Bichromate cell

Current world chlorate production (about 700 kilotons per year) is based entirely on an electrochemical method where reactions (15.21) to (15.34) occur simultanously in undivided cells. A small amount of bichromate ions are added to the solution to reduce chlorate losses by rereduction at the cathode these form a thin protective layer at the cathode which passivates the reduction of chlorate and hypochlorite ions. 

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. 

A characteristic feature of adrenal medullary chromaffin cells is the presence of numerous catecholamine storage granules ranging in size from 100 to 300 nm in diameter. These granules turn brown when exposed to potassium bichromate solutions, ammoniacal silver nitrate, or osmium tetroxide because of the oxidation and polymerization of epinephrine and norepinephrine. This process is known as the chromaffin reaction, hence the terms chromaffin cells and chromaffin granules. At least two kinds of adrenal medullary chromaffin cells have been identified in most animal species based on differences in chromaffin granules. Norepinephrine-producing chromaffin cells possess dense-... 

In order to circumvent the limited possibilities of the original Volta pile, the following period saw the development of other battery systems in which special oxidizers were introduced. In 1836, J. F. Daniell (1796-1845) developed a cell with an oxidizer in the form of copper ions in a copper sulfate solution. Cells with the use of nitric acid as oxidizer were developed in 1838 by W. R. Grove (1811-1896) and in 1841 by R. Bunsen (1811-1899). Cells containing sodium bichromate dissolved in sulfuric acid were developed in 1843 by Ch. Poggendorff (1824-1876) and in 1856 by Grenet. 

Mucous cells, found in the neck of the gland, secrete a mucus with staining properties different from those of the surface epithelium. Argentaffin cells are not seen with ordinary staining or fixation techniques. After fixation with potassium bichromate and silver or chromium impregnation, they stand out as cells scattered singly between the lining of chief cells and the basal membrane. 

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