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JUNIOR GRADE SCIENCE 



27. BOYLE'S LAW. 



i. Relation between pressure and volume of gases. (a) Select a glass 

 tube about 20 cm. long, and neatly closed at one end (Fig. 53, A). Tie 

 a piece of stout india-rubber tubing about a metre long upon the open end 



FIG. 53. Two forms of apparatus to show the relation between the pressure 

 and volume of a gas. 



of the tube, and fix the other end of the tubing upon a glass tube B, about 

 20 cm. long, open at both ends. Now carefully fill the tubes with mercury 

 until the level of the liquid is about 10 cm. from the open end. Afterwards 

 fix the closed tube upright in a retort stand with the sealed end upwards, 

 place your finger upon the open end of the other tube, and lower the open 

 end so as to make the air pass into the closed tube. This apparatus will 

 enable you to measure the expansion and compression of air. 



Support the tube B with its open end upwards, and at such a height 



