508 P. E. Browning — Study of Flame Spectra. 



The gas is then turned on and the burner so adjusted as to give 

 a good colorless flame. Enough acid is then added through 

 the thistle tube to start a gentle evolution of carbon dioxide, 

 and this gas carries enough of the solution to be swept by the 

 current of gas into the flame. Mineral carbonates have an 

 advantage over commercial precipitated carbonates on account 

 of their freedom from sodium. This form of apparatus may 

 be used to obtain sodium, potassium and lithium flames, but 

 the apparatus designated in fig. 2 is rather better for these 

 elements. 



Fig. 2 is modelled after a type of burner used in the labora- 

 tory of .M. Urbain at the Sorbonne in Paris, where the author 

 made its acquaintance. This apparatus is constructed similarly 

 to that marked fig. 1 except that in place of the thistle tube a 

 tube is so arranged that a glass rod attached by a rubber con- 

 nector may slide up and down within it. Attached to the end 

 of the glass rod by a hook made by drawing out the glass is a 

 piece of zinc bent in shape of a tube about an inch in diameter. 

 The form here described differs from the Paris type in the sub- 

 stitution of a porcelain tube for a glass tube, not essential if 

 the burner is used only for sodium, and the tube-shaped piece 

 of zinc rather than a strip of zinc to secure a greater surface of 

 metal. 



To operate this burner a solution of a sodium, potassium or 

 lithium salt is placed in the bottle and enough acid is added to 

 give a gentle evolution of hydrogen with the zinc. The stop- 

 per is placed in position and the zinc lowered into the liquid 

 by means of the glass rod. The current of hydrogen operates 

 to bring the solution of the salt into the flame. 



