An All-Glass Still with Automatic Float Feed GEORGE F. LIEBIG, JR. University of California Citrus Experiment Station, Riverside, Calif. The still consists of a %liter round-bottomed Pyrex glass flask, A, with a side arm sealed to n 38 X 200 mm. Pyrex test tube, B. The sidearm opening on B must be a t a lower level than that on A to prevent the flow of hot liquid from A back into B. The liquid level xvithin A is maintained by float C which consists of a 26-mm. Pyrex test tube sealed off and joined t o a solid glass rod, the end of which is slightly tapered and ground to form a tight seal a t the constriction, D , in the glass tubing leading from the supply reservoir. A glass bottle, E , with the bottom cut off provides a cover for the top of tube B. By raising or lowering the float-ground-glass valve assembly, the liquid in A is adjusted to the desired level. The neck of A is reduced in diameter and connected by a piece of glass tubing 14 mm. in diameter to a $ 2 4 / 1 ~ groundglass joint lvhich joins the still t o a conall beads in A aid in
RESERVOIR
Using a Cenco 500-watt giant electric heater, this still will produce about 500 ml. of redistilled water per hour. A still as described has been operated continuously for long periods in the author’s laboratory v-ithout attention other t h a n for periodic renewal of Tmter in the supply reservoir and removal of the redistilled water. At periodic intervals the still is dismantled and cleaned. This still is suitable for redistilling other liquids as well. For liquids more volatile than water, a cooling jacket could he applied to tube B if necessary.
HE need for considerable quantities of redistilled water in connection with plant nutritional studies led t o the construction of a simple all-glass still with an automatic float feed. With large supply and receiving reservoirs, con-
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tinuous operation over long periods is possible.
Magnetic Shaking Device S. KIYOMIZU, University of Washington, Seattle, Wash. Each flask is held rigidly on the platform by means of a rubber band, 14, stretched around three machine bolts, 15, coming up through the platform as shown.
A
MAGKETIC device has been found very satisfactory for shaking samples in a thermostat.
The agitator holds six 250-cc. glass-stoppered Erlenmeyer flasks on a swinging platform, 1, supported from a wooden frame, 2, which is placed across the top of the thermostat, immersing the flasks in the liquid of the thermostat. The platform is supported on the left side by two metal strips, 3, with movable connections, 4, t o the frame and latform, and on the right side by one metafstrip, 5, connected to the middle by a movable connection, 6. This strip pivots a t 7 on a metal piece, 8, rigidly attached to the frame, and is guided on the upper end by a forked guide, 9. The platform is driven by means of a soft iron rod, 10, which is pulled into the coil of the electromagnet, 11, as the current is turned on, moving the platform to the left. As the current is interrupted, the spring a t 12 pulls the strip in the opposite direction, causing the iron rod to emerge from the coil and the platform to return to its original position. The process repeats when contact is again made. A direct current of 50 volts is used in the coil, and is alternately broken and connected by an electric flasher button inserted under the fuse in the light base, 13. The speed of movement may be controlled by the type of flasher button used. 174
