PHYSICS. 485 



ical or chemical properties. He gives the wave-lengths of eleven ozone 

 bauds, the strongest being the two near D, of wave-lengths 609.5-593.5 

 and 577-560 respectively. He finds these bands also iu the spectrum 

 of liquid ozone. He discusses the question of telluric lines in the solar 

 spectrum, and regards the blue color of the sky as due, in part at least, 

 to the presence of ozone. (J. Phys.., i^Tovember, II, i, p. 494.) 



Ciniician has carefully examined the spectrum of acetylene and finds 

 that it diiiers from that of hj'drogen much more than do the spectra 

 of ethylene and marsh gas. In these the characteristic carbon bands 

 show the spectrum to be that of a hydrocarbon gas; while in that of 

 acetylene the red, orange, and yellow portions resemble much more 

 closely the spectrum of carbon dioxide than of hydrogen. ( Wied. Ann.j 

 No. 10; V; Nature, January, xxv, p. 290.) 



Liveiug and Dewar have continued their researches on the spectrum 

 of carbon, and in a paper presented to the Royal Society give the wave- 

 lengths of twenty ultra-violet lines measured photographically by means 

 of a Rutherford grating. In studying the spectrum of a Swan incan- 

 descent lamp, they came to the conclusion that the temperature of the 

 incandescent thread heated by fifty Grove cells is not far different from 

 that of sodium heated in a cyanogen flame burning in air, but is less 

 than that of an oxyhydrogen flame. {Proc. Boy. Soc, March 9 ; Nature^ 

 April, xxv, p. 545.) 



Thollon has published in parallel columns the wave-lengths of the 

 bands of the carbon spectrum as observed by Bigourdau in the arc of 

 the electric lamp of Jamiu, by Salet in the condensed spark in cyanogen 

 or illuminating gas, by Lecoq de Boisbaudran iu the blue flame of illu- 

 minating gas, and by himself in the spectrum of comet &, 1881. (Ann, 

 Chim. Phys., February, V, xxv, p. 287.) 



Abney has published minute directions for performing work in the 

 infra-red region of the spectrum, including the preparation of the silver 

 bromide emulsion, and the method of development. {Nature, Novem- 

 ber, XXVII, p. 15.) 



Johnson has quoted Wollastou's paper in the Philosophical Transac- 

 tions for 1802, and Newton's "Opticks," 1704, in proof of his assertion 

 that Newton did employ a slit and did obtain a pure spectrum. Woll- 

 aston says: "If a beam of daylight be admitted into a dark room by a 

 crevice l-2Qth of an inch broad and received by the eye at a distance of 

 10 or 12 feet through a prism of flint glass, /rcc/rom veins, held near the 

 eye, the beam is seen to be separated into the four following colors only: 

 red, yellowish-green, blue, and violet." Newton says: "Instead of the 

 circular hole, 'tis better to substitute an oblong hole, shaped like a long 

 parallelogram, with its length parallel to the prism. For if this hole 

 be an inch or two long and but a tenth or twentieth part of an inch 

 broad or narrower, the light of the image will be as simple as before, 

 or simpler, and the image will become much broader and therefore more 



