4 results for 1920, Doctoral

  • The solution of mercuric sulphide in hydrgen iodide and the solubility of mercuric iodide in solutions of potassium iodide

    Dixon, J. K. (1927)

    Doctoral thesis
    University of Canterbury Library

    In group II A. Analysis two methods are used to dissolve precipitated Mercury Sulphide – potassium chlorate and concentrated hydrochloric acid or aqua regia. These methods are essentially the solution of mercury sulphide by means of nascent chlorine. A third method has been described whereby mercury sulphide is dissolved in a sulphuric acid solution of potassium iodide. This mixture liberates hydrogen iodide which is the dissolving agent. From the equations [complicated equations here] is seems possible that the dissolving action is due to complex formation. It will be seen from equation (1) that the lower the concentration of the sulphideions the greater will be tendency for mercury sulphide to dissolve. This furnishes an explanation why potassium iodide alone cannot be used with same success as hydrogen iodide. With potassium iodide potassium sulphide instead of hydrogen sulphide will be formed during the solution reaction. As potassium sulphide is the salt of a strong base there will remain in solution a high concentration of sulphideions which must promote the back reaction shown in equation (1) and an equilibrium is all that can be attained. It is not possible to reduce the sulphide ion concentration by boiling as it is with hydrogen sulphide since potassium sulphide is non volatile. If the ordinary methods and this new method are compared it is seen that whereas nascent chlorine converts mercury sulphide into mercury chloride, the action of hydrogen iodide is to form a complex salt which has a very low concentration of mercury ions. It is possible therefore that this new method may not give so sensitive a test for mercury. The object of this portion of the work is to ascertain the possibility of testing for mercury in Group II analysis by using the hydrogen iodide method of dissolving the precipitated mercury sulphide and to compare the sensitivity of the test with that of the methods usually employed.

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  • On the species of Cystophora found in New Zealand, particularly in Lyttelton Harbour

    Bennett, Edward William (1921)

    Doctoral thesis
    University of Canterbury Library

    This thesis proposes to deal with certain species or the genus Cystophora, a fucoid common on many rocky coasts of Australasia. Three species (C. retroflexa, C. scalaris, C. torulosa) were collected from Lyttelton Harbour, South Island, New Zealand, (Map, Figs. 1,2.) and are discussed in some detail; they were identified with certainty only late in the year, after an extensive examination of all the available literature (which was far from complete), and of some herbarium specimens (for the most part doubtfully identified or not at all). The results however have furnished an account of all the known New Zealand species; this account, though in the main a compilation and comparison of earlier writers, is based on the very reliable works of J. Agardh and so can lay claim to accuracy. The anatomy and oecology, and in the main the general morphology, research methods, and some other parts, are based on actual work on the collected specimens of the above three species. Earlier work has been entirely descriptive of the morphology.

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  • The solution of mercuric sulphide in hydrgen iodide and the solubility of mercuric iodide in solutions of potassium iodide

    Dixon, J. K. (1927)

    Doctoral thesis
    University of Canterbury Library

    In group II A. Analysis two methods are used to dissolve precipitated Mercury Sulphide – potassium chlorate and concentrated hydrochloric acid or aqua regia. These methods are essentially the solution of mercury sulphide by means of nascent chlorine. A third method has been described whereby mercury sulphide is dissolved in a sulphuric acid solution of potassium iodide. This mixture liberates hydrogen iodide which is the dissolving agent. From the equations [complicated equations here] is seems possible that the dissolving action is due to complex formation. It will be seen from equation (1) that the lower the concentration of the sulphideions the greater will be tendency for mercury sulphide to dissolve. This furnishes an explanation why potassium iodide alone cannot be used with same success as hydrogen iodide. With potassium iodide potassium sulphide instead of hydrogen sulphide will be formed during the solution reaction. As potassium sulphide is the salt of a strong base there will remain in solution a high concentration of sulphideions which must promote the back reaction shown in equation (1) and an equilibrium is all that can be attained. It is not possible to reduce the sulphide ion concentration by boiling as it is with hydrogen sulphide since potassium sulphide is non volatile. If the ordinary methods and this new method are compared it is seen that whereas nascent chlorine converts mercury sulphide into mercury chloride, the action of hydrogen iodide is to form a complex salt which has a very low concentration of mercury ions. It is possible therefore that this new method may not give so sensitive a test for mercury. The object of this portion of the work is to ascertain the possibility of testing for mercury in Group II analysis by using the hydrogen iodide method of dissolving the precipitated mercury sulphide and to compare the sensitivity of the test with that of the methods usually employed.

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  • An Inquiry into the mortality from diabetes mellitus in New Zealand, along with some observations and remarks on the Allen treatment of diabetes mellitus.

    Hall, John William (1920)

    Doctoral thesis
    University of Otago

    Date unknown (circa 1920-1930). Code name: Abettor.

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