92 



ELEMENTARY GENERAL SCIENCE 



CHAP. 



The number of cubic centimetres in the object is also the 

 number of cubic centimetres of water displaced by the object ; and, 

 since one cubic centimetre of water weighs one gram (the weight 

 varies slightly at different temperatures, but we may disregard 

 the variation here), the number of grams which the water dis- 

 placed weighs is the same as the number of cubic centimetres 

 displaced. The experiment will show that the loss of weight of 

 an object submerged in water is equal to the weight of the water 

 displaced by the object ; or, expressed in another way, the upthruxt 

 experienced by an object immersed in water is eynal to the weight of 

 the water displaced. 



EXPT. 78. Repeat Expt. 77 with a pair of scales instead of 

 a spring balance. To do this, suspend the object by means 



F IG . 41. Determination of the Loss of Weight of a Body in Water. (But notice 

 the stopper is suspended from the icrong arm, see p. 51.) 



of a piece of thread from a hook above the left pan of a 

 balance, and weigh it. Then place a glass of water upon a 

 platform or stage so that the object is immersed as in Fig. 41, 

 and weigh again. The loss of weight will, as before, be found 

 to be equal to the weight of the volume of water displaced by 

 the object used. 



Kxi'T. 79. Using the graduated glass jar already described 

 (Expt. 43), fill it about two-thirds full of water, noticing the 

 mark level with the top of the water. Procure a cylindrical 

 tin canister about half the diameter of the jar. Place the 



