Measurements of the solubilities of some silver halides in water by electrical methods
- Authors: Malan, George McPherson
- Date: 1955
- Subjects: Silver halides -- Solubility , Silver halides -- Analysis , Conductometric analysis , Potentiometry , Silver halides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4515 , http://hdl.handle.net/10962/d1013502
- Description: [Introduction, p. 3] The solubilities of the silver halides cannot be determined by the conventional methods of analytical chemistry because they are too sparingly soluble (of the order 1 x 10⁻⁵ to 1 x 10⁻⁶ g . equiv./1. at 25°C.) However, electrical, and to a lesser extent optical methods, are admirably suited because of their greater sensitivity. The conductometric and potentiometric methods are the two most important electrical techniques for the measurement of the solubilities of sparingly soluble salts, and are the ones employed in this research. There are large discrepancies between the published values for the solubility of silver chloride. Results obtained by the conductometric and potentiometric methods disagree. In addition, figures quoted by independent authors using the same method differ by as much as 15%.
- Full Text:
- Date Issued: 1955
- Authors: Malan, George McPherson
- Date: 1955
- Subjects: Silver halides -- Solubility , Silver halides -- Analysis , Conductometric analysis , Potentiometry , Silver halides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4515 , http://hdl.handle.net/10962/d1013502
- Description: [Introduction, p. 3] The solubilities of the silver halides cannot be determined by the conventional methods of analytical chemistry because they are too sparingly soluble (of the order 1 x 10⁻⁵ to 1 x 10⁻⁶ g . equiv./1. at 25°C.) However, electrical, and to a lesser extent optical methods, are admirably suited because of their greater sensitivity. The conductometric and potentiometric methods are the two most important electrical techniques for the measurement of the solubilities of sparingly soluble salts, and are the ones employed in this research. There are large discrepancies between the published values for the solubility of silver chloride. Results obtained by the conductometric and potentiometric methods disagree. In addition, figures quoted by independent authors using the same method differ by as much as 15%.
- Full Text:
- Date Issued: 1955
Some problems and methods of measuring the growth of African negroid populations
- Myburgh, Corneles Albert Lloyd
- Authors: Myburgh, Corneles Albert Lloyd
- Date: 1955
- Subjects: Africa -- Population -- Statistics , Demography -- Africa , Population forecasting -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3388 , http://hdl.handle.net/10962/d1013560
- Description: A dissertation ... giving details of problems and methods of obtaining statistics of the more important demographic aspects of the African Negroid populations, that is the size of a population, its sex and age distribution, migration movements, deaths and rates of increase.
- Full Text:
- Date Issued: 1955
- Authors: Myburgh, Corneles Albert Lloyd
- Date: 1955
- Subjects: Africa -- Population -- Statistics , Demography -- Africa , Population forecasting -- Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3388 , http://hdl.handle.net/10962/d1013560
- Description: A dissertation ... giving details of problems and methods of obtaining statistics of the more important demographic aspects of the African Negroid populations, that is the size of a population, its sex and age distribution, migration movements, deaths and rates of increase.
