• Satya Prakash

      Articles written in Proceedings – Section A

    • On non-spherical nature of colloidal particles in relation to the formation of Jelly structure

      Satya Prakash

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      The magnetic birefringence of mercuri-sulphosalicylic acid sol has been studied in detail. The fresh sol directly obtained by dissolving mercuric oxide in sulphosalicylic acid is non-birefringent, but the reversible dried powder when dispersed in water gives birefringent sol. The birefringence increases as the magnetic field increases but not in the same proportion as in the case of nitrobenzene. The birefringence is also almost directly proportional to the concentration. In presence of dissolving ions, as chloride, the birefringence markedly diminishes, while in presence of nitrate ions or barium ions, it increases. The influence of peptisers and sensitisers as sugar, glycerine, ethyl alcohol, acetone and urea has also been investigated. With the exception of urea which does not produce any marked effect, in all other cases, the birefringence values decrease. With alcohol and acetone the fall is much marked. These results have been discussed and it has been shown that in their presence the anisotropy of the particles is decreased on account of disintegration of bigger aggregates to isotropic smaller ones and also due to the formation of spherical micelles by adsorbing layers of organic solutions round the originally anisotropic particles.

      It has been shown that many of the well-known jelly-forming sols do not exhibit magnetic birefringence, and hence, it is not necessary to have non-spherical particles essential for jelly formation. On the contrary, it is also likely that the non-spherical lyophobic particles also become isotropic by becoming hydrated under favourable conditions.

    • Kinetics of sol-gel transformation - Part III. The influence of temperature on the setting of some inorganic jellies

      Hira Lal Dube Satya Prakash

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      In continuation with the previous work, the authors have studied the kinetics of sol-gel transformation with reference to the concentration of the coagulating electrolyte. Differently prepared samples of ferric phosphate show that in every case where a jelly is formed, the equation log S = log R +p log C is applicable during the period of slow gelation, where S is the rate of jelly formation, C the concentration of electrolyte,p the jelly-characteristic, and R the rate constant. The authors have studied the influence of temperature on the rate of setting of ferric arsenate, ferric phosphate, aluminium hydroxide and zirconium hydroxide jellies, and they have found that the value of R increases as the temperature is increased, whereas, the value ofp shows only a very slight decrease. It is expected that so long as the jelly is not characteristically changed in texture, the value ofp ought to remain constant, but in most cases, the texture also undergoes some variation as the temperature is increased (the jelly becomes opalescent and more synerising), the constantp slightly decreases.

    • Kinetics of sol-gel transformation - Part V. The influence of different coagulating electrolytes on the setting of ferric phosphate gel

      Hira Lal Dube Satya Prakash

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      In continuation with the previous work, the authors have studied the influence of different coagulating ions on the setting of ferric phosphate jellies. The values ofp, the jelly characteristic and R the rate constant in the equation log S-log R+p log C do not change much with uni-univalent electrolytes. The slight variations with chloride, bromide and nitrate ions are due to the different adsorbabilities of these ions by ferric phosphate. When the jelly formation is affected with uni-polyvalent ions the marked variations are observed consistent with Whetham’s law, or any other generalized expression. With poly-univalent electrolytes, the values ofp and log R do not markedly change as the sol itself is positively charged.

      In the end, the authors are grateful to Prof. N. R. Dhar for his interest throughout the work.

    • Studies in blue perchromic acid - Part I—Kinetics of the Decomposition of the blue perchromic acid in various organic media

      Satya Prakash Ram Chandra Rai

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      The decomposition kinetics of the blue perchromic acid was studied under various conditions. The decomposition reaction is monomolecular. The value of K at 10° is 0·002125, at 20° 0·005273 and at 30° 0·0171 to 0·02241. The values differ slightly with different preparations. The values of log K plotted against 1/T give straight line, showing that Arrhenius equation is valid. From the study of kinetics, we find that there is a marked induction period also.

      The rate of decomposition of the blue acid is markedly increased in the presence of benzene, toluene and xylene. When these hydrocarbons are present to the extent of 33 per cent. of the ethereal solution, the values of K increase 1·79 times with benzene, 2·57 times with toluene and 3·28 times with xylene, when the temperature maintained is 30°.

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