Characteristics of Stationary Mercury Electrode PAUL V. PEURIFOY and W. G. SCHRENK Kansos Agriculturol Experiment Sfotion, Monhaftan, Kan.
0.74-em. inside diameter. A 4.5-cm. length of 3-cm.-diameter brass rod served as a hushing for the shaft. The stirrer speed was controlled by reference to a StewahWarner portable tachometer connected to the top of the stirring motor shaft by a flexible rnbher tube. The water used for all purposes was either double-distilled or distilled water passed through an ion exchange column. The tank nitrogen was passed through a trap containing an alkaline pyrogallol solution before entering the cell. All reagents were reagent grade. All polarograms were recorded on a Sargent Model XI1 polarograph and voltages mere determined with a Central Scientific Co. Model 83411 potentiometer. The resistance across the cell was measured with a Wheatstone bridge, audiogenerator, and oscilloscope arrangement suggested by Pesce, K n e s baeh, and Ladisch (5).
b An investigation was made of the usefulness, sensitivity, reproducibility, and characteristics of a stationary mercury electrode of small diameter which is used in conjunction with o glass tube stirrer. A modified cell design simplifies the manipulations of the electrode. The behovior of benzil, 1.3-dinitrobenzene, moleic acid, oxalic acid, bromide ion, thiosulfate ion, uranyl ion, and ions of cadmium, cobolt, copper, lead, antimony, stannous tin, and thallium wos determined. Some success was achieved in eliminoting anomalous peaks. Half-wave potentiols ond diffusion currents were reported. The lower limit of concentration wos about 0.5 X lO-%4. A precision within about 0.4Ya was observed in some cases. The half-wave potentials determined with this electrode were generally 'more negative than the corresponding potentials obtained with the dropping mercury electrode. The diffusion currents were two to four times greater than those obtained with the dropping mercury electrode.
PROCEDURE
Figure 1. Exploded view of stationary mercury electrode cell 1. 2.
3. 4.
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of the recent innovations in polarography involves the use of a stationary mercury electrode of small diameter employing controlled stirring, which was reported by Arthur and associates (f). The polarographic waves obtained with such an electrode are usually smooth and maxima are frequently absent where they would he observed with the dropping mercury electrode. Marple and Rogers (3) determined trace amounti; of lead using a mercuryplated platinum electrode which was stirred with a glass tube. The waves obtained were very uneven. Rosie and Cooke (6) used a 3-sq. cm. mercury pool with stirred solutions to increase greatly the sensitivity of the polarographic method. This investigation is concerned with the general behavior of the electrode arrangement reported by Brthur and associates (1). NE
APPARATUS AND MATERIALS
The electrolysis cell used in this work vas similar to the one described by
Brthur and associates (f), except for a few modifications. An exploded picture of the cell is shown in Figure 1. 410
ANALYTICAL CHEMISTRY
5.
Body of cell Boll and rocket clamp Reference electrode cell Spe