- Full Text:
- Date Issued: 1955
Boerdery in die Suid-Afrikaanse Republiek 1858-1899
- Authors: Naudé, Petrus
- Date: 1954
- Subjects: Agriculture -- South Africa -- History -- 19th century , Agricultural laborers -- South Africa -- History , Agriculture -- Economic aspects -- South Africa -- History , Farmers -- South Africa -- History -- 19th century
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1092 , http://hdl.handle.net/10962/d1012946
- Description: In Suid-Afrika het die opkoms van die sosialistiese gedagte teen die einde van die negentiende eeu ook merkbare invloed op die staatshuishouding gehad. In die negentiende eeu was die ekonomiese wetgewing, hoofsaaklik onder invloed van die indiwidualisme volgens die leer van "Laissez- faire", daarop gerig om die maksimum welvaart te verkry deur vrye mededinging aan te moedig en te beskerm, en om privaat inisiatief sy gang te laat gaan. Daar het egter geleidelik 'n verandering in hierdie houding en beleid ingetree. Deur 'n verandering in die beskouing omtrent die einddoel van die menslike arbeid en sy ekonomiese bedrywigheid moes die staat uit sosiaal-ekonomiese oorwegings sekere seksies van die samelewing deur spesiale en beskermende wetgewing te hulp kom. Die ontwikkeling van die aandeel wat die staat geneem het in die beheer en bevordering van die welvaart van die boere in die Suid-Afrikaanse Republiek is ' n voorbeeld van die voorgenoemde omwenteling in die ekonomiese en bedryfslewe teen die einde van die vorige eeu. Die staat het aanvanklik weinig gedoen vir die bevordering en beheer van die onderhoudsboerdery. Later, met die veranderde boerderyekonomie, het staatshulp, staatsvoorligting en -beheer egter noodsaaklik geword. Gedurende die laaste jare van die Suid- Afrikaanse Republiek het die owerheid meer en meer verpligtings teenoor die boeregemeenskap aanvaar. Namate die staat groter hulp en diens verskaf het, na dié mate moes hy ook groter beheer uitoefen.
- Full Text:
- Date Issued: 1954
- Authors: Naudé, Petrus
- Date: 1954
- Subjects: Agriculture -- South Africa -- History -- 19th century , Agricultural laborers -- South Africa -- History , Agriculture -- Economic aspects -- South Africa -- History , Farmers -- South Africa -- History -- 19th century
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1092 , http://hdl.handle.net/10962/d1012946
- Description: In Suid-Afrika het die opkoms van die sosialistiese gedagte teen die einde van die negentiende eeu ook merkbare invloed op die staatshuishouding gehad. In die negentiende eeu was die ekonomiese wetgewing, hoofsaaklik onder invloed van die indiwidualisme volgens die leer van "Laissez- faire", daarop gerig om die maksimum welvaart te verkry deur vrye mededinging aan te moedig en te beskerm, en om privaat inisiatief sy gang te laat gaan. Daar het egter geleidelik 'n verandering in hierdie houding en beleid ingetree. Deur 'n verandering in die beskouing omtrent die einddoel van die menslike arbeid en sy ekonomiese bedrywigheid moes die staat uit sosiaal-ekonomiese oorwegings sekere seksies van die samelewing deur spesiale en beskermende wetgewing te hulp kom. Die ontwikkeling van die aandeel wat die staat geneem het in die beheer en bevordering van die welvaart van die boere in die Suid-Afrikaanse Republiek is ' n voorbeeld van die voorgenoemde omwenteling in die ekonomiese en bedryfslewe teen die einde van die vorige eeu. Die staat het aanvanklik weinig gedoen vir die bevordering en beheer van die onderhoudsboerdery. Later, met die veranderde boerderyekonomie, het staatshulp, staatsvoorligting en -beheer egter noodsaaklik geword. Gedurende die laaste jare van die Suid- Afrikaanse Republiek het die owerheid meer en meer verpligtings teenoor die boeregemeenskap aanvaar. Namate die staat groter hulp en diens verskaf het, na dié mate moes hy ook groter beheer uitoefen.
- Full Text:
- Date Issued: 1954
Some measurements of the conductivities of dilute potassium chloride solutions
- Authors: Faure, Abraham
- Date: 1954
- Subjects: Potassium chloride
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4471 , http://hdl.handle.net/10962/d1011787
- Description: A constant temperature room has been constructed in which the thermoregulator is controlled by a temperature-sensitive resistance. A thermostat has been constructed in which the 0 temperature is controlled to within 0.001°C. A precision conductance bridge has been built in a very convenient form. Improvements include the replacement of the telephone as null detector by a cathode ray oscilloscope, and the use of a resistance-capacity phase-shift oscillator, which gives a good wave-form. An automatic recycling conductance water still has been built which regularly gives water with a conductivity less than 0.09 micromhos per cm. The conductivities of dilute KCl solutions have been measured, taking special care to prevent errors due to the adsorption of KCl on the surface of glass. Two cells were used for these measurements : a modified Jones cell, and a special conductimetric titration cell. The modified Jones cell has given results in good agreement with the generally-accepted values. The results of the conductimetric titration cell do not agree well with the generally-accepted values; the greatest difference (for the most dilute solution) is 0.4%. The reason for this is not known.
