44 THE ATLANTIC. [ CHAP. I. 
The cup ¢ is now filled with strong solution of caustic potash, 
and, the level in n being still kept low, the stop-cock @ is opened 
full, and d very carefully, thus allowing caustic potash to run 
down through a into m, where it meets the gas in the most advan- 
tageous way for quick absorption. When enough caustic potash 
has been allowed to enter, d is closed, some mercury poured into 
e,and d@ again opened, when the mercury drives all the solution 
Fie. 6.—Arrangement of the Capillary Portion Fig. 7.—Arrangement of the Capillary Por- 
of the Gas-analysis Apparatus. tion of the Gas-analysis Apparatus. 
out of the capillary tube into m, and occupies its place. When 
the absorption is finished, the level of the mercury in 7 is again 
raised, and the stop-cocks 6 and ¢ opened. The stop-cock @ is 
now very carefully opened, the flow of the gas being further 
regulated by raising or depressing p, and the gas allowed to pass 
over into g until the potash solution just touches the lower 
surface of the stop-cock a, which, being open, has the position 
shown in Fig. 7. The position of @ is now changed to that 
