224 Scientific Intelligence. 



frequency of these molecules would be represented by the expres- 



v 

 sion n=.^— ^ in which v is the velocity of light and A the wave- 

 length of the absorption line. Consequently, whenever A is in- 

 creased by the displacement of the line toward the red, n will de- 

 crease and vice versa. Hence when a methyl, ethyl, methoxyl 

 or carboxyl group, or bromine, is introduced into a molecule in 

 place of hydrogen, its period of vibration increases, while when an 

 amido or nitro group is so introduced, the period diminishes. — 

 Zeitschr. Physikal. Chem., ii, 312-33*7; J. Chem. Soc. liv, 1141, 

 November, 1888. G. f. b. 



5. On the Absorption- Spectrum of Oxygen. — Liveing and Dew- 

 ae have examined the absorption spectrum of oxygen at high 

 pressures. The apparatus consisted of a steel tube, 165 cm. long, 

 fitted with gun-metal ends carrying quartz plates and capable of 

 sustaining a pressure of 260 or more atmospheres. At or near its 

 middle point this tube contained a quartz lens of 46 cm. focal 

 length ; so that, when a source of light was placed 1 cm. from 

 one end of the tube, an image of it was formed on the slit of a 

 spectroscope at about the same distance from the other end. On 

 admitting oxygen into the tube until the pressure reached 85 at- 

 mospheres, and using an arc-light as the source, the authors ob- 

 served : (l) a very dark band in the position of A of the sun 

 spectrum, sharply defined on its more refrangible side and divided 

 by a sti'eak of light ; (2) a precisely similar but much weaker 

 band in the position of the solar band B ; (3) a dark band diffuse 

 on both edges, extending from A 636o to X 6225, its maximum in- 

 tensity being at X 6305 ; (4) a still darker baud a little above D, 

 beginning with a diffuse edge at about X 5810, rapidly coming to 

 maximum intensity at about X 5785, gradually fading out and 

 disappearing at X 5675 ; (5) a faint narrow band in the green at 

 A 5350 ; and (6) a strong band in the blue, extending from 

 A 4795 to A 4750, and diffuse on both sides. By means of photo- 

 graphs it was shown that the oxygen was quite transparent for 

 violet and ultra-violet rays up to A 2745, then gradually diminish- 

 ing until at A 2664 it was wholly absorbed. Upon increasing the 

 pressure to 140 atmospheres, all the bands were strengthened, but 

 only one new one apjDeared, a faint one at A 4470 in the indigo. 

 By using a higher dispersion, none of these bands (which appear 

 to be identical with the terrestrial bands observed by Angstrom 

 in the sun spectrum) were resolvable into lines. Subsequently a 

 steel tube 18 meters long was employed, which at 90 atmospheres 

 contained a mass of oxygen about equal to that of a vertical col- 

 umn of the atmosphere of the same section ; but the intensity of 

 the bands produced by the compressed gas was far greater than 

 that of the corresponding bands in the solar spectrum with a low 

 sun. — Phil. Mag., V, xxvi, 286, September, 1S88. G. f. b. 



6. On the Spectrum of Oxygen at high altitudes. — Janssen 

 has observed the solar spectrum at the Grands Mulets station on 

 Mt. Blanc at an altitude of 3000 meters and has proved that the 



