I92 Defcnptlon and life of C. Guy ion's EuJionietef* 

 taining the matters introduced into it. The extremity of 

 the neck is ground with emery to fit air-tight at C into the 

 glafs tube C D, open at both ends, and 20 or 25 centimetres 

 in length. F is a cylindric vefTel— a common glafs jar, into 

 which the tube of the glafs C*D may be entirely immerfed 

 below the furface of the water. 



When you with to try any aeriform fluid in order to feparate 

 its parts, and difcover the quantity of refpirable air it contains, 

 put into the retort two or three bits of fulphure of potafh of 

 the fize of a pea ; fill it with water, taking care to incline it 

 to make all the air which might remain in the bulb pafs 

 into the neck ; flop with the finger the orifice of the retort, 

 and place it in the pneumatic tub, that the gas to be tried 

 may be introduced in the ufual manner. By inclining it 

 again, alternately in different directions, all the water may 

 be eafily difplaced, and the fulphure left remaining in the 

 bulb. 



Then place the retort vertically, and introduce the end of 

 it into the glafs tube C D, which muft ftill be under water ; 

 and place below the bulb a fmall lighted taper. To preferve 

 the retort in its pofition, a cover of wood, with an aperture for 

 its neck to pafs through, fhould be fitted to the jar. 



The firft impreffion of the heat dilates the gafeous fluid, fo 

 that it defcends almoft to the bottom of the tube, which has 

 been difpofed on purpofe to receive it, and to hinder any 

 part of it from efcaping, which would be the cafe if the tube 

 were not fufficiently long, and which would prevent the 

 diminution from being accurately determined. As foon, 

 however, as the fulphure begins to boil, the water afcends 

 with rapidity, not only in the lower tube, but alfo in the 

 neck of the retort, notwithstanding the application or even 

 augmentation of the heat. If it be vital air abfolutely pure, 

 the abforption is total. In that cafe, to prevent the vefTel 

 from burfting, which might happen were it cooled too fud- 

 denly, the afcent of the water muft be retarded, either by 

 removing the taper, or inclining the retort, which will not 



hinder 



