Letts anp Braxe—On Atmospheric Carbonic Anhydride. 451 
Transfer of the contents of one of the sealed Tubes to the Receiver 
containing the Air to be examined, and their re-transfer after absorption 
of the Carbonic Anhydride.—Method 1. A glass stop-cock A. (fig. 5) 
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Fig. 5. 
connected by thick-walled india-rubber tubing to the mercury 
reservoir B, is clamped as shown to a tall retort-stand. A short 
piece of thick-walled india-rubber tube is also attached to the 
