1 64 Analyfis of the Air. 



hydroftatical gages, in the following man- 

 ner, viz. 



In order to make an eftimate of the quan- 

 tity of Air which arofe from any body by 

 diftillation or fufion, I firfl put the matter 

 which I intended to diftil into the fmall 

 retort r (Fig. 33.) ; and then at a cemented 

 faft to it the glafs veffel a b, which was very 

 capacious at b y with a hole in the bottom. 

 I bound bladder over the cement which was 

 made of tobacco-pipe clay and bean flour, 

 well mixed with fome hair, tying over all 

 four fmall flicks, which ferved as fplinters 

 to ftrengthen the joint 5 fometimes, inftead 

 of the glafs veffel a b, I made ufe of a large 

 bokhead, which had a round hole cut, with 

 a red hot iron ring at the bottom of it; 

 through which hole was put one leg of an 

 inverted fyphon, which reached up as far as 

 z. Matters being thus prepared, holding 

 the retort uppermoft, I immerfed the bolt- 

 head into a large veffel of water, to a the 

 top of the bolthead ; as the water rufhed in 

 at the bottom of the bolthead, the Air was 

 driven out through the fyphon: When the 

 bolthead was full of water to z, then I clofed 

 the outward orifice of the fyphon with the 

 end of my finger, and at the fame time drew 



the 



