CHAPTER XII. 



PROPERTIES OF GASES. 



25. WEIGHT OF AIR. 



i. Air has weight. Fit up an eight ounce flask with a closely-fitting 

 rubber stopper, having a hole in ri 

 through which a short piece of glass 

 tubing passes. To this is fixed a 

 small piece of rubber tubing closed 

 with a clip. Suck out as much air as 

 possible by means of an air pump ; 

 close the clip before removing from 

 the pump and then weigh. Open the 

 clip ; air rushes in. Weigh again. 

 There is a decided increase in weight. 

 Air has weight ! 



ii. To find the weight of a litre 

 of air. Use the flask from the last 

 experiment. Put 50 c.c. of water in 



> 



FIG. 46. 



FIG. 47. 



it. Fit as shown in Fig. 47, taking care that the dip is open. Heat till 

 steam is issuing freely, and continue heating for a further five minutes ; 



6U 



