FEBBtTAEY 5, 1904.] 



SCIENCE. 



209 



of water at a temperature of T^ be passed 

 througli a worm immersed in a steam bath 

 and energies at a temperature T,, the 

 quantity of heat absorbed is mS{T^ — Ti) 

 where m is the mass of water passed 

 through and 8 the mean specific heat of 

 water between T, and T,. If the heat ab- 

 sorbed by the water is obtained by direct 

 condensation of steam alone we have the 

 equation 



when M is the mass of the condensed 

 water and i the latent heat of condensation 

 of steam. If either L or S is taken as 

 known the other may be readily obtained. 

 Barnes 's vahies of 8 were taken and a num- 

 ber of determinations of L made to test the 

 efficiency of the method. In the practical 

 development of the method, the process was 

 made continuous. The water in the worm 

 and the condensed water were drawn oft: 

 constantly and measured. Eadiation and 

 conduction entered as important factors in 

 the construction of the calorimeter, but 

 were eliminated or a least satisfactorily ac- 

 counted for in the amount of condensed 

 water by both theory and practice. Re- 

 sults were obtained in consecutive experi- 

 ments which were concordant to the fifth 

 significant figure. The value of L which 

 was obtained was slightly lower than Cal- 

 lendar's value of 540.2 calorics at 20° C. 

 and points to the existence of a slight con- 

 stant error. 



On the Thickness of Adsorbed Aqueous 

 Films: L. J. Beiggs and A. W. McCall, 

 United States Department of Agricul- 

 ture. 



Parks {Phil. Mag., May, 1903) found 

 the thickness of the aqueous film adsorbed 

 on the surface of glass wool to be 13.6 X 

 10"'' cm. He also calculated the thickness 

 of the film on silica by an indirect method 

 based upon Martini's calorimetric measure- 



ments, and obtained the value 44 X 10^^ 

 cm. 



The authors have measured the thick- 

 ness of the aqueous film on glass wool, silica 

 and quartz when exposed at 30° C. to an 

 atmosphere five sixths saturated. The sub- 

 stances were kept at constant temperature 

 in a thermostat, and were continually 

 stirred so as to bring the material into thor- 

 ough contact with the water vapor. The 

 amount of water taken up was determined 

 by drying at 110° C. The surface area 

 was calculated from microscopic measure- 

 ments. The following values for the thick- 

 ness of the film were obtained, based upon 

 the assumption that the density of the ad- 

 sorbed layer is the same as that of the 

 liquid in mass. 



Silica 167 X 10-« era. 



Glass 18 X 10-" cm. 



Quartz 0.45 X 10-= cm. 



The great discrepancy in the results ob- 

 tained for silica and quartz indicates that 

 in the case of silica we have something 

 analogous to a solid solution — a conclusion 

 supported by the results of Bellati and 

 Finazzi. It is not improbable that in the 

 case of glass also there is something more 

 than simple adsorption, and that the meas- 

 urements with quartz give more nearly the 

 true value of the thickness of the adsorp- 

 tion film. 



The Circulation of the Atmosphere, as in- 

 dicated by the Eecent Abnormal 8ky 

 Colors: A. Lawrence Rotch, Blue Hill 

 Meteorological Observatory. 

 The author urges upon physicists and 

 others in various parts of the world the 

 importance of recording the dates when un- 

 usually brilliant sunset glows and the red- 

 dish corona around the sun, known as 

 Bishop's rings, are visible, as has been the 

 case intermittently during the past year. 

 These phenomena are probably caused by 

 discontinuous clouds of volcanic dust in 



