Browsing by Author "Rapson, W S"

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    A study of lipids from animal skin secretions
    (1955) Hougen, Frithjof Wilhelm; Pugh, W; Holliman, F G; Rapson, W S
    Within the akin of animals are situated various glands which secrete their products to the outer surface of the skin. The glands exist in many forms and their functions are diverse. A satisfactory classification based on the morphology of the glands has been worked out and the glands of the vertebrata are recognised as belonging to three main types: - holocrine, eccrine and apocrine glands. In man the holocrine glands are referred to as sebaceous and the eccrine as sudoriferous or sweat glands. These terms are often used also for animals. Comparatively few animal skin glands or secretions have been investigated chemically. The sebaceous secretion of the sheep, wool wax, has been much investigated owing to the commercial value of this product; and the author participated for some years in studies of wool wax at the National Chemical Research Laboratory, Pretoria. In Chapter I is summarised the present knowledge of wool wax chemistry, including contributions from this laboratory into the investigation of dihydric alcohols and hydroxy-acids and the syntheses of iso-acids which occur in wool wax. Skin secretions which have no commercial applications are nevertheless of great interest from a physiological and biochemical point of view. In this respect human skin secretions may naturally attract more attention than those of other animals. Their investigation may prove rewarding in throwing further light upon the studies of dermatological disorders in general, and more particularly upon the all-important problem of skin cancer. A study of human sebaceous secretions was taken up in this laboratory by the author; the aliphatic alcohols and some polycyclic hydrocarbons present were investigated. The chemistry of human sebaceous secretions is reviewed in Chapter II. Chapter III reviews work of other investigators on various skin gland secretions. The "scent" glands of musk deer and other animals and the "preen" glands of some birds have been investigated. Some materials of human origin such as ear wax, which are considered as related to sebaceous secretions, are included in this review. Natural fats and waxes are generally of complex composition and early workers did not succeed in isolating many pure components from such materials. As a result of improved techniques and methods considerable progress has been made in the last few years towards the elucidation of the fine structures of fats and waxes.
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    A study of oil-bearing seeds from indigenous plants
    (1951) Lighthelm, Salomon Petrus; Rapson, W S
    In the course of this investigation, the seeds and fruit of the following species have been investigated: (1) Three members of the genus Ximenia viz., X. caffra Sond., X caffra var. natalensis Sond. and X. americana var. microphylla Welw., commonly known as "sour plum". (2) Sclerocarva caffra Sond., commonly known as Maroola. (3) Three members of the Strychnos family viz. Strychnos innocua, Strychnos dysophylla and Strychnos Scoccoloides. The oil content of the kernels of the Ximenia species and of Sclerocarva caffra Sond. has been determined, as well as the oil content of the fruit pulp and kernels of the Strychnos species. As the oil content of the fruit of the Strychnos species was found to be extremely low, work on these species was not carried further. The composition of the kernel oils of the other species was, however, determined. The absorption spectra of the oils from the Ximenia species revealed the presence of a conjugated acid. This acid has been isolated and characterised as Octadeca-11-ene-9-ynoic acid, the common name Ximenynic acid, is proposed for it. Two other unsaturated acids, Ximenic acid and Lumeniqueic acid were isolated in 95-97% purity.
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    The crystal structure and constitution of some molecular complexes of 4:4- dinitrodiphenyl
    (1947) Saunder, Douglas Harold; Saunder, Douglas Harold; James, R W; Rapson, W S
    The crystal structures or a number of molecular complexes formed by 4:4'-dinitrodiphenyl with various diphenyl derivatives are described. The general type of structure is undoubtedly the same for all the complexes examined and the typical arrangement may be taken as that in the complex of 4:4'-dinitrodiphenyl with 4-hydroxydiphenyl, the structure of which has been fully determined. As shown in fig. 7 the dinitrodiphenyl molecules form layers in face-centred array and lie one above the other with a spacing of about 3.7 A. The arrangement of these molecules alone is such that a set of tubular cavities, also in face-centred array, run through the structure. In the complexes these cavities are occupied by the other component molecules, the hydroxydiphenyl molecules in the case considered; which thus lie nearly normal to the planes containing the dinitrodiphenyl molecules and are seen end-on in fig. 7. In the other structures examined geometrical and symmetry conditions require that the individual molecules should be tilted in varying degrees, but the type or structure still remains essentially the same. It is shown that the ratio of the components in these complexes is determined by the length of the molecule other than dinitrodiphenyl, and that in no case is it necessary for the intermolecular distances to be shorter than those found in crystals or ordinary aromatic nitro-compounds. A bonding mechanism in terms of dipole attraction between the component molecules is shown to be consistent with all the observed data. Of interest are the periodic distortions which appear to occur in the crystal lattices of the complexes or 4:4'-dinitrodiphenyl with 4-iodo-, 4-bromo- and 4-chlorodiphenyl.