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A conductimetric investigation of phenomena in extremely dilute aqueous solutions

- Faure, Pierre Knobel

Authors: Faure, Pierre Knobel
Date: 1957
Subjects: Adsorption , Solution (Chemistry)
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:4524 , http://hdl.handle.net/10962/d1014891
Description: 1. The apparatus used in this investigation is fully described, and a new method is outlined for the calibration of bridge resistances "in situ". 2. A chart is given for the accurate correction of weights in air to weights in vacuum for a range of temperatures extending from 10° to 28°C, and for pressures from 690 to 730 mm. 3. An automatic recycling still has been designed for the continuous production of "ultra-pure" water. This still is capable of delivering daily, in routine operation, 16 l. of water of conductivity less than 100 nm/cm after aeration with "C0₂- and NH₃-free" air. 4. A very soluble layer appears to form on the surface of' glass when it is dried; this layer is readily removed on contact with water. 5. The removal of carbon dioxide and of ammonia from aqueous solution by aeration with an indifferent gas has been fully investigated, and it has been shown that these gases can be completely eliminated by such a process. Whereas the carbon dioxide is removed fairly rapidly, however, the ammonia, whether present alone or together with carbon dioxide, only goes out of solution rather slowly. 6. It has been shown that ammonia is adsorbed from aqueous solution on the glass walls of the cell. 7. There does not appear to be any ammonium bicarbonate in the residual impurity left in the "ultra-pure" water obtained from the still; the impurity can, in fact, be regarded as neutral salt with sufficient accuracy for most purposes. 8. The resistance change which accompanies any variation in the rate of bubbling of the stirring gas through the water has been investigated, but no solution has been found as to the cause of this change. 9. A comparison has been made of the efficiency of different gases for stirring purposes, and it seems that, for general work, nitrogen is by far the most suitable of the common gases. 10. The extrapolation to be used for converting resistances to their values at infinite frequency appears ...
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From Pringles of the Valleys

- Pringle, Eric, 1907-, Pringle, Mark Elliot, 1880-, Pringle, John Adams, 1910-

Authors: Pringle, Eric, 1907- , Pringle, Mark Elliot, 1880- , Pringle, John Adams, 1910-
Date: 1957
Subjects: Acacia karroo -- South Africa , Trees -- South Africa
Language: English
Type: mixed material , essay
Identifier: http://hdl.handle.net/10962/109198 , vital:33084
Description: Transcript: "from PRINGLES OF THE VALLEYS ,1957, by Eric, Mark and John Pringle. p.29. (On the farm now known as Clifton). "The next day, July 2nd (1820) was our first Sunday on our own grounds. Feeling deeply the importance of maintaining the suitable observance of this day of sacred rest, it was unanimously resolved that we should strictly abstain from an secular employment not sanctioned by absolute necessity; and at the same time commence such a system of religious services as might be with propriety maintained in the absence of a clergyman or minister. The whole party were accordingly assembled after breakfast under a venerable acacia tree, on the margin of a little stream which murmured around our camp. It was, indeed, an affecting sight to look round on our little band of Scottish emigrants, thus congregated for the first time to worship God in the wild glen allotted for their future home and the heritage of their offspring". An inspection in 1956 established this spot with some certainty is just south of the present Craig Rennie homestead".
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Liquid junction potentials at mixed electrolyte salt bridges

- Finkelstein, Noel Phillip

Authors: Finkelstein, Noel Phillip
Date: 1957
Subjects: Hydrogen-ion concentration -- Measurement , Hydrogen-ion concentration , Electrochemistry
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:4473 , http://hdl.handle.net/10962/d1011835 , Hydrogen-ion concentration -- Measurement , Hydrogen-ion concentration , Electrochemistry
Description: The potentiometric method is one of the most exact techniques of electrochemistry. Its use is widespread in both routine measurements, such as pH determination, and in applications which demand the highest accuracy. Perhaps its severest limitation is the error due to liquid junction potentials. Although this has been the subject of much study, and although various means of combating it have been proposed, it has defied all attempts at a satisfactory solution. Indeed, so serious is the position that it has become the accepted practice in the more accurate fields to abandon altogether the use of potentiometric techniques in favour of others, usually less convenient and otherwise less accurate, when the presence of liquid junctions cannot be avoided. Intro. p. 1.
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Some aspects of the animal ecology of Rhenosterbos: Elytropappus rhinocerotis (L.f.) Less