- Full Text:
- Date Issued: 1954
- Authors: Faure, Abraham
- Date: 1954
- Subjects: Potassium chloride
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4471 , http://hdl.handle.net/10962/d1011787
- Description: A constant temperature room has been constructed in which the thermoregulator is controlled by a temperature-sensitive resistance. A thermostat has been constructed in which the 0 temperature is controlled to within 0.001°C. A precision conductance bridge has been built in a very convenient form. Improvements include the replacement of the telephone as null detector by a cathode ray oscilloscope, and the use of a resistance-capacity phase-shift oscillator, which gives a good wave-form. An automatic recycling conductance water still has been built which regularly gives water with a conductivity less than 0.09 micromhos per cm. The conductivities of dilute KCl solutions have been measured, taking special care to prevent errors due to the adsorption of KCl on the surface of glass. Two cells were used for these measurements : a modified Jones cell, and a special conductimetric titration cell. The modified Jones cell has given results in good agreement with the generally-accepted values. The results of the conductimetric titration cell do not agree well with the generally-accepted values; the greatest difference (for the most dilute solution) is 0.4%. The reason for this is not known.
- Full Text:
- Date Issued: 1954
Studies in the comparative anatomy and systematic importance of the hexapod tentorium
- Authors: Hudson, Gerda Bland
- Date: 1954
- Subjects: Insects -- Anatomy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5858 , http://hdl.handle.net/10962/d1012457
- Description: During a study of the morphology of the orthopteroid Hexapoda between the years 1939-1941, it appeareded to the writer that further investigation into the structure of the insect tentorium was necessary. The early entomologists laid the foundation or our knowledge or the tentorium but during the latter half of the last century little was added in this particulart field. Comstock and Kochi (1902), as far as the writer is aware are the only workers who have published a paper devoted entirely to the skeleton of the bead of insects, and they did much to clarify both nomenclature and existing knowledge of this structure at that time. Berlese (1909) described a typical tentorlum as observed in orthopteroid Hexapoda and then considered the variations of the tentorium which occur in other groups of insects. Some confusion then appears to have arisen amongst workers, over the origin of the dorsal arms which were erroneously considered by some to be cuticular invaginations and not secondary outgrowths of the anterior tentorial arms. Certain morphologists amongst them, Hoke (1924) Denis (1928), Snodgrass (1928, 1935), Hansen (1930), Walker (1933) Imms (1934), and Symmons (1952), have done much towards improving our knowledge of the tentorium, but all too frequently workers offer brief and inadequate descriptions of this structure in otherwise comprehensive investigations of the insect head. Themain objects in this study are threefold, vlz. (1) The claification of nomenclature (2) The examination and the interpretation ot the tentorium in certain groups of insects. (3) The deliberation as to whether the tentorium is of phylogenetic significance, and thus of use in assessing various schemes of insect classification which have been presented. Introduction, p. 1-2.
- Full Text:
- Date Issued: 1954
- Authors: Hudson, Gerda Bland
- Date: 1954
- Subjects: Insects -- Anatomy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5858 , http://hdl.handle.net/10962/d1012457
- Description: During a study of the morphology of the orthopteroid Hexapoda between the years 1939-1941, it appeareded to the writer that further investigation into the structure of the insect tentorium was necessary. The early entomologists laid the foundation or our knowledge or the tentorium but during the latter half of the last century little was added in this particulart field. Comstock and Kochi (1902), as far as the writer is aware are the only workers who have published a paper devoted entirely to the skeleton of the bead of insects, and they did much to clarify both nomenclature and existing knowledge of this structure at that time. Berlese (1909) described a typical tentorlum as observed in orthopteroid Hexapoda and then considered the variations of the tentorium which occur in other groups of insects. Some confusion then appears to have arisen amongst workers, over the origin of the dorsal arms which were erroneously considered by some to be cuticular invaginations and not secondary outgrowths of the anterior tentorial arms. Certain morphologists amongst them, Hoke (1924) Denis (1928), Snodgrass (1928, 1935), Hansen (1930), Walker (1933) Imms (1934), and Symmons (1952), have done much towards improving our knowledge of the tentorium, but all too frequently workers offer brief and inadequate descriptions of this structure in otherwise comprehensive investigations of the insect head. Themain objects in this study are threefold, vlz. (1) The claification of nomenclature (2) The examination and the interpretation ot the tentorium in certain groups of insects. (3) The deliberation as to whether the tentorium is of phylogenetic significance, and thus of use in assessing various schemes of insect classification which have been presented. Introduction, p. 1-2.
