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Thb ufe of this apparatus muft be obvious. The parts are all 

 to be fcrewed together as in the figure except the ftrong glafs 

 veflel and its flop cock ; the phials are alfo to be removed. The 

 jar ( b ) being placed on the Ihelf of the pneumatic tub will, in 

 thefe circumftances, contain a portion of the common air of 

 the apartment. In order to remove this, the pifton of the 

 condenfer is to be raifed ; upon v^hich the valve at ( b ) WiW 

 clofe, and that at ( f) W\\\ open and admit into the vacuum 

 formed in the barrel a portion of the common air contained 

 under the jar, and the water will rife in the jar in proportion 

 to the capacity of the barrel of the condenfer. On thrufting 

 down the pifton the valve {/) clofes, and the air is expelled 

 through the valve {h ), This operation is repeated till all the 

 common air is removed from the jar (^), and the water com- 

 pletely fills it. The ftrong glafs veflel ( /, « ) with its ftop cock 

 is now fcrewed on. It is nearly filled with the water to be im- 

 pregnated, but not quite, a fmall portion \m) of air being left 

 in order to allow room for the agitation of the water. The jar 

 (3 ) is now to be filled with carbonic acid gas, which is pumped 

 up and forced into the glafs veflel in as large a quantity as it will 

 admit without danger of burfting, which in my veflel containing 

 about a pint meafure is about an equal bulk of gas The glafs 

 veflel is then to be taken off" lits ftop cock being previoufly 

 clofed) and agitated brifls.ly ; and as the water abibrbs the gas 

 more readily when many of its particles are thus forced into 



contacfl 



