G , one tip, J , of which has been drawn out and constricted. One may, if desired, cut the capillary tube at K and attach any one of
Constant Rate Feed Device. Lester G. Lundsted, Ar. hur B. .Ish, and Nathan L. Koslin (present address, Salin Laboratories, Columbus, Ohio), Wyandotte Chemical Corporation, K,vandotte, U c h . HE investigation of vapor phase reactions in the laboratory Tfrequently requires suitable means of introducing a liquid feed at low, but constant, reproducible rates in order to permit evaluation of such variables as f l o ~rate, temperature, and tube packing. A device that accomplishes this purpose and is particularly suitable for small amounts of material is described below. Previous workers have described various types of feed apparatus based on other principles [Zentner, IXD.ESG. CHEM., ANAL.ED., 16, 47 (1944), which makes use of the principle of the hlariotte bottle; Goldnasser and Taylor, J . Am. Chem. Soc., 61, 1260 (1939), which depends upon displacement of the feed liquid by mercury; and Burwell, IND. E s o . CHEM.,-4x.i~.ED., 12, 681 (1940), which depends upon gas liberated by electrolysis as the displacing medium]. Although this device is based on well known principles, it has not been described elsewhere and may prove useful to organic chemists and others confronted by small scale flow rate problems. It has been found capable of feeding a wide variety of liquids, including volatile and corrosive compounds, at f l o ~rates on the order of 0.25 to 5.0 grams per minute with a reproducibility of approximately *5Yc.
As illustrated in Figure 1, the device is made from parts available in nearly any laboratory, the other main requirement being a source of moderate gas pressure (air or nitrogen). In operation, it slow current of air or nitrogen is allowed to pass through the needle control valve, A; the pressure in the apparatus proper is read on the open-end manometer, D, and controlled by regulator B. B consists of a T-tube which can be slid up or down through one hole of a two-hole stopper fitted tightly in the mouth of a test tube containing mercury. The head of t,he T is connected to valve d and manometer D by means of rubber tubing of length sufficient to allow the tip, C, to be adjusted at any level between the bottom of the test tube and the top of the contained liquid. The manometer is connected to the liquid reservoir, F , through the three-way stopcock, E, the third arm of which is open to the atmosphere. The outlet from flask F consists of a capillary t h e ,
different tips by means of suitable flexible tubing, thus simplifying the replacement of one tip with another in order t o extend the range of flow rates. The other tip of G may be covered with glass cloth or glass wool, in order t o filter out sediment or dirt which might otherwise plug the constricted tip, J . J may serve as a drop counter; in any case, it should be above the liquid level in k' to prevent possible siphoning. If it is desired to add a fluid t o a reactor which is not transparent, a separate glass sight tube :ibove the apparatus will permit visual observation of the flow. Calitmtion of the feed system to permit adjustment to a predetermined flon. rate is accomplished by determining the weight or volume flow rates corresponding to several manometer readings. .1 plot of these flow rates rs. the corresponding manometer settings on log-log paper produces a nearly linear curve from which manometer settings to give any desired flow rate may be read.
Magnetic Distributing Adaptor for Fractional Distillation Columns. Elizabeth J. Rock and George ,J. Jane, The Cryogenic Laboratory, Periw>dvariia State College, State College, Pa.
THEmagnetic
E--
distributing adaptor described was designed to eliminate the possibility of contamination with stopcock grease in the fractionation of certain substances. Combined with a distillation column having tht. \vel1 known type of magnetic takeoff control, an all-glass s y s ten1 can be assembled in which no ground-glass joints or stopcock3 nerd be used.
The design of the adaptor is estremely simple. It consists of a flask, d.having the requisite number of take-off arms to which the receiving flasks are sealed. The distillate is conducted to thts appropriate receiver by a "magnetic policeman," D, which consists of a glass rod of proper length with an iron core sealed in as shown. It is suspended from the tip of the inlet tube by glass hook. B , which gives it freedom to swing to the side arms. The policeman is controlled b ~ . a small powerful permanent magnet, E . In practice, an llnico magnet (1 ounce in weight, and having a 6pound pull, Terrj, Sales Company, Toledo, Ohio) was found very satisfactory. The iron ring, C', around the outside of the adaptor flask provides a convenient means of holding the magnet against the flask wall, so that i t remainsin position controlling the policenian until the distillate fraction in queiL tion has been collected. TO REACTOR It has been found useful to seal a take-off arni directly below the top of the policeman when it hangs in its rest positioiii.e., no magnetic force acting. This outlet may then be used to collect the forerun in the tractional distillation.
a
VENT TO ATMOSPHERE
STOPCOCK
B D
MANOMETER
FIGURE I
(not drawn10 scale)
PRESSURE REGULATOR
626
This magnetic distributing adaptor was developed in the course of work under Contract K6 ORN-269 of the Office of Naval Research under the direction of J. G.Aston. The apparatus was constructed by Fritz lhlloy.