- Full Text:
- Date Issued: 1954
The chemistry of naturally occurring long chain unsaturated compounds
- Authors: Silk, M H
- Date: 1954
- Subjects: Compounds, Unsaturated
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4518 , http://hdl.handle.net/10962/d1014332
- Description: [From Introduction, p. 3] Raw marine oils are subject to considerable variation in composition with season and are moreover very unbalanced oils for direct use in the paint industry. Further refining is undertaken chiefly by Messrs Marine Oil Refiners of Africa Ltd., whose factory is situated at Simonstown. In their plant marine oils and others are treated by the Solexol process involving counter current extraction of the oil with liquid propane in a tower over which a temperature gradient is maintained. The process achieves the removal of a large proportion of the relatively saturated glycerides, the natural antitioxidants, and the relatively highly unsaturated components, all of which are detrimental to the eventual formation of good paint films. The segregated marine oil from the Solexol process is then bodied or polymerised at high temperatures to yield a "drying oil" which is used as a substitute for bodied linseed oil in paints. The chemical reactions taking place during the polymerisation and drying of these oils are of an exemely complex nature, and for their understanding it is necessary to have an accurate knowledge of the chemical nature of the component fatty acids in the natural glycerides ... The term "marine oils" in this work should be understood to mean marine fish body oils, marine mammal oils being excluded from consideration.
- Full Text:
- Date Issued: 1954
- Authors: Silk, M H
- Date: 1954
- Subjects: Compounds, Unsaturated
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4518 , http://hdl.handle.net/10962/d1014332
- Description: [From Introduction, p. 3] Raw marine oils are subject to considerable variation in composition with season and are moreover very unbalanced oils for direct use in the paint industry. Further refining is undertaken chiefly by Messrs Marine Oil Refiners of Africa Ltd., whose factory is situated at Simonstown. In their plant marine oils and others are treated by the Solexol process involving counter current extraction of the oil with liquid propane in a tower over which a temperature gradient is maintained. The process achieves the removal of a large proportion of the relatively saturated glycerides, the natural antitioxidants, and the relatively highly unsaturated components, all of which are detrimental to the eventual formation of good paint films. The segregated marine oil from the Solexol process is then bodied or polymerised at high temperatures to yield a "drying oil" which is used as a substitute for bodied linseed oil in paints. The chemical reactions taking place during the polymerisation and drying of these oils are of an exemely complex nature, and for their understanding it is necessary to have an accurate knowledge of the chemical nature of the component fatty acids in the natural glycerides ... The term "marine oils" in this work should be understood to mean marine fish body oils, marine mammal oils being excluded from consideration.
