370 



CARBONIC ACID. 



(j.) The absorption of this gas by water, is slow if merely stand- 

 ing over it, but rapid, if agitated with the water in a bottle. 



(k.) Noo^s apparatus is an elegant one for impregnating water 

 with this gas ; it combines agitation and moderate pressure. 



A, The pedestal and containing vessel for the 

 marble powder and acid ; , an orifice for pouring 

 in the diluted acid which should be mixed previ- 

 ously with water and allowed to cool. 



B, The neck of the vessel to contain the water 

 which is to be impregnated ; this neck contains a 

 glass cylinder pierced longitudinally with capillary 

 ducts, and also a plano-convex lens, which oper- 

 ates as a valve. 



D, The containing vessel furnished with a stop 

 cock at C. 



E, A vessel of retreat for the water. As the 

 gas rises into the middle vessel, it causes the fluid, 

 by means of the bent tube e, to mount into E, thus 

 producing hydrostatic pressure, and favoring the 

 combination of the water with the gas. 



Much more powerful instruments are known in 

 the arts.* The following is from Dr. Hare. 



IMPREGNATION OF WATER WITH CARBONIC ACID. 



" A condenser, A, is fastened at bottom, into a block of brass, 

 which is furnished with a conical brass screw, by means ol which, it 



Phil. Trans. 1803; Dr. Henry's Apparatus. 