- Shiff, Clive Julian

Authors: Shiff, Clive Julian
Date: 1957
Subjects: Animal ecology -- South Africa , Rhenosterbos
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:5880 , http://hdl.handle.net/10962/d1013200
Description: Rhenosterbos, Elytropappus rhinocerotis (L.f.) Less belongs to a purely South African section ot the Compositae. It is restricted to an area of low rainfall which is evenly distributed over the year. The plant is a specialised xerophyte with minute leaves and white pubescent twiglets. Older stems become woody and dry and bear no leaves. The shrubs have a life span of about eight years; the plants are most succulent and luxurious during the third and fourth year, after which they tend to become woody and scraggly. For this investigation insect material was obtained by sweep-net collection and field observation. In the Grahamatown district 78 collections were made during the period March - November 1953, with data thus obtained being embodied in this work. In addition to this, collections were made in the Cradock-Hofmeyer, Uitenhage, Riversdale, Bot River, Swellendam and Stellenbosch districts. Twenty species of insects have been shown definitely to feed on the plant and there are another 13 which probably feed on it. Of the 20 species attached to the plant, 12 are sucking forms belonging to the Orders Homoptera and Hemipters. They include six Coccids, two Jassids a Cercopid, two Mirids and a Pentstomid. The Coleoptera are represented by one or perhaps two species which feed on the plant. The Lepidoptera are represented by two important species of moth, a Geometrid and a Pyralid. Four species of gall forming Diptera are associated with the plant. There are two species of Trypetidae which are responsible for piriform swellings of growth points and are distributed evenly throughout the bush. There are also two Cecidomyidae one of which develops in the growth points of the shoots and is responsible tor a minute tubular gall. The other develops in a fusiform stem gall. This latter gall has been shown to be more common on smaller bushes than on larger ones, implying that the adult female may show certain selective powers during oviposition. The size of the insect population is held in check by spiders mantids and other general predators. There are several Coccinellids which prey on the scale insects. Rhenosterbos supports a small, well regulated community of insects. The balance between plant and animal is very dellcate because of the high degree of specialisation of the plant. On occasions this balance has been known to break down, and the insects present in abundance have swamped and killed large patches of the plant.
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Studies on the biology of ants associated with citrus trees

- Myers, N J

Authors: Myers, N J
Date: 1957
Subjects: Citrus -- Diseases and pests -- Biological control -- South Africa , Ants -- South Africa
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:5869 , http://hdl.handle.net/10962/d1012923
Description: Several ant species may be associated with the same honeydew producing insect in citrus orchards. Recently antagonism and competition between two such ants were reported from Letaba. This report stimulated the present study, the purpose of which is to ascertain which ant species are most numerous in citrus orchards ln the Eastern Cape Province; the reasons for these ants being able to occupy orchards; and, finally, their relationships. A survey of the Sundays River Valley and the Fish River Valley revealed that three species - Anoplolepis custodiens Smith, Anoplolepis steingroeveri Forel, and Pheidole megacephala Fabricius - were commonly found in citrus orchards in association with Soft Brown Scale insects. The territorial relationships of these ants were determined by plotting their distribution at intervals for over a year. It was found that this distribution could be correlated with seasonal climatic conditions, the effects of farming practices, brood rearing requirements and behavioural differences between the three species. The ant, A.steingroeveri, had not been previously studied, and since foraging is an integral part of territorial behaviour, some aspects of its biology, and more especially its foraging activity, were investigated to compare it with the known biology of the other two species. Observations on the foraging activity of A. steingroeveri were made at monthly lntervals for almost a year, and correlated with climatic conditions prevailing at the time. Some seasonal and dally variations in foraging behaviour could not be readily explained in terms of the effects of temperature and humidity on the ants. Other factors, includ1ng trophallactic stimulation and overcast skies, were found to influence ant activity. Owing to the apparent lack of information in the literature and possibility of periodic honeydew production by Soft Brown Scale insects controlling ant activity was investigated in the laboratory. The results of this study showed that it was not likely that honeydew excretion restricted the activity of the ants. Several investigators have also found that many interrelated climatic factors correlated with ant foraging behaviour, but have expressed dissatisfaction at not being able to reach the crux of the matter. To clarify the issue a constant temperature chamber was constructed in which a colony of Crematogaster ants was housed and the ants were subjected to a series of temperatures at different humidities, all other factors were eliminated or kept constant. The effects of these two factors on the thermokinetics and foraging activity of the ants were registered. This thesis contains several sections and at the end of each the results are discussed in the light of the available literature and comparisons are drawn between the species under investigation. The main results are given in the summary. After the summary two appendices are included. One is an attempt to compare the effect on ant size of the honeydew diet of orchard colonies with the proteinaceoue diet of veld ants. The other appendix is an experiment to control citrus ants with an insecticide.
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The British organ and its music during the nineteenth century

