ANALYTICAL .CHEMISTRY
944
pressed air. The operator then grasps the device, holding one fineer nartiallv on Dort 17. to Drovide Dositivelv controlled at&aation. "h%en*his finger is a N q from the port, the Sjr supply will be diverted through conduit 16, as it is large in diameter in relation to nozzle 15 and no atomization will take place. When the operator's finger is pressed againinst port 17, the air
Figore 1
14
Figure 1
upward movement of the platform limited by a lip on the ramp, which projected approximately inch ove? the platform. The turntable N= rotated by a weighted cord, wrapped around an 11-inch wooden drum attached concentrically to the upper disk. This cord Dassed over a smooth elass rod to the weieht. freely suspended below the level of the cable top, The gen&l
were sunported bv their hms in the UDp& disk, were c&ed up t,he rani$, B. The balance ann, C %th attached platform D and pin E, was in the horieont,al pAsition, and tube F NZS delivered to the platform while the tube ahead, G, bore against E. loekine the turntsble'in Dosition. As F N ~ filled. B the increase i n weinhtlbecame suffieient'to lower the balance ai-&, thus hrinp2 Figure 2
liquid i8 used, air can enter the bottld via. opening 7, 'annular passage 18, and vent 9. The atomizer can also be used in an open vessel or test tube Automatic Receiver Changer. E. S. Sanderson, Division of Industrial and Cellulose Chemistry, MoGill University, and Pulp and Paper Research Institute of Canada, Montreal, P. Q., Canada. course of a recent investigation, i t became necessary Iarateto use a chromatographic column of powdered cellulose to s e p several grams of complex mixture of simple reducing N THE
a
sugars. Although commercial receiver changers are available, they are comparatively expensive; the photoelectric instrument designed by Stein and Moore (3) and the electrically timed apparatus of Hough, Jones, and Wadman ( 1 ) require special skills in construction, and the design of Phillips (8) requires a large water bath. The mechanical changer described, actuated by the weight of the sitmple collected, N&B easily constructed in the laboratory workshop, and was capable of operating continuously and with little attention for a t least 120 hours. During this time five hundred to six hundred 5- to I-ml. samples of effluent could be collected. A turntable. consisting of two oarallel aluminum disks, 34 inches in diamktor and heid 3.5 inches apart by lengths of aluminum tubing, N ~ Ssupported by a vertical d e , fitted with ball hemines. Fln,eh disk NRS nierced with 98 holes. evenlv snaced around the periphery. aluminum ramp, 7' inches ling, 2 inches wide. 1.75 inches hiEh at the lower end, and 3.25 inches high at thd upper end, w&s ositianed directly below, and in line with the holes. A l2-incg bdmce arm, made of aluminum t,nhine. was k m t in nlace bv two steel ball bearines between the cunncd ends a ah& and"tw0 sdiustina screws,-mounted on a ~~~~~~
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For maximum precision, the ramp, platform, ana brass pin NBS just sufficient to operate the turntable, and tubes with deformed bases, or those greatly aver- or underweight, were notused. Variations in the volumes of samples collected were seldom more than 2 to 3 ml. if these precautions were observed. A sliding weight on the remote end of the volume of sample desii were waxed and polished, the weight on the cord
The assistance of W. H. de Montmorency, who supervised the construction of the a],paratus, the interest shown by C. B. Purves, and the fellow ahip awarded by the National Research Council of Canada are gratefully acknowledged. LITERATURE CITED
(I) Hough, H., Jones, J. K. N., and Wadman, W. H., J . Chem. Soc., 1949, 2511. (2) Phillips, D. M. P., Natwe, 164, 544 (1949). (3) Stein, W. H., and hloore, 5.. J . Biol. Chem., 176, 337 (1948).
