Chemical Constitution of Saline Solutions. 273 



tinctly visible. Heating did not affect the spectrum. When a saturated solution 

 of cobalt chloride in alcohol is allowed to crystallize without the action of heat, it 

 deposits red crystals, which are in reality the original hexahydrated salt.* 



Thin wedge-cell, sunlight, Plate XX. b, fig. 1. 



Cobalt Chloride^ CoCl2'6H20. — An aqueous solution was mixed with hydro- 

 chloric acid. Plate XX. b, fig. 2, thin wedge- cell, sunlight. The liquid was 

 indistinguishable from the alcoholic solution to the eye, except when examined in 

 very thin layers, when it had a greenish colour. 



Measurements taken. ^ 



At 20° C. . Edge of Absorption Band in the red near D, . 595 



Absorptmi Bund, 562 to 503 



End of visible spectrum, . . . . 413 



At 40° C. . Red extremity of the spectrum, . . . 724 



The band of transmitted rays measured near C, 699 



Edge of Absorption Band in the red, . . 609 



Absorption Band in the green, . . . 562 to 503 



End of visible spectrum, . . . . 416 



Cobalt Chloride, CoC]2*6H20 dissolved in glycerine. — Purplish solution, thin 

 wedge, oxyhydrogen light, Plate XXI. ^ 



At 20° C. . Spectrum begins, 724 



First Absorption Band. ..... 696 to 653 



Second Absor2)tion Band, .... 627 to 608 



Third and principal Absorption Band, fi-om 

 near D to beyond F, not exactly measurable 

 End of spectrum visible, .... 423 



At 40° C. . Spectrum begins at 741 



Eed rays only barely visible. 



Absorption Band, 724 to 680 



End of visible spectrum, .... 413 



At 100° C. . End of visible spectrum, the red rays have almost vanished. 



Cohalt Chloride, CoCls'GHaO. — An aqueous saturated solution mixed with 

 calcium chloride solution. The liquid was of the same purple hue as the solution 

 in glycerine. Plate XX. c. Thin wedge-cell, oxygen-gas light. 



The measurements were made at the following points, but the absorption bands 

 merged into each other. X 



At 20° C. . Rays transmitted from 718 



First Absorption Band, 691 to 659 



Second „ „ 627 to 604 



Third ,, ,, in the green, . . 560 to 479 



This band is not strong at 20° C. 

 End of the visible spectrum, .... 400 



* For analysis, see p. 299. 



