Landolt cell

The Landolt cell (Figure 5.27) provides controlled convection conditions by the rotating cylinder electrode. A cylindrical shield surrounds a rotating cylinder, preventing direct current flux between rotating cylinder and counter electrode. The enforced longer way of the current lines simulates the variation of current density in a conventional Hull cell. 

In writing the Etudes de dynamique chimique (1884), van t Hoff drew on Helmholtz s 1882 paper but especially on the work of August Horstmann, a student of Bunsen, Clausius, and H. Landolt.59 As has often been discussed, van t Hoffs was an ambitious and original synthesis of disconnected ideas and theories about opposing forces, equilibrium, active masses, work and affinity, electromotive force, and osmotic pressure. He demonstrated that the heat of reaction is not a direct measure of affinity but that the so-called work of affinity may be calculated from vapor pressures (the affinity of a salt for its water of crystallization), osmotic pressure (affinity of a solute for a solution), or electrical work in a reversible galvanic cell (which he showed to be proportional to the electromotive force). 

In some cases, especially with almost colourless liquids, the zones of the field of vision exhibit somewhat different colours, which prevents accurate readings being obtained. This inconvenience is avoided by introducing a suitable plate of potassium bichromate into the eye-piece or by interposing between the lamp and the saccharimeter a glass cell with parallel faces (Landolt s so-called ray-filter) containing an aqueous solution of this salt1 by this means the more refractive rays are absorbed and the field assumes a uniform yellow tint. 

Kocan, R.M., M.L. Landolt, J. Bond and E.P. Benditt. In vitro effects of some mutagens/carcinogens on cultured fish cells. Arch. Environ. Contam. Toxicol. 10 663 -671, 1981. 

Kocan, R.M., M.L. Landolt and K.M. Sabo. Anaphase aberrations a measure of genotoxicity in mutagen treated fish cells. Environ. Mutagen. 4 181-189, 1982. 

Landolt-Bornstein, Zahlenwerte und Funktionen. Yol. 1, part 4. Berlin, Gottingen, Heidelberg Springer. 1955. Cell dimensions, structures and physical properties of many crystalline substances. 

The agreement must be regarded as extremely satisfactory, particularly as the specific heats of the two cadmium salts were only measured down to the temperature of liquid air. A more detailed discussion appears to be desirable of the question how the small temperature coefficient of the Weston cell compared with that of the Clark cell is to be explained, and how, in a more accurate calculation, account is to be taken of the heat of dilution at the cryohydric point. The cryhohydric point for the Weston cell was found to be T = 256° (cf. also my remarks (p. 118), and Landolt and BGmstein, Tabellen, p. 464, IV Aufl.). 

A very simple method to rotate an electrode is the rotation of an electrode rod or of an electrode cylinder. The calculation of the thickness of the diffusion layer is complicated but, in a first approximation, is proportional to an exponential dependence on rotation speed. An application of this method is the cell developed by Landolt for testing plating electrolytes. The standard equipment for such tests is the Hull cell (Figure 5.26). ... 

Several authors have investigated the mechanism of the deposition of these alloys. Podlaha and Landolt suggested a model of catalytic electrodeposition. The main observations of these authors concern the dependence of composition on the concentration ratio, rotation speed, and current density. A rotating Hull cell was used for the experiments, which has already been described in Chapter 5, Figure 5.27. 

The volume III/14b on structure data of sulfides, selenides and tellurides is the first part of a series of volumes which are conceived as supplement and extension to Landolt-Bomstein, New Series, Vol. III/6, Structure Data of Elements and Intermetallic Phases . They are a compilation of structure data of substances whose crystal structure was examined by means of diffraction methods (X-ray, neutron or electron diffraction) by which at least their elementary cell has been determined, or which are isotypic with substances of well known crystal structure. 

Landolt, M.L. Kocan, R.M. Fish cell cytogenetics a measme of the genotoxic effects of environmental pollutants. In Nriagu, J.R. Aquatic Toxicology. New York J. Wiley, 1983,p.336-353. 

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