- Full Text:
- Date Issued: 1954
The rehabilitative value of sub-economic housing as illustrated by Schauder Township, Port Elizabeth, Cape Province, Union of South Africa, 1938-1948
- Authors: Stoker, F M L
- Date: 1954
- Subjects: Housing rehabilitation -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3389 , http://hdl.handle.net/10962/d1014554
- Description: [From Introductory discussion]. The modern approach to any sociological problem is characterised by the attempt to analyse the contributory factors in such a way that their inter-active association is clearly discernible. The simple concept of "single cause and effect" is now recognised to be a traversity of social fact. Social Pathology, therefore, may be said to attempt to isolate the multiple factors involved in a given situation, and to endeavour to determine thelr mode of inter-action in order that remedial techniques may be applied effectively. Slum conditions are obviously pathologic, by which it is understood that the environment imposes strains upon the individual to which there is ineffective adjustment. The rehabilitation of such a population would involve the converse process, restoring individuals to a condition where they are able to cope in every respect with the demands of life at their respective class levels. It is very rare indeed that only a single factor is involved in a social pathological condition and for this reason it is quite possible that one- sided efforts at rehabilitation - such as the attempt to re-house ALL slum dwellers in sub-economic houses - have a tendency to increase the pathology in another direction. Rehabilitation must therefore be based on multi-factorial analysis in which allowance is, as far as possible, made for the inter-connection of each of the individual deviations from the normal. The aim of this thesis is to evaluate the effect of good housing conditions on the 2335 Coloured slum families re-housed in sub-economic houses at Schauder Township, Port Elizabeth, from the time that these houses were first available for occupancy.
- Full Text:
- Date Issued: 1954
- Authors: Stoker, F M L
- Date: 1954
- Subjects: Housing rehabilitation -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3389 , http://hdl.handle.net/10962/d1014554
- Description: [From Introductory discussion]. The modern approach to any sociological problem is characterised by the attempt to analyse the contributory factors in such a way that their inter-active association is clearly discernible. The simple concept of "single cause and effect" is now recognised to be a traversity of social fact. Social Pathology, therefore, may be said to attempt to isolate the multiple factors involved in a given situation, and to endeavour to determine thelr mode of inter-action in order that remedial techniques may be applied effectively. Slum conditions are obviously pathologic, by which it is understood that the environment imposes strains upon the individual to which there is ineffective adjustment. The rehabilitation of such a population would involve the converse process, restoring individuals to a condition where they are able to cope in every respect with the demands of life at their respective class levels. It is very rare indeed that only a single factor is involved in a social pathological condition and for this reason it is quite possible that one- sided efforts at rehabilitation - such as the attempt to re-house ALL slum dwellers in sub-economic houses - have a tendency to increase the pathology in another direction. Rehabilitation must therefore be based on multi-factorial analysis in which allowance is, as far as possible, made for the inter-connection of each of the individual deviations from the normal. The aim of this thesis is to evaluate the effect of good housing conditions on the 2335 Coloured slum families re-housed in sub-economic houses at Schauder Township, Port Elizabeth, from the time that these houses were first available for occupancy.
- Full Text:
- Date Issued: 1954
Die evolusie van nedersetting in die Sondagsriviervallei
- Authors: Potgieter, J M
- Date: 1953
- Subjects: Land settlement -- South Africa -- Sundays River Valley , Agriculture -- South Africa -- Sundays River Valley , Irrigation -- South Africa -- Eastern Cape -- Sundays River Valley
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4875 , http://hdl.handle.net/10962/d1013041
- Description: Soos die titel aandui is hierdie verhandeling 'n volledige en noukeurige oorsig van die evolusie (ontwikkeling) van blanke nedersetting in die Sondagsriviervallei. Dis die eerste poging wat aangewend is om die ontwikkeling op alle gebiede van die grondlegging af tot op die huidige datum teen 'n geskiedkundige agtergrond te skilder. Maar dwarsdaur is daar getrag om 'n duidelike begrip van die interaksie van natuur en mens te handhaaf.
- Full Text:
- Date Issued: 1953
- Authors: Potgieter, J M
- Date: 1953
- Subjects: Land settlement -- South Africa -- Sundays River Valley , Agriculture -- South Africa -- Sundays River Valley , Irrigation -- South Africa -- Eastern Cape -- Sundays River Valley
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4875 , http://hdl.handle.net/10962/d1013041
- Description: Soos die titel aandui is hierdie verhandeling 'n volledige en noukeurige oorsig van die evolusie (ontwikkeling) van blanke nedersetting in die Sondagsriviervallei. Dis die eerste poging wat aangewend is om die ontwikkeling op alle gebiede van die grondlegging af tot op die huidige datum teen 'n geskiedkundige agtergrond te skilder. Maar dwarsdaur is daar getrag om 'n duidelike begrip van die interaksie van natuur en mens te handhaaf.
