Physico-chemical investigations on varietal differences in rice. III. Electrical conductivities of rice suspensions in water

The increase in conductivity with time of rice and rice powder suspensions in water has been studied at different temperatures. Varietal differences in the rates of increase have been observed, but they are not characteristic of quality. The increase in conductivity cannot be attributed to electrolytes liberated by hydrolysis of amylopectin as such hydrolysis is inappreciable, but is to be accounted for, by the dissolution of electrolytes already present in the free state in rice

The mechanisms of the clarification of muddy water by Strychnos potatorum seeds

Clarification of muddy water by paste prepared from Strychnos potatorum seeds is due to the combined action of colloids and alkaloids present in the seeds. The albumin and other colloids sensitise the suspension and the coagulation is then caused by the alkaloid ions. The paste, if used in excess, fails to clarify the water. An optimum concentration of paste is therefore to be employed for efficient clarification

Pulsations on mercury surface caused by polarisation

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Efficiency of wetting agents

The relative efficiencies of some of the common wetting agents have been determined by measuring the surface tension of five-minute-old surfaces of the solutions using the ring method in a modified form. Aqueous solutions giving a surface tension of 37 dynes per cm. may be considered to have good wetting properties. It is found that wetting power is not necessarily associated with detergent and emulsifying properties. Salts greatly increase wetting power. Bivalent cations are more effective than univalent cations in increasing wetting power. A moderate degree of hardness in water employed in preparing solutions of wetting agents may be of advantage in the textile industry. The maximum bubble pressure method is shown to be unsuitable for the measurement of surface tension of solutions which show a variation with time. A rough idea of the order of wetting efficiencies of wetting agents can however be obtained by measuring the surface tension of a five-second-old surface by this method

Aging of surfaces of solutions. Part VI. Surface aging of casein solutions

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Spreading of casein and derivatives

1. Casein has been spread from its aqueous solutions by different methods and it has been found that the modified band method is the most suitable for the study of protein films. 2. Effect of salts on the spreading of casein has been studied. The results obtained can be explained on the basis that two different factors, solubility and the electric charge of the protein molecule influence spreading. 3. Treatment of the protein with formaldehyde causes a decrease in spreading. Change in pH affects spreading of formolised casein to a smaller degree. 4. Sodium metaphosphate diminishes markedly the spreading of casein. Trichloracetic acid, however, has no effect. 5. Deaminisation of casein alters the spreading properties and gives unstable films on acidulated water. No films can be got on distilled water. 6. The spreading properties of an isodisperse fraction of casein have been studied. The limiting area of this fraction has been found to be of the same order as that of the original material

Effect of electric field on Tyndall scattering

The study of the action of an electric field on the scattering intensity of sols has thus led to interesting results. The study is useful in determining the shape of the particles. The present technique would be supplementary to the studies of double refraction, in that the latter cannot be conveniently investigated in a highly scattering system. With slightly conducting sols, large fields can be used so as to produce saturation effects. Under such conditions, the use of rotating fields would bring about a unique orientation of the discs. A superposition of two A.C. fields of different cycles at right angles to each other would have the same effect as the circular field. The use of elliptical fields would reveal any want of equality of the two axes in the plane of discs of flat particles. The technique itself is simpler than the flow technique. Since there is often a large difference in the dielectric constant between the particles and the medium, the orientation is marked even with small fields, and the electric field is thus more powerful than the magnetic field in bringing about orientation

Studies in the chemical behaviour of sulphur compounds. Part I. The hydrolysis of sulphur chloride

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Studies in the chemical behaviour of sulphur compounds. Part II. Disulphur oxide

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Studies in adsorption on gels. I. A comparative study of selective adsorption from binary mixtures of liquids on gels of silica, alumina and ferric oxide

The effect of temperature of activation on the capillary space in alumina and ferric oxide gels has been studied. Structural changes in alumina gel have been noticed in the neighbourhood of 500°C. and 900°C. and their significance discussed. Adsorption on alumina and ferric oxide gels from binary mixtures of liquids has been studied and the behaviour of these has been compared with that of silica. It is concluded that the chemical nature of a gel markedly affects selective adsorption from binary mixtures of liquids