272 



Hartley — The Action of Heat on the Absorption Spectra and 



A series of photographs of spectra was taken from CoCL'GHsO in a saturated 

 solution prepared at 20° C, but heated to 53° C. and allowed to cool. Cadettand 

 Neall's Lightning Spectrum plates were used, but they gave photographs with too 

 little density. 



The thinner part of the cell was observed and the coolest solution : — 



X 



Spectrum begins at . . . . . . . 656 



Eays trausmitted to ...... 560 



But there are three Ahsor^ition Bands visible between 



X 656 and 612. 

 First hand, feeble, 

 Second band 



Third band 



Great Absorption Band 

 Rays transmitted from 

 to beyond 



656 to 642 

 642 to 627 

 627 to 612 



565 to 474 



474 

 330 



The first, second, and third bands are degraded on the less refrangible side, 

 as on Plate XVIII. 



The thicker layer of liquid examined : — 



Eays transmitted feebly from 

 to 

 Great Absorption Band 

 Eays transmitted from 

 to beyond 



The thicker part of the cell at or about 50° C. 



Spectrum begins feebly at 

 Eays transmitted to 

 Great Absorptio7i Band 

 Eays transmitted from 

 to beyond 



X 



627 

 584 

 584 to 436 

 436 

 330 



612 

 584 

 584 to 442 

 443 

 330 



The thinner layer of liquid at the lower part of the cell at 50° C. : — 



X 



Spectrum begins at 623 



and continues to ...... . 584 



There is evidence of an Absorption Band between . 623 and 620 



And another Absorption Band between . . . 620 and 612 



Great Absorption Band ...... 584 to 465 



Rays transmitted from . . . . . . 465 



to beyond ...... 330 



Cobalt Chloride, CoCL-CHaO, dissolved in absolute alcohol. — The solution 

 looked blue, but of rather a different tint to that of the hot aqueous solution ; it 

 was also more transparent. The band of red light transmitted near C was dis- 



