270 



Hartley — The Action of Heat on the Absorption Spectra and 



very questionable whether any value can be attached to measurements carried 

 beyond three figures, unless perhaps in the bands of didymium salts, vphich are 

 strong and well defined. 



Hence the measurements of the cobalt spectra are recorded to three figures 

 only. Absorption bands which are diffuse cannot be accurately measured with 

 great dispersion. 



The Spectra of Cobalt Salts. 



CoCl2*6H20. — A saturated Aqueous Solution at 20° C. 



Thin wedge cell, measurements taken at the middle of the cell. 



No. 1 :— A 



Spectrum begins at 656 



Rays transmitted from 656 to . . . . . 572 



Absorption Band . 572 to 474 



Rays transmitted from 474 to . . . . . 342 

 End of spectrum. 



Photograph 



At the upper part of the cell : — 



Spectrum begins at . 



Eays transmitted from 649 to 



Absorption Band 



Eays transmitted from 443 to 



End of spectrum. 



649 



612 



612 to 443 



372 



CoCL'CHaO. — Saturated Aqueous Solution at 20° C. 

 Measurements taken at the middle of the cell. Photograph No. 2 : — 



Complete absorption up to where spectrum begins 

 Absorption Band ...... 



Absorption Band, witb strongest side towards \ 627, 

 Absorption Band, with its strongest side at X 612, 

 Rays transmitted strongly to . 

 Great Absorption Band ..... 



Rays transmitted from 450 to . 



Measurements taken at the upper part of the cell : — 



Rays feebly transmitted from 



Spectrum extends to . 



Absorption Band .... 



Rays transmitted from X 612 to 



Indications of an absorption baud with its centre at 



Absorption Band .... 



Rays feebly transmitted to 



Great Absorptioti Band 



Rays transmitted from X 436 to 



X 



653 

 653 to 642 

 642 to 627 

 627 to 612 



584 

 580 to 450 



347 



627 



620 

 620 to 612 



602 



608 

 601 to 597 



589 

 589 to 436 



356 



