• S Parthasarathy

      Articles written in Proceedings – Section A

    • Determination of ultrasonic velocity in 52 organic liquids

      S Parthasarathy

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      The paper gives determinations of ultrasonic velocities at 7·32 × 106 cycles for 52 organic liquids and water by the method of diffraction of light by ultrasonic waves. It is shown how the velocity depends on chemical constitution.

      Included in the paper are adiabatic compressibilities for all the liquids studied, calculated from the well-known formula.

    • Ultrasonic velocities in some organic liquids—part II

      S Parthasarathy

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      The paper contains determinations of ultrasonic velocities in 14 organic liquids, some of them being di-esters, by the method of diffraction of light by high frequency sound waves. Included are also adiabatic compressibilities for these compounds, calculated therefrom.

    • Ultrasonic velocities in liquid mixtures

      S Parthasarathy

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      The paper gives results and graphs of (a) ultrasonic velocities and (b) adiabatic compressibilities in the following four binary liquid mixtures in all of which one component is carbon tetrachloride; the second component being (1) benzene, (2) carbon disulphide, (3) ethyl acetate and (4) tetralin.

      The variation of adiabatic compressibility of the mixture was found to be not always strictly proportional to concentration. These results are applied to experimental investigations in an earlier paper of the author2 where it was observed that the intensity of scattered light in binary liquid mixtures (completely miscible and at temperatures far removed from the critical solution temperature) was not always proportional to concentration. The trend of the curve in light-scattering and compressibility studies is the same, being concave or convex towards the concentration axis in both the cases, or being straight. The agreement is satisfactory.

    • Ultrasonic velocities in some organic liquids—Part II

      S Parthasarathy

      More Details Abstract Fulltext PDF

      The paper contains determinations of ultrasonic velocities in 14 organic liquids, some of them being di-esters, by the method of diffraction of light by high frequency sound waves. Included are also adiabatic compressibilities for these compounds, calculated therefrom.

    • Ultrasonic velocities in liquid mixtures

      S Parthasarathy

      More Details Abstract Fulltext PDF

      The paper gives results and graphs of (a) ultrasonic velocities and (b) adiabatic compressibilities in the following four binary liquid mixtures in all of which one component is carbon tetrachloride; the second component being (1) benzene, (2) carbon disulphide, (3) ethyl acetate and (4) tetralin. The variation of adiabatic compressibility of the mixture was found to be not always strictly proportional to concentration. These results are applied to experimental investigations in an earlier paper of the author2 where it was observed that the intensity of scattered light in binary liquid mixtures (completely miscible and at temperatures far removed from the critical solution temperature) was not always proportional to concentration. The trend of the curve in light-scattering and compressibility studies is the same, being concave or convex towards the concentration axis in both the cases, or being straight. The agreement is satisfactory.

    • Diffraction of light by ultrasonic waves

      S Parthasarathy

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      A detailed relationship between the angle of inclination of the oscillating quartz, and the diffraction spectra produced by it at these angles, is given. It is explicable on the basis of the Raman-Nath theory for the diffraction of light by high-frequency sound waves. The paper includes the case of overlapped resonance, the resonances occurring at 7/2n and 5/2n, independent of each other.

    • Ultrasonic velocities in organic liquids - Part III. Esters and ethers

      S Parthasarathy

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      Ultrasonic velocities have been determined for a number of ethers and esters. They are correlated to chemical constitution and in general we may conclude (a)that for ethers (1) methyl and methoxy groups seem to favour greater sound velocity compared to ethyl and ethoxy groups, and (2) aromatic ethers show higher velocities than those of the aliphatic series; and (b)that for esters (1) heavier acid or alcohol radical lowers sound velocity in spite of lengthening of the chain, and (2) the introduction of a heavy atom like chlorine in the acid radical enhances the velocity, as against diminution in velocity observed in the series methylene chloride, chloroform and carbon-tetrachloride. Some points of similarity between ethers and esters, with regard to the sound velocity, are pointed out.

    • Ultrasonic velocities in organic liquids - Part IV. Halogen Compounds

      S Parthasarathy

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      The paper gives ultrasonic velocities at about 7·32 ×106 c./s., and adiabatic compressibilities calculated therefrom, in 15 halogen substituted compounds, of both aliphatic and aromatic series. It is found in general, from a consideration of the results, that (1) introduction of a heavier atom lowers acoustic velocity, and (2) the presence of a double bond—or unsaturation—favours lowering of the velocity.

    • Resonance curves for a quartz oscillator immersed in liquids

      S Parthasarathy

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      The paper gives results of investigation with regard to the resonance curves of a quartz oscillator immersed in liquids. Each curve is characteristic of the liquid and is resolved one from another very clearly only on the lower frequency region of the curve. The order of resolution observed is the order of the viscosities of the liquids. It was also noticed that a greater number of diffraction orders was observed, not at the resonance of the crystal, but at a point of lower frequency, corresponding to the region of clear resolution of the resonance curves. The effects of damping, namely (1) a shift in frequency and (2) flatness of the resonance curve are observed and recorded. The range and sharpness of resonance have been compared (a) as between different liquids of different damping co-efficients at a given frequency, and (b) in one liquid but at different frequencies (higher harmonics). For condition (a) range extends while the sharpness diminishes for highly viscous liquids, while for condition under (b) the sharpness increases with diminished range at higher frequency.

    • Diffraction of light by ultrasonic waves—part II - Reflection and Transmission Phenomena

      S Parthasarathy

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      With sound of wave-lengths 0·0651 and 0·0501 mm. in liquid, light is found to get reflected in accordance with Brillouin’s formulamλ = 2 λ* sin θ. The formula is satisfied with different values form, λ and λ*. Further, confirmation is obtained by the verification of the relation between the incident and the reflected angles, when the reflected beam moves through twice the angle of rotation of the reflecting surface. Photographs of reflection of the first, second and third orders for some prominent mercury lines are reproduced. It is made out clearly that transmission (Raman-Nath’s theory) and reflection (Brillouin’s theory) are two separate phenomena, superposed on each other, in the case of diffraction of light by high-frequency sound waves. Remarkably enough, the treatment for diffraction by both the methods leads to the same formula, which enhances the difficulty of separating out the intensities due to each cause.

    • Dispersion of acoustic velocity in organic liquids

      S Parthasarathy

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      Acoustic velocities at about 7×106 c./s. and 20×106 c./s. were determined in some hydrocarbons, one alcohol, ketones, esters, ethers, halogen substituted compounds and a base. No dispersion in velocity could be detected in any of these compounds.

    • Ultrasonic velocities in organic liquids - Part V. Some related groups

      S Parthasarathy

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      The paper gives ultrasonic velocities and adiabatic compressiblities in the following compounds: methyl cyclohexanols (o, m, p), methyl cyclohexanones (o, p), tertiary amyl alcohol, (sec.) octyl alcohol, mesitylene, diphenyl methane, dekahydronaphthalene,p-cymene, β-picoline, acetonitrile and phenyl mustard oil. The relation between sound velocities and chemical constitution is discussed.

    • Ultrasonic velocities in organic liquids - Part VI. Related compounds

      S Parthasarathy

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    • The visibility of ultrasonic waves in liquids

      S Parthasarathy

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