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V O L U M E 26, NO. 9, S E P T E M B E R 1 9 5 4 A pressure regulator has been described by Furter and Steyermark [ANAL.CHEM.,20, 257 (1948)] in which a 570 solution of sodium hydroxide is used. The apparatus utilizes a leveling bulb for adjusting the pressure, thereby preventing the use of certain liquids such as sulfuric acid. The apparatus described here is essentially R modification of Steyermark and Furter’p regulator in which the leveling bulb has been replaced by a closed chamber in which the air pressure can be varied. The resulting gas pressure regulator is a onepiece all-glass apparatus (Figure 1) permitting the use of concaentrated sulfuric acid or other corrosive liquids without contamination. As there are no moving parts, this regulator can be permanently mounted in a rigid all-glass system. The pressure iw&tor consists of three concentric tubes, A , B , and C: and ~ c s e r v o i iD~ . The pressure gradient is adjusted by pumping air into rcsrrvoir n. This forcw the liquid u p into the tubes.
too low for the tube to ionize, and the relay coil is not energized. When the contacts open, the voltage increases and causes a primary discharge, which starts current flowing to the anode. Thia current energizes the relay coil and switches power from onc outlet socket to the other. 039M J Y)
z a Iw
IO
I 0
‘b-..%LJ
r 110 V A C
Figure 1. Circuit of Cold-Cathode Relay Figure 1. All-Glass Pressiire Regulator
4-mf. 150-volt electrolytic condenser .V. N E 4 1 neon lamp C.
R. 2500-ohm 10-ma. relay Outlet socket Isolation transformer V. OA4G or IC21 tube M . Megohm
S. 2‘.
The gas is turned 011 through inlet tube 9. The diff’erence in the height of the liquid in tubes C and B determines the pressure in the outlet tube, B. The pressure range desired \Till govern the over-all height of the apparatus. The excess gas escapes through the trap a t the top of tube C. A three-way stopcock. F , is used for maintaining or releasing pressure on reservoir D. Several of these regulators have been used very successfully for over a year on microconibustion apparatus vithout discoloring the sulfuric acid
Cold-Cathode Electronic Relay. Frank A. Leisey. Research Department, Standard Oil Co. (Indiana), Khiting, Ind. LECTROSIC
relays are useful for the control of temperaturc,
E pressure, and liquid level, and in other applications in the
laboratory. Cold-cathode tubes are especially convenient in relay circuits because they have no filament, operate instantly n-hen energized, require zero standby poner, and have long life. A cold-cathode relay, n-hich is an improved version of that deEXG.CHEX, ASAL. ED., Ecribed by Rudy and Fugassi [IND. 12, 757 (1940)], has been devised and successfully u v d in these laboratories. The relay operates directly on 110-volt alternating current. T h e circuit, shown in Figure 1, consists of a cold-cathode tube operating a single-pole double-throw relay. Resistors in the contact leads limit the control current to less than 200 pa. -4 small line transformer provides electrical isolation from the power lines. I n applications where the control contacts are well insulated from ground, this transformer may be omitted. A novel piloblight hookup uses a small neon lamp in which one electrode glows continuously and the other glows only Jvhen the relay coil is de-energized. Operation of the relay depends upon the opening or closing of contacts of a control device, such as a thermoregulator, manometer, 01 float. When these contacts, connected between terminals 1 and 2, are closed, the voltage of the starting electrode is
This circuit is particularly useful when the contacts are closed most of the time. When the contacts are normally open, they should be inserted between terminals 2 and 3. This change reverses the operation of ths circuit and gives longer tube life. Either an OA4G or a 1C21 tub8 may be used; the former is preferred because it will operate the relay over a wide1 range of line voltage. The relay parts are inexpensive and can be mounted in a small housing.
Apparatus for Automatically Scanning Two-Dimensional Paper Chromatograms for Radioactivity. W. J. Wingo, Biochemistry Department, The Cniversity of Tevas 11.D. -4nderson Hospital for Cancer Research, Houston, Tes. 7 E V E R ~ Ldevices
for automstically scanning paper chromato-
3 grams for the detection of radioactive spots have been described (1-6’). Each consists of a mechanism for moving a paper strip past a collimating slit in front of a Geiger counter or ion chamber and an apparatus for recording the counting rate as a function of the position of the paper. These devices are limited to use with one-dimensional chromatograms; an apparatus to scan two-dimensional chromatograms for radioactivity should have many additional advantages. The design and construction of such an apparatus are shown in Figure 1. The chromatogram is held by means of Scotch tape to one end of the cylinder, 8 . Around the other end of A is wrapped the paper for the recording. A is 20 inches long and 4 inches in diameter; chromatograms as large as 10 X 12 inches can be scanned. B is a rod which for half its length is threaded with a four-turns-per-inch square thread. The ends of A are plugged with disks. The disk in the right end as shown in Figure 1 is bored to let the unthreaded portion of B pass with a loose sliding fit. The left plug carries in its center an aluminum insert threaded to match the threaded part of B; i t is also drilled with two holes for rods C and C’. These are attached to disk D , which is driven by synchronous motor E a t 6 revolutions per hour. The end of B is recessed and fits loosely over the end of the motor shaft a t F . -4s D turns, rods C and C‘ cause A to rotate and to move toward the motor along B. An end-window Geiger tube and preamplifier, G, are housed in the lead pig, H . The end of the Geiger tube is covered by an aluminum cap, in the center of which is milled a slot I/, inch wide and inch high. This slot is positioned a t the same level as the center of cylinder A and is less than 1 mm. from the paper; as the drum is moved
