Proceedings of the Indian Academy of Sciences - Section A

Prakash, Satya; Rai, Ram

doi: 10.1007/BF03046506pmid: N/A

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.

Asundi, R.

doi: 10.1007/BF03046507pmid: N/A

Pasricha, B.

doi: 10.1007/BF03046508pmid: N/A

Malurkar, S.

doi: 10.1007/BF03046509pmid: N/A

The development of a thunderstorm which is essentially a convective phenomenon needs a cause for initial convection and then conditions for its maintenance once started. The possibility of the inherent instability due to potentially colder air superposed on potentially warmer air or the analogous case of extra injection of moisture in the lower layers in shown to be not applicable in nature and that causes for initial convection must be found elsewhere than in the potential density distribution. Some of the causes are non-horizontality of surfaces of equal temperature and equal humidity; and gradient of wind velocity. It is shown that upward rise of air produced by unequal heating of the ground, does not stop where the rising mass of air attains a density equal to that of the environment (hydrostatic equilibrium), but continues to rise higher till the momentum developed is reduced to zero. The extent of over-shooting is nearly of the same order as the height between the initial level and the level of hydrostatic equilibrium. Once the condensation level is reached, it is well known that the convection will become regenerative due to the evolution of the latent heat of condensation. In the usual treatment of the problem, the ascending parcel of air is expected to condense at or before it reaches the level of hydrostatic equilibrium if it is to develop into a thunderstorm. The dynamical treatment outlined in this paper takes into consideration the overshooting of the parcel of air and thereby allows much drier air to reach condensation and thereafter maintain convection: and can thus account for a larger number of thunderstorms.

Kartha, A.; Menon, K.

doi: 10.1007/BF03046510pmid: N/A

The action of grignard reagents on methoxy methyl umbelliferone and α-naphtho coumarin was investigated to prepare compounds similar to certain naturally occurring benzopyrans.

Desai, T.; Guruswamy, S.

doi: 10.1007/BF03046511pmid: N/A

Wu, Ta-You

doi: 10.1007/BF03046512pmid: N/A

It is shown that the main features in the selective emission spectra of the night sky and the aurora, namely, the forbidden [OI] lines, the various systems of bands of N2 + and N2 and O2, and in particular, the enhancement of certain lines and bands relative to others and the diurnal variations of the intensity of certain lines in the night sky, can be satisfactorily explained on the view that all the excitation and quenching processes in the upper atmosphere are collisions of the second kind, of the resonance type, between the metastable atoms and molecules of nitrogen and oxygen. The metastable atoms are generated in the night by collisions between the metastable molecules; the latter are in turn formed by the recombinations of the normal atoms which are produced by photo-dissociation of the molecules during the day. A strong argument for the theory is that, not only the observed radiations are provided with reasonable excitation processes, but the absence of other atomic lines N, O, H and the rare gases is automatically accounted for by maximum energy available for the excitations in these metastables, which is only 6·1 volts (the energy of N2 [A3Σ]). It is suggested that these processes in Table II are the microscopic processes responsible for the observed spectra, while such large-scale features as the shapes of the aurorae and seasonal variations in the intensities, etc., may have to be explained by further hypotheses.

Ramachandran, G.

doi: 10.1007/BF03046513pmid: N/A

A theory of the optical phenomena exhibited by chromatic emulsions as also those observed in the Christiansen experiment, has been worked out,de novo, on the basis of the diffraction of light by a sphere immersed in a medium of nearly the same refractive index. Expressions are derived both for the intensity of the transmitted light, and of the light diffracted in other directions. These are discussed in relation to the intensity and the spectral nature of the light and it is shown that the theory can satisfactorily account for the various phenomena observed by Sethi and Sogani.