- Full Text:
- Date Issued: 1953
The chemistry of the wattle tannins
- Authors: Roux, David Gerhardus
- Date: 1953
- Subjects: Tannin plants , Tannins , Wattles (Plants)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:4492 , http://hdl.handle.net/10962/d1013098
- Description: Four species of acacia of Auatralian origin are associated with the wattle industry in South Africa. Black wattle, Acacia mollissima willd., is the most important of these and is today almost exclusively cultivated. The tree grows successfully only in a limited area of rich soil and high rainfall and is easily affected by adverse conditions caused by insect pests, frost damage and drought. Expansion of the area under cultivation is therefore, not feasible, although the world demand for vegetable extracts far exceeds the available supply. The remaining species such as green (Acacia decurrrens willd.) and silver wattles (Acacia dealbata Link.) possess many desirable characteristics which resist such adverse factors. Their barks, however, give reddish extracts, which are considered unsuitable for tannery usage because of the red colour they impart to the leather. Hybridisation studies, involving the crossing of green and silver wattle with the black, and aimed at produc1ng progenies containing many of the desirable characterlstics of the parent plants, are thus a natural result and have been in progress for a considerable period. Summary, p. i.
- Full Text:
- Date Issued: 1953
- Authors: Roux, David Gerhardus
- Date: 1953
- Subjects: Tannin plants , Tannins , Wattles (Plants)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: vital:4492 , http://hdl.handle.net/10962/d1013098
- Description: Four species of acacia of Auatralian origin are associated with the wattle industry in South Africa. Black wattle, Acacia mollissima willd., is the most important of these and is today almost exclusively cultivated. The tree grows successfully only in a limited area of rich soil and high rainfall and is easily affected by adverse conditions caused by insect pests, frost damage and drought. Expansion of the area under cultivation is therefore, not feasible, although the world demand for vegetable extracts far exceeds the available supply. The remaining species such as green (Acacia decurrrens willd.) and silver wattles (Acacia dealbata Link.) possess many desirable characteristics which resist such adverse factors. Their barks, however, give reddish extracts, which are considered unsuitable for tannery usage because of the red colour they impart to the leather. Hybridisation studies, involving the crossing of green and silver wattle with the black, and aimed at produc1ng progenies containing many of the desirable characterlstics of the parent plants, are thus a natural result and have been in progress for a considerable period. Summary, p. i.
- Full Text:
- Date Issued: 1953
German immigration to the Cape, with special reference to (a) the German military settlers of 1857; and (b) the German immigrants of 1858
- Authors: Schnell, E L G
- Date: 1952
- Subjects: Germans -- South Africa -- Cape of Good Hope , Immigrants -- South Africa -- Cape of Good Hope , Cape of Good Hope (South Africa) -- History , Eastern Cape (South Africa) -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2613 , http://hdl.handle.net/10962/d1013168
- Description: South Africa is a multi-racial society in more than one sense. There are the broad divisions of Colour, but in addition there are further divisions within each group. The European section is mostly of Dutch and British origin, but there are important other strains, notably the French and the German. The history of the Dutch and British sections has been written, and that of the French too, but the story of the German element is still incomplete. Preface.
- Full Text:
- Date Issued: 1952
- Authors: Schnell, E L G
- Date: 1952
- Subjects: Germans -- South Africa -- Cape of Good Hope , Immigrants -- South Africa -- Cape of Good Hope , Cape of Good Hope (South Africa) -- History , Eastern Cape (South Africa) -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2613 , http://hdl.handle.net/10962/d1013168
- Description: South Africa is a multi-racial society in more than one sense. There are the broad divisions of Colour, but in addition there are further divisions within each group. The European section is mostly of Dutch and British origin, but there are important other strains, notably the French and the German. The history of the Dutch and British sections has been written, and that of the French too, but the story of the German element is still incomplete. Preface.
