various Coloured Bodies on the Spectrum. 445 



9. Sulphate of Cobalt, pale pinkish-red by daylight, paler and 

 bluer than the nitrate of cobalt. It converts the blue into violet, 

 absorbing from E up to D 4, leaving that space a dark green, and 

 proving that blue rays exist at that place. The space D ; D4 

 becomes a greenish whitish band. 



At greater thicknesses the dark band F, D 4 becomes black, 

 the violet remaining quite distinct. 



10. Sulphate of Ammonia and Chromium, pale greyish blue by 

 daylight, and pink by candle-light. It has a very curious action 

 on the spectrum. It attacks it most powerfully at the violet 

 end, then at D 2 and D, till the space D, D 2 disappears, which 

 takes place before the absorption has reached E. The absorp- 

 tion advances to n, — the lines C, c, and m, particularly C, being 

 widened. At great thicknesses a green and blue band, in the 

 centre of which is F, remains, and a bright narrow band C n, 

 which is persistent. The red space is curiously acted upon. 



11. Chromate of Ammonia, an intense yellow at small, and 

 orange at great thicknesses. It begins its action at the violet 

 end, and advances almost simultaneously over the blue and gra- 

 dually up to D 2. At greater thicknesses it would doubtless 

 advance far into the red space. 



12. Sulphate of Cobalt mixed with Chromate of Ammonia has 

 nearly the same action on the spectrum as the chromate alone. 



13. Sulphate of Potash and Nickel, very pale bluish green, 

 attacks the spectrum at B, c, and m, leaving B c and cm distinct 

 bands. It attacks the violet also. 



14. Carbazotate of Potash, a brilliant intense yellow, the same 

 nearly at all thicknesses. It begins its action at the violet, and 

 absorbs gradually up to 8, leaving violet at the edge before it 

 comes to F. 



15. Red Prussiate of Potash, a fine intense yellow. The cry- 

 stals are scarlet. It has almost the same action on the spectrum 

 as carbazotate of potash. 



16. Sulphate of Potash and Copper, a pale blue. It attacks 

 the violet, and then absorbs from B to c. 



17. Bi-vanadiate of Ammonia, a pale yellow. It acts upon 

 the violet and yellow simultaneously. 



18. Chloride of Iridium and Potassium, yellow at small, and 

 scarlet homogeneous red at great thicknesses. It begins by a 

 powerful action almost simultaneously at 8 and F, when the di- 

 luted fluid is almost colourless. It then absorbs 6F. The blue 

 on the side of G towards F then disappears, leaving violet, and 

 a blue band between F and F 3. The absorption advances to b, 

 and when near E the blue disappears, and the spectrum is at- 

 tacked at D and D 2, the space between these lines disappearing, 

 and the absorption advancing on both sides destroying all the 