- Wise, James Patrick Gerald

Authors: Wise, James Patrick Gerald
Date: 1957
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:2694 , http://hdl.handle.net/10962/d1013429
Description: It is a curious fact that, although the literature of the organ is a reasonably large one, no attempt has been made to study the history of the instrument in Britain in any detail. Hopkins and Rimbault covered a certain amount of ground up to 1800, but even they could not deal very extensively with the subject in a volume that was tracing the history of the organ not only in Britain, but throughout Europe, and not only its history but its construction also. For similar reasons Dr. Sumner? (name unclear), in his recent book, could paint little more than an outline picture. However, the British organ's development prior to 1800 was one that does not admit of very discursive treatment. Progress was lamentably slow in comparison with that of Continental organs; and consequently the nineteenth century dawned with British organ-building literally hundreds of years behind that of France, Germany, Belgium and Holland. Yet, a century later, the position was redeemed, and even before the present era opened, the products of British organ-builders were not merely equal to, but, in general superior to those of the Continent in tonal design, mechanism, in artistic finish, and in ordinary maintenance and preservation. The nineteenth century, then, must clearly be regarded as a remarkable, indeed glorious, period in British organ-building, in fact one is tempted to enquire, whether there exists, in the entire artistic and scientific history of any country a similar example of accelerated development; in which one country has made up three hundred years' leeway in one third of that time. This thesis therefore, sets out to examine and describe the events of the century, and the men who were responsible for those events, to trace the growth of the organ in its various departments, and as the instrument itself is only a means to an end, to say something about the way in which it was used, the music that was played on it, and the men who played and composed this music. The thesis is divided into two volumes, the first deals entirely with the history of the instrument and its builders during the nineteenth century, with an introduction briefly recounting the story from the Restoration up to the year 1800; and the second volume is concerned with the music and the musicians as well as the several detailed indexes which are so necessary if a work of this kind is to be of any value at all. A full bibliography is given in Volume Two, but supreme acknowledgement must be paid here to the quarterly periodical "The Organ" - still thriving after an active career that began in July 1921. Its scholarly articles range over the whole field of international organ-building and organ-history, and without its help this thesis would have been far less comprehensive in its scope and far lesss authorative in its source-material.
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The morphology of the Weberian apparatus of Labeo umbratus Smith

- Dennis, Clive Roy

Authors: Dennis, Clive Roy
Date: 1957
Subjects: Fishes -- Anatomy -- South Africa , Weberian apparatus -- Morphology , Fishes -- South Africa -- Tyumie River , Eastern Cape (South Africa) -- Fishes
Language: English
Type: Thesis , Masters , MSc
Identifier: vital:5907 , http://hdl.handle.net/10962/d1014766
Description: In Labeo umbratus only the first three anterior vertebrae undergo any modification. These vertebrae are not completely anchylosed with each other and are closely associated with the four Weberian ossicles. Movement is however restricted between these vertebrae since this is essential for the efficient functioning of the Weberian ossicles. The first vertebra is well developed the absence of a spinous process and neural arch in the first vertebra may perhaps be explained by the findings of some workers who derive the claustrum from the former and the scaphium from the latter. A small muscle has its origin on the claustrum and its insertion in the angle formed by the dorsal and medial processes of the scaphium. A second muscle originates in the pit-like excavation of the first vertebra and is inserted on the ventral process of the scaphium. The intercalarium possesses horizontal, articular and ascending processes; a portion of the horizontal process being imbedded in the interossicular ligament. In Labeo umbratus it is unlikely that the intercalarium represents (if it does so at all) the entire neural arch of the second vertebra. From a morphological point of view it seems likely that the intercalarium may function as a lever. A transversely situated ductus endolymphaticus joins the two sacculi to each other. The sagitta, in the region of the ductus endolymphaticus has a long, lateral "wing-like" process which projects into the cavity of the sacculus. The sacculus anilagena are innervated by the n. saccularis and the n. lagenaris respectively. The ductus endolymphaticus is prolonged posteriorly into a median unpaired sinus endolymphaticus. Although the only serious objection to Weber's theory is the fact that there could be no differential action of the two ears, the basic idea seems valid. Sagemehl's theory cannot be accepted. It seems likely that the Weberian ossicles are necessary structures for audition and to the hydrostatia function of the air-bladder.
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The positive contribution of the religious life to the life of the church