- Full Text:
- Date Issued: 1952
A study of conditions in the upper atmosphere and their deduction from radio measurements
- Gledhill, J A, Szendrei, M E
- Authors: Gledhill, J A , Szendrei, M E
- Date: 1948
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21181 , http://hdl.handle.net/10962/6795
- Description: Summary: In part 1 (a), after a brief historical outline of methods of ionospheric investigation and their development, the construction in this laboratory of manually operated equipment for sounding the ionosphere is described. Photographic records of good definition were taken at regular intervals over a period of four months during the summer of 1945-6. These were fully sealed for critical frequencies, true heights and thicknesses of all the layers present, and mean monthly values of these quantities for each hour are tabulated. An extensive correlation with magnetic data from Hermanus indicated good correlation between magnetic activity and disturbed ionospheric conditions. On these grounds some disturbed days were rejected, and others were eliminated on ionospheric grounds. Smoothed mean values are tabulated and graphs drawn. These are presented in concise form on "electron density maps", which are graphs showing lines of constant electron density plotted as functions of time and height. In part 1 (b), a new theory of layer-formation is developed, in which the temperature is assumed to vary linearly with height. The equations are compared at each step with those obtained by Chapman in his theory of layer-formation in an isothermal atmosphere. The equations for the maximum of electron density and its height are also given. The effect of the parameters on the shape of the layer is shown in graphical form. The equations are somewhat complex in form, but an ingenious graphical method has been devised suitable for the application of the theory to results given in the form of those in section 1 (a). From this application values are obtained for the temperature gradient, the temperature at 200 km. and its variation over the middle part of the day. The results obtained are in accordance with previous estimates, and offer numerical confirmation of the theory that the atmosphere expands bodily upwards during the middle part of a summer day.
- Full Text:
- Date Issued: 1948
- Authors: Gledhill, J A , Szendrei, M E
- Date: 1948
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21181 , http://hdl.handle.net/10962/6795
- Description: Summary: In part 1 (a), after a brief historical outline of methods of ionospheric investigation and their development, the construction in this laboratory of manually operated equipment for sounding the ionosphere is described. Photographic records of good definition were taken at regular intervals over a period of four months during the summer of 1945-6. These were fully sealed for critical frequencies, true heights and thicknesses of all the layers present, and mean monthly values of these quantities for each hour are tabulated. An extensive correlation with magnetic data from Hermanus indicated good correlation between magnetic activity and disturbed ionospheric conditions. On these grounds some disturbed days were rejected, and others were eliminated on ionospheric grounds. Smoothed mean values are tabulated and graphs drawn. These are presented in concise form on "electron density maps", which are graphs showing lines of constant electron density plotted as functions of time and height. In part 1 (b), a new theory of layer-formation is developed, in which the temperature is assumed to vary linearly with height. The equations are compared at each step with those obtained by Chapman in his theory of layer-formation in an isothermal atmosphere. The equations for the maximum of electron density and its height are also given. The effect of the parameters on the shape of the layer is shown in graphical form. The equations are somewhat complex in form, but an ingenious graphical method has been devised suitable for the application of the theory to results given in the form of those in section 1 (a). From this application values are obtained for the temperature gradient, the temperature at 200 km. and its variation over the middle part of the day. The results obtained are in accordance with previous estimates, and offer numerical confirmation of the theory that the atmosphere expands bodily upwards during the middle part of a summer day.
