72 Domestic Science 



outside of the flask and mark on it the position of the 

 upper surface of the liquid when the flask is standing 

 in an upright position on the bench. Note the shape 

 of the water occupying the lower part of the flask and 

 the position of its free surface with respect to that of 

 the Earth. Weigh the flask and its contents. Turn 

 the flask so that it rests on its side instead of on its 

 base. Note again the shape of the water and the 

 position in which its free surface settles. Test whether 

 any change in mass has accompanied the change in 

 position of the flask. Replace the flask in the upright 

 position and note whether the level of the water- 

 surface has varied with reference to the mark on the 

 gummed strip. Keep the flask and its contents 

 securely corked for a week and again examine the 

 position of the water-level and redetermine the mass 

 of the flask and contained water. 



As a result of the above investigation, we shall be 

 led to the conclusions that a liquid has a definite mass ; 

 that its volume does not vary when no external force 

 is applied and the temperature is constant, but that its 

 shape varies readily under the action of a force, i.e. 

 a given mass of liquid has no definite shape of its own, 

 but takes that of the portion of the vessel containing it. 

 Further, its upper surface, if free (i.e. not in contact 

 with the interior of the vessel), is always parallel to 

 that of the Earth, or, in other words, lies in a hori- 

 zontal plane 1 . 



Exercise for Student. 



What was the force which caused the water to change its shape 

 when the flask was tilted ? 



1 I.e. except for the meniscus referred to above and the related con- 

 vexity of surface when the containing vessel cannot be wetted. 



