604 Scientific Intelligence. 



the values found heretofore for most liquids differed markedly 

 from 2. A similar computation for nitrogen led to the numerical 

 result u — 2'12±0'02, and to the conclusion that the molecules 

 of this element act as if they were approximately spherical in 

 shape. Further experimental work to remove any doubt about 

 the legitimacy of the extrapolated data is said to be in progress. 

 — Ann. d. Physik, vol. xlvi, p. 419, Feb. 1915. h. s. u. 



5. The Absorption Spectrum of Chlorophyll. — Since the 

 results obtained by earlier investigators have not been fully con- 

 cordant and since the wave-lengths used have not exceeded 2/x the 

 problem has been taken up anew by D. van Gulik. Further- 

 more, Willstatter and Stoll have succeeded in separating the two 

 components, " a " and " £," of chlorophyll and in making pure 

 preparations of each constituent. The former furnished van Gulik 

 with the material studied. In order to transmit the heat waves 

 very pure carbon bisulphide was used as solvent. The radiations 

 were emitted by a Nernst glower and spectrally dispersed by a 

 quartz prism. The values of the absorption coefficient a, as 

 defined by the equation T = I.10~ ad , were determined for wave- 

 lengths lying between the limits 576/x/x and 3'6/x. 



The a component has an intense absorption band in the red 

 with its maximum at 0'65/x. Weak absorption continues into the 

 infra-red and a relatively weak secondary maximum falls between 

 0-8/x, and 0'% The b component has a strong maximum at 

 0-63/x, with a weaker companion band on the more refrangible 

 side. This constituent of chlorophyll, however, exerts practically 

 no absorption from 0*8/x to 0'9/x. From 1/x to 3/x neither com- 

 ponent shows appreciable absorption. At 3"3/x a double band of 

 absorption sets in, for both the a and b preparations, and extends 

 to about 3*55/x. The principal maximum has the wave-length 3'4/a 

 and the secondary, 3 - 5/>t. In this region the absorption curves of 

 the two components are very similar in shape and intensity. 

 The bands in the visible spectrum have been investigated very 

 often in the past, but the doublet at 3*4^ is new. The author of 

 the original paper is in doubt concerning the physiological signi- 

 ficance to plant life of the infra-red bands. Although the solar 

 radiation, as transmitted by the earth's atmosphere, may be suffi- 

 ciently intense to influence vegetation, the water in the plant 

 cells may prevent the radiation from penetrating as far as the 

 region occupied by the chlorophyll particles. — Ann. d. Physik, 

 vol. xlvi, p. 147, Dec. 1914. h. s. u. 



6. A New Type of Band Series. — In the year 1913 two 

 accounts of the same band spectrum were published almost 

 simultaneously by W. E. Curtis and E. Goldstein, working in- 

 dependently and in different countries. The former found that 

 the spectrum was best developed, in the wider parts of the tubes, 

 when an electric discharge, with small capacity and a short air- 

 gap, was passed through helium at a pressure somewhat higher 

 than that which is usual in sealed tubes of the gas. It is not 

 certain, however, that the spectrum is due to helium because 