- Full Text:
- Date Issued: 1948
The preservation and standardisation of South African hides and skins
- Authors: Kritzinger, Carl Cronje
- Date: 1946
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21052 , http://hdl.handle.net/10962/6157
- Description: During the past fifty years the problems of the leather industry have been tackled from various aspects by scientific research workers all over the world, and "works control" today forms one of .the important foundation stones of efficiently run tanneries and footwear factories. The raw materials of the tanning industry, hides and skins, constitute the largest proportion of the cost of production, and it is ' only natural that the improvement of these valuable raw materials should be given primary attention by any leather scientist. Until only a few years ago, however, the South African hide and skin industry was at a serious ·disadvantage in that it had to base recommendations for improved production methods almost exclusively on overseas experience and practice. The importance of the differences existing between South Africa and European or American countries with regard to climate, slaughtering, hide and skin production in general, transport and sale, however, necessitates a different approach to our specific problems. The overseas hide and skin industry has had, since the beginning of this century, the support and particularly the guidance of scientific research; but it was not until 1935, when, through the support of the Hide and Skin advisory Board, Prof. W. F. Barker founded the original Tanning, Hides and Skins Research Department at Rhodes University College, Grahamstown, that science actively entered the field of hide and skin production in this country. Much of the work done had of course to be based on the results obtained by overseas research institutions, and the adaptation of such results to suit our own problems for some time formed a considerable part of the investigations undertaken. This thesis embodies the results of work undertaken by the writer since 1943 on specific problems of the South African hide and skin industry. Much of the work has already received publication through the Circulars and Journals of this Institute, but it is embodied here again in order to maintain the continuity. The attitude throughout has been to evolve methods of production suited to our own conditions, and the adoption of the recommendations contained in this thesis should lead to improvement in the quality of our hides and skins. Much still remains to be done, and it is the sincere hope of the writer that this work will stimulate and form the basis for subsequent investigations. For that reason more or less detailed descriptions are given of all experiments conducted, and the theory of curing in its relation to tanning is briefly discussed . The literature in each of the four Parts has been attached at the end of that Part to facilitate reference work. At the same time, however, the writer kept in mind the requirements of the trade itself, therefore much of the work is discussed in popular terms. It is hoped that the correct balance between the two extremes has been arrived at.
- Full Text:
- Date Issued: 1946
- Authors: Kritzinger, Carl Cronje
- Date: 1946
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:21052 , http://hdl.handle.net/10962/6157
- Description: During the past fifty years the problems of the leather industry have been tackled from various aspects by scientific research workers all over the world, and "works control" today forms one of .the important foundation stones of efficiently run tanneries and footwear factories. The raw materials of the tanning industry, hides and skins, constitute the largest proportion of the cost of production, and it is ' only natural that the improvement of these valuable raw materials should be given primary attention by any leather scientist. Until only a few years ago, however, the South African hide and skin industry was at a serious ·disadvantage in that it had to base recommendations for improved production methods almost exclusively on overseas experience and practice. The importance of the differences existing between South Africa and European or American countries with regard to climate, slaughtering, hide and skin production in general, transport and sale, however, necessitates a different approach to our specific problems. The overseas hide and skin industry has had, since the beginning of this century, the support and particularly the guidance of scientific research; but it was not until 1935, when, through the support of the Hide and Skin advisory Board, Prof. W. F. Barker founded the original Tanning, Hides and Skins Research Department at Rhodes University College, Grahamstown, that science actively entered the field of hide and skin production in this country. Much of the work done had of course to be based on the results obtained by overseas research institutions, and the adaptation of such results to suit our own problems for some time formed a considerable part of the investigations undertaken. This thesis embodies the results of work undertaken by the writer since 1943 on specific problems of the South African hide and skin industry. Much of the work has already received publication through the Circulars and Journals of this Institute, but it is embodied here again in order to maintain the continuity. The attitude throughout has been to evolve methods of production suited to our own conditions, and the adoption of the recommendations contained in this thesis should lead to improvement in the quality of our hides and skins. Much still remains to be done, and it is the sincere hope of the writer that this work will stimulate and form the basis for subsequent investigations. For that reason more or less detailed descriptions are given of all experiments conducted, and the theory of curing in its relation to tanning is briefly discussed . The literature in each of the four Parts has been attached at the end of that Part to facilitate reference work. At the same time, however, the writer kept in mind the requirements of the trade itself, therefore much of the work is discussed in popular terms. It is hoped that the correct balance between the two extremes has been arrived at.
- Full Text:
- Date Issued: 1946