Chemistry and Physics. 477 



A recent investigation by R. V. Raman has led him to the 

 conclusion that the color of the sea is due to the scattering of 

 light by the water molecules alone. The Rayleigh law of scatter- 

 ing for gas molescules cannot be applied directly to the case of a 

 liquid where the spacing of the molecules is so close and the free- 

 dom of movement must be small. A method of attack has how- 

 ever been found in the "theory of fluctuations" proposed by 

 Einstein and Smoluchowski who consider that a liquid medium 

 may be regarded as undergoing small local variations of density 

 due to the irregular movements of the molecules and that as a 

 result of these fluctuations of density, light is scattered. 

 Raman's calculations from this theory show good agreement 

 with the observed intensity of light scattered by pure water. It 

 is not far from 160 times that in dust free air. 



Other observations which confirm the author's new view are 

 that: (a) the coefficient of extinction agrees well with the theo- 

 retical value in the parts of the spectrum where there is no 

 selective absorption; (b) a sufficiently deep layer of water is 

 shown to exhibit by molecular scattering a deep blue color inde- 

 pendent of reflected sky light; (c) apart from the fact that the 

 bluest waters are highly transparent and markedly free from 

 colloidal matter, a discussion of the effects of suspended matter 

 shows that the observed results are hardly consistent with the 

 assumption of its presence; (d) a number of interesting 

 phenomena of polarization and scattering are satisfactorily 

 explained. — Proc. Roy. Soc. 101, 64, 1922. f. e. b. 



7. Proportionality of Mass and Weight. — In the Proceedings 

 Am. Phil. Soc. 60, 1921, Charles F. Brush published a kinetic 

 theory of gravitation and the results of certain experiments 

 which were thought to corroborate it. The author's view was 

 that gravitation was due to an energy flux in the ether and on 

 this hypothesis it was thought that the very minute negative 

 permeability (sic) of diamagnetic substances might offer some 

 appreciable obstacle to this flux and thus affect the gravitational 

 field behind them. 



To test it three sets of experiments were tried. (1) A repeti- 

 tion of the Cavendish experiment with the apparatus of Boys 

 comparing the attraction of masses of aluminium, zinc, tin, lead, 

 silver and bismuth on a small silver ball. (2) Comparison of 

 the periods of two similar gravity pendulums, one having a zinc 

 bob and the other a bismuth bob. (3) Comparison of two similar 

 torsion pendulums each loaded with equal masses of zinc and bis- 

 muth. In (1) the attraction of bismuth was reported to be less 

 than that of zinc in the ratio of 72 to 100. In (2) the bismuth 

 pendulum was said to show a gain of about one oscillation in 

 35,000 over the zinc. In (3) the bismuth period was found to be 

 the shorter by 1 part in 1333. 

 - The experiment on the gravitational pendulum has recently 



