V O L U M E 2 8 , NO. 2, F E B R U A R Y 1 9 5 6 designed separatory funnel is filled with a predetermined volume of solution, and supported so the outlet tips provide the desired liquid level in an evaporating dish when the stopcock is opened. (The side-arm level-regulator is not filled a t the start t o the same level as the liquid in the flask; however, the liquid levels are automatically equalized after evaporation commences.) The device is easily held by a Cinch ring support from which a 1-inch section has been removed. The feeder operates without attention until the evaporation is complete. The offset design permits the use of infrared lamps over the dish. With such lamps and dish holders fabricated from carbon block [Susano, C. D., ANAL. CHEXI.27, 1038 (1955)], very rapid evaporations can be made with little effort.
28 1
Table I.
Performance Dataa
Thermometers", d Standard b I I1 I11 42.0- 4 3 . 5 43.5- 44.0 43.0- 44.0 42.0- 43.0 79.5- 8 1 . 0 80.0- 8 1 . 0 81.0- 8 2 . 0 81.5- 8 2 . 0 134.0-135.5 136.0-137.0 136.0-137.0 135.8-136.3 147.5-148.5 148.0-149 0 150.0-151.0 149.5-150.0 174.0-174.5 173.5-174.5 174.5-177.0 174.0-175.0 215.5-216.5 214.0-215.5 216.0-217.0 215.0-216.0 243.5-244.0 243.0-244.0 244.0-246 5 242.0-244.0 305.5-306.0 304.5-306.5 305.5-306.5 305.0-306.0 Readings are at heating rates of 2' C. per minute. b Temperature at which crystal and liquid are in equilibrium (not whole range for complete melting). C Ordinary 3-inch yellow-back thermometers. d Columns I and I1 represent performance on same block; column I11 is for a different block.
ACKNOWLEDGMENT
The problem and original approach were suggested t o the author by L. E. Owen, Laboratory Division, Goodyear Atomic Corp., Portsmouth, Ohio.
Aluminum Melting Point Block F. F.
Anderson, Research Department, Ciba Pharmaceutical Products, Inc., Summit, N. J.
o
the past several years, the organic chemists i n these research laboratories have found the aluminum melting point block most convenient for routine measurement of melting points. VER
i'
20,
I
I
IO
20
30
40
50
60
TIME IN MINUTES
Figure 2.
Figure 1. Aluminum melting block 1. 2. 3. 4. 5.
Heaters, 2.5 X 31s inch, 75 watts
Calibration of melting point apparatus
Figure 1 shows the construction of the block. Three holes for capillaries and one thermometer hole can be seen a t the top. The lens is mounted on the side for observation. Three 75-watt Chromolox heaters, controlled by the attached variable voltage transformer (Powerstat), are inserted from the bottom. Light from a 6-watt lamp in the hollow base passes through a borosilicate glass rod to the sample chamber. A compressed air hose may be connected to the tube a t the bottom for rapid cooling of the block after a reading has been taken. Calibration curves for the apparatus are shown in Figure 2.
T,irht 6 watts
6.
7. 8.
Air outlet, 3/1a-inch diameter 9. Support, */a X 8 inches 10. Aluminum block, 2 X 3/76 inches 11. Aluminum cup, 2 inches at top, 7s,' inch at bottom 12. Brass eyepiece, 0.75 X 0.5 X 1.5 inches
Improved Migration Cell E. R. Nightingale, Jr., Department of Chemistry and Chemical Engineering, University of Nebraska, Lincoln 8, Neb.
method for determining whether ionic aggregates A in solution are positively or negatively charged is to observe SIMPLE
The design of the block has slowly changed as new features were incorporated. The apparatus described has been found to be most useful, permitting melting points to be measured with an ordinary yellow-back immersion thermometer, from room temperature to over 300' C., with an accuracy of about 1' C. (Table
I).
the direction of migration of the species in an electric field. While a simple U-tube may serve adequately, it is desirable to use a cell in which the test solution and electrolyte are not subject to mixing and which is rapidly and conveniently filled and emptied. Figure 1 shows a cell designed to fulfill these requirements.
