| 摘要 |
662,802. Electrolytic cells for measurement of electro - chemical properties. NATIONAL RESEARCH DEVELOPMENT CORPORATION. May 27, 1949, No. 14306/49. Class 37. In apparatus for determining electro-chemical potentials, for example pH or polarographic apparatus, the liquid junction connecting two half cells or electrode vessels is disposed within a thermostatic bath or zone and the controls such as taps and liquid levelling devices are situated outside said bath or zone. In Fig. 1, the liquid junction is formed in wide bore limb 12 of an inverted U-tube and connects a calomel electrode 1 with a second electrode (not shown) to constitute a cell immersed in a thermostatic bath. Fig. 2 shows a polarographic cell comprising a liquid junction, as Fig. 1, in conj unction with a calomel electrode and mercury dropping electrode and immersed in a thermostatic bath 31. KCl solution from the delivery funnel is permitted to flow and bulb 3 subsequently pressed to produce a level of liquid just below the bend in tube 12, as shown. Air is removed from the dropping electrode vessel 29 and connecting tubes by passing nitrogen through tap 20 and out through taps 6, 13 and 18. The test solution is placed in the delivery funnel 17 and de-oxygenated by passing nitrogen through the empty vessel 29. The latter is then allowed to fill by turning tap 20 to atmosphere; tap 20 is then closed. With test solution delivery tap 18 still open, tap 6 is cautiously opened and the electrolyte allowed to pass along tube 11 and around the U-tube bend and flow gently on top of the KCl solution thus forming the liquid junction; tap 6 is then closed. A relatively narrow liquid junction tube (e.g. semi-capillary bore) may be used instead of the wide bore tube shown. Fig. 2 is an all-glass form of polarographic cell with the dropping mercury capillary 27 fused-in. The electrode vessels and the liquid junction tube may be contained in separate thermostat baths. The procedure for emptying and washing the cell is outlined. Specification 661,689 is referred to. |
