Chemistry and Physics. 143 



alkaline chlorides by the usual methods, with the precaution of 

 driving off ammonium chloride at a low temperature in a muffle, 

 he treats their solution in water with about 0-05 g. of platinic 

 chloride, evaporates to a paste, treats with a small amount of 

 hot water, filters on an asbestos filter contained in a glass tube, 

 washes with 80% alcohol, reduces in the tube by heating in 

 hydrogen, dissolves the resulting chlorides in water, evaporates 

 to a paste, takes up in four drops of concentrated hydrochloric 

 acid, filters on a tiny filter, into a flask of 2 or 3 cc. capacity, 

 washing several times with four drops of hydrochloric acid. 

 He then applies the spectroscopic method of Gooch and Phinney 

 which appeared in this Journal in 1892. He states that it is 

 desirable for the operator to remain in the dark for at least an 

 hour before making the observations. It is his opinion that an 

 accuracy within from 5 to 10 per cent is easily obtained. — Jour. 

 Indust. and Eng. Chem., 10, 50. h. l. w. 



5. Absorption Bands of Ozone. — When taken under favorable 

 conditions, photographs of the ultra-violet spectra of many 

 stars, — such as Capella, Eegulus, Sirius, and Vega, — show a 

 series of fairly narrow absorption bands near the short wave- 

 length limit set by the earth's atmosphere. Since the wave- 

 lengths of these bands as given by Huggins and Sampson do not 

 agree with the corresponding data for ozone published by 

 Ladenburg and Lehmann, and since telluric ozone seemed to 

 be the most probable cause of the occurrence of the bands in 

 stellar spectrograms, A. Fowler and R. J. Strutt have recently 

 subjected the matter to experimental investigation. 



The first part of the work consisted in making a new and care- 

 ful study of gaseous ozone artificially prepared. The ozone was 

 generated in the ordinary way by means of a Siemens ozonizer. 

 The absorption vessels were of various kinds. For great thick- 

 nesses glass tubes were used, closed by quartz plates cemented 

 on with sodium silicate. The length of these tubes varied from 

 46 cms to 244 cms. For small thicknesses the ozone stream was 

 delivered by displacement into silica flasks or test-tubes placed 

 in front of the slit of the spectrograph. This instrument was 

 furnished, of course, with a prism and lenses of crystalline 

 quartz, and it gave a dispersion of 58 A per mm. at A 3200. 

 The best source of continuous radiation in the ultra-violet was 

 found to be burning magnesium ribbon. The authors record the 

 wave-lengths of 34 distinct bands due to ozone. These bands 

 appear on the less refrangible side of the great ozone band that 

 limits the solar spectrum, and their wave-lengths extend from 

 3089-5 A to 3432-2 A. 



These data agree very well with the wave-lengths derived from 

 the stellar spectrograms. The most convincing evidence, how- 

 ever, in favor of the belief that the bands in the spectra of the 

 stars are due to ozone, is obtained by direct comparison of the 



