Chemistry and Physics. 243 



methods, which are fully described in Lecher's paper. The fol- 

 lowing table gives the results : 



Time of 



Mirror glass. 



Solin glass. 



T\\ £»1 Gotvio prtnctoTitc — , 



charging 1 

 in seconds. 



Rubber. Petroleum. Water. 





0-8797 cm! 



0-4338 cm 



. 0-7164 cm. 1-9272 cm. 1-9342 cm. 



0-5 



4-67 



4-64 



2*64 Not measured. 



0-0005 



5'34 



5-09 



2-81 235 oo 



0-00000003 



7-31 



6-50 



3-01 242 oo 



These results show a marked increase in the constant when it 

 is measured by the quick method of oscillation. The author dis- 

 cusses the cause of this variation and points out that Hertz's 

 phenomenon is so complicated that slower methods of charging are 

 likely to give better results in determinations of the dielectric 

 constants. — Ann. der Physik, No. 1, 1891, pp. 142-153. J. t. 



9. Limit of Solar Spectrum in the Ultra Violet. — Dr. O. 

 Simony has obtained photographs of the solar spectrum on the top 

 of the Peak of Teneriffe and also at Courtenay. The following 

 results were obtained : 



Photographs Altitude Wave length 



obtained at in meters. Last trace. Beginning of end. 



Teneriffe 3700 292-2 293*7 



Courtenay 170 284-8 298-0 



— Comptes Rendus, Dec. 22, 1890. j. t. 



10. Recent progress in Spectrum Analysis. In the Johns 

 Hopkins University Circular for Feb., 1891, Prof. H. A. Rowland 

 gives an account of recent work done at Baltimore in the study 

 of the spectra of the various elements and the identification of 

 the lines in the solar spectrum. The spectra of all the known 

 elements, with the exception of a few gaseous ones or those too 

 rare to be obtained (see list below), have been photographed in 

 connection with the solar spectrum, from the extreme ultra violet 

 to the D line, and eye observations have been made to the limit 

 of the solar spectrum. In connection with this work, the spec- 

 tra of some of the elements have been drawn on a large scale for 

 publication, and the greater part of the lines in the map of the 

 solar spectrum have been identified. The following table, from 

 the author's observations, gives the elements in the sun, arranged 

 first according to intensity and second according to number of 

 lines in the solar spectrum. Lists of doubtful elements, those not 

 identified and finally those which have not yet been tried are 

 given also. 



Of the solar elements, attention is called to silicon, vanadium, 

 scandium, yttrium, zirconium, glucinum, germanium, erbium as 

 possibly new. Silicon has lines at wave lengths 3905*7, 4103*1, 

 5108-1, 5772*3 and 5948*7. That at 3905*7 ^is the largest and 

 most certain ; that at 4103*1 is claimed also by manganese. 



These tables are regarded as preliminary only, especially the 

 order in the first portion. However, being made with such a 

 powerful instrument and with such care in the determination of 

 impurities, they must still have a weight superior to most others 



Am. Jouh. Sci.— Third Series, Yol. XLI, No. 243.— March, 1891. 

 16 



