Ixii GENERAL SUMMARY OF SCIENTIFIC AND 



tense, the reverse is the case in the solar spectrum. Using, however, 

 a large induction coil and battery, and then a small coil and battery, 

 Lockyer found that while in the latter case (the spectra being pho- 

 tographed) the blue line only was apparent, in the former the violet 

 lines appeared, with no trace of the blue one. Varying the inten- 

 sity of the current, a fac-simile of the three lines in the sun spectrum 

 was obtained. The author queries whether these f^icts do not teach 

 the dissociation of calcium itself, and suggests solving the problem 

 by photographing the H lines of stellar spectra. 



Delachanal and Mermet have given some results obtained by 

 means of their siDCCtro-electric tube which show its value in quali- 

 tative analysis. In the ashes of the sporules of the common puff- 

 ball {Lycojjerdon pratense), after separation of the silica, lines of so- 

 dium, calcium, magnesium, zinc, copper, and hydrogen were observed. 

 A specimen of zinc examined in this way showed the presence of 

 both indium and gallium. The estimated amount of indium in ten 

 kilogrammes of the zinc was 0.050 gramme, and of the gallium 0.002 

 gramme. 



Berthelot has re-examined the question of the rotatory power of 

 styrolene, which he had asserted, but which had been denied by 

 Yan't Hoflf. He finds that the value of (") =: 3.1 in one speci- 

 men and 3.4 in another. The difference appears to be due to the 

 presence of a little inactive styrolene. 



Wunder has investigated the absorption spectra given by light 

 reflected from different varieties of ultramarine, and gives curves 

 showing the variation of intensitv. 



Mach and Merten have studied the effect of pressure upon quartz, 

 and have shown that the velocity of light in the quartz may be 

 changed by compression, the optical elasticity being lessened in the 

 direction of the pressure, but much more in a direction perpendic- 

 ular to this. Quartz may therefore be looked upon, say the authors, 

 as an isotropic medium which has been subjected to an enormous 

 pressure during crystallization, perpendicular to the axis, thus devel- 

 oping its double refraction. 



Bosanquet has contrived a new form of polariscope, w^ith which 

 he has studied particularly the polarization of the sky. The essen- 

 tial part of the instrument consists of two quartz wedges, one of 

 Avhich is right-handed, the other left-handed. The terminal faces 

 are cut at right angles to the axis, and the inclined common surface 

 of the wedges makes an angle of about thirty degrees with the di- 

 rection of the axis, which is also the line of vision. The quartz par- 

 allelopipedon is mounted in a tube having at the eye end a Nicol 

 prism. The author claims for it certain advantages over the Savart 

 polariscope, and gives some of the results he has obtained with it in 

 studying the polarization of the sky. 



Soret and Sarazin have made a series of measurements to ascertain 



