Chemical Constitution of Saline Solutions. 275 
At 16°, measurements were made at the red end, ’ 670, and the blue end 
d 425. 
At 70°, measurements as before at 1557 and 44381. There was nothing 
remarkable in this spectrum beyond the much greater intensity of absorption 
at the higher temperature. 
Another solution prepared in the same way as the preceding, but which had 
been kept some time and was of a dark greenish tint, was examined. 
At 16°, measurements were made at \ 592 and ) 557. 
At 70°, the only measurement possible was of transmitted rays at )565. The 
dark green tinge became indigo-blue. 
Cobalt Bromide, anhydrous, CoBr,.—This was dissolved in absolute alcohol. 
Thin wedge. 
At 20°, the only measurements possible were made at \ 585 and d 423. 
At 70°, at \ 583°8 and \ 438. An indigo-blue liquid unaltered by heating. It 
is quite evident that the blue cobalt bromide in the hydrated state, CoBr,6H,O, 
is contained in the alcoholic solution of the crystals, and that by heating the 
solution to 70° it is rendered anhydrous. 
Cobalt Sulphocyanate, Co(CNS),—An aqueous solution of a purplish blue 
colour, very dark. Thin wedge, sunlight. 
At 20°, measurements were made at \ 724 and \ 711. Spectrum terminates at 
d 432. 
At 100°, the solution was quite opaque at this temperature. 
Cobalt Lodide, Col,6H,0.—A cold aqueous saturated solution of the brown 
hexagonal crystals. ‘The solution is brown at 16°; below this temperature some 
of the substance crystallizes out, and the liquid becomes red. 
The solid salt dissolved in about one-sixth of its weight of water, correspond- 
ing to four molecules of water to one of salt, or 16-227 grs. dissolved in 2°675 grs. 
of water at 16°, forming one of the densest saline solutions known; its specific 
gravity at 21° C. being 2°0817. Thin wedge, gas-light. 
At 20°, a very little light, transmitted at \ 627 and 536. 
At 50°, a little light transmitted at \ 588. 
On mixing with water, a red solution isformed. Thin wedge, gas-light. 
From 20° to 40°, the rays were transmitted from \ 565 to 557. 
At 100°, the rays transmitted were from \ 563 to 560. The red solution is so 
diluted that heating to 100° is almost without effect upon it. 
Cobalt Iodide. Green dihydrate, Col,°2H,0.—A cold saturated aqueous 
solution is of a very dark brownish green tint. Dilution with water, or 
absorption of moisture turns it red and of a much lighter shade. 
At 20°, a very little light transmitted at \ 588. 
