394 THE CHEMISTRY OF THE SUN. [CHAP. 



4454 is most strongly reversed, and remains reversed after the 

 others have disappeared. 1 



It is a significant fact that although K is sometimes reversed with- 

 out H, H is never reversed without K. In a paper read before the 

 Royal Society in 1879, Mr. Lockyer mentions a photograph which 

 exhibits the blue line of calcium at one pole and the H and K lines 

 without the blue at the other. 2 Again, in further consideration of 

 the reversal of lines observed in the flame of calcium produced in 

 the arc of a Siemens' machine it is noted by Mr. Lockyer that as 

 the vapour recedes from the arc, or in other words as it reaches 

 regions lower in temperature, the H and K lines are gradually 

 extinguished, K disappearing before H. 3 



Messrs. Liveing and Dewar's results in their lime crucibles, are 

 exactly those which Mr. Lockyer had previously obtained, and serve 

 to confirm his views. 



Bcvrium. In an arc of 25 Grove cells in a lime crucible, baryta 

 reverses 5535 (given by Thai en, as 5534). 4 



Barium chlorate in a carbon crucible in an arc of 30 cells gives 

 4553, 4933, 5518, and 5535 reversed. 5 



Charred barium tartrate in Siemens' arc in a lime crucible sup- 

 plied with hydrogen, gives the four lines already mentioned and in 

 addition the line 6496. 6 



Baryta and aluminium in the lime crucible give the same lines 

 reversed as on introducing hydrogen. 7 



Baryta and magnesium in an arc of 25 cells in the lime crucible, 

 reverses the line 5535 along with a line about 4930, which Messrs. 

 Liveing and Dewar say may probably be due to barium. 8 



The nearest barium line in Thalen's map is 4933, and in Huggins' 

 4934. 



A mixture of barium and potassium carbonates in an arc of 30 

 cells in carbon crucible, reverses 5535 and 4933. 9 



The apparent contradiction of barium chlorate, is easily explained 

 when we consider the increase of temperature and the enormous 

 volume of carbonic oxide produced when the chlorate is dropped into 



1 Proc. Eoy. Soc. vol. xxviii. p. 368, 6 Ibid. p. 473. 



2 Ibid. p. 426. See ante, p. 385. 7 Ibid. p. 473. 



3 Ibid. p. 432. fe Ibid. p. 357. 



4 Ibid. p. 357. 9 Ibid. p. 369. 



5 Ibid. p. 369. 