- Clucas, Robert Stephen

Authors: Clucas, Robert Stephen
Date: 1957
Subjects: Religion , Christian life , Anglicans
Language: English
Type: Thesis , Bachelor , BDiv
Identifier: vital:1291 , http://hdl.handle.net/10962/d1014701
Description: The positive contribution of the religious life to the life of the church as a whole. Chapter one: presuppositions of an Anglican, with particular views of ministry, Bible, church and sacraments. Presupposition as regards friendship acknowledgement of influence of C.S. Lewis. Prejudices from outside. The old prejudices, their causes and historical foundation. New prejudices in the present-day world. Chapter two. Misunderstandings from within. The religious life as a higher way of perfection. False view of detachment. Celibacy of the priesthood. Correctives to those misunderstandings. Chapter three. The temporal and the temporary. Contributions which religious life makes continually in a fallen world. The temporary contributions made at different times. Chapter four. The eternal and the inward. Eternal aspects of the threefold vow and of the worship of community life. Contribution of religious throughout the ages to ascetic and mystical theology, which builds on inner life of the Christian. Chapter five. Conclusions and speculations. Re-examination of definition of the religious life. Side developments of the religious life. Three protestant communities. The religious life and present-day problems.
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The struggle for national independence in its international setting : its economic and political background and its manifestation in the Fourth Committee of the United Nations General Assembly

- Lumsden, Geoffrey S

Authors: Lumsden, Geoffrey S
Date: 1957
Subjects: United Nations. General Assembly Self-determination, National Sovereignty Economics -- Political aspects Economic policy
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:1091 , http://hdl.handle.net/10962/d1012790
Description: The decade following the close of the Second World War has been dominated throughout by the clash of political power of the United States and the Soviet Union. Their wartime alliance has crumbled. New, antagonistic alliances have come into existence. The so-called 'EastWest' split, polar in its effect, has forced the admission that prospects of stable peace depend on how successfully bridges can be made to span the gulf. This over-riding and pervading reality has blinded us to the importance of another struggle, which is everywhere mounting in force and intensity and which history may well record as a dominant theme of the twentieth century -- the world-wide struggle for independence. In some cases it has produced revolution and violence: full-scale wars have been fought in its cause in Indonesia and Indo-China; military engagements have taken place in Kenya and Tunisia; Cypriots and British garrison forces have exchanged fire; Malayans have rioted; and 'incidents' too numerous to detail have been reported from a great variety of countries where political dependence exists. Intro., p. 1.
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Verkenninge in die woordeskat van die poësie met spesiale verwysing na N. P. van Wyk Louw

- De Villiers, Aart

Authors: De Villiers, Aart
Date: 1957
Subjects: Louw, N. P. van Wyk (Nicolaas Petrus van Wyk), 1906-1970 -- Criticism and interpretation , Afrikaans poetry -- History and criticism
Language: Afrikaans
Type: Thesis , Masters , MA
Identifier: vital:3644 , http://hdl.handle.net/10962/d1014742
Description: [From Introduction]. Soos die titel aandui, wil hierdie skripsie bloot verkenninge wees. Dit sal vir die leser duidelik wees dat dieselfde metode van benadering wat ek hier op sekere aspekte van die woordeskat van van Wyk Louw se poësie toegepas het, ook op ander woordsoorte toegepas sou kan word, en ook op die werk van ander digters. As 'n mens die gegewens wat jy so verkry, histories sou beskou, sou jy 'n baie interessante kykie kry op die ontwikkeling van die woordeskat in die Afrikaanse poësie. ln die beste van een skripsie is so iets egter, soos duidelik sal blyk, nie moontlik nie. Later, voel ek, sou miskien met vrug op dié grondslag voortgebou kan word.
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