Fhdd Pressure 91 



Exercise for Student. 



Using the values found for the weight and volume of the lump 

 of marble in Experiment 29, write out fully the various steps of the 

 argument by which you consider the specific gravity of marble may 

 be obtained therefrom. 



EXPERIMENT 30. Weigh a solid body, such as the 

 glass stopper of a bottle, in air, in .water, and in another 

 liquid say paraffin oil. Note the apparent loss of 

 weight of the stopper when weighed in the water and 

 also in the paraffin. Apply the Principle of Archi- 

 medes to the problem of finding the specific gravity 

 of the paraffin oil from the measurements made. 



54. The Principle of Archimedes does not apply 

 directly to the case of bodies floating in a liquid, since 

 the weight of any such body is entirely supported by 

 the upthrust of the liquid and consequently it appears 

 to lose all its weight under these conditions, whatever 

 its volume may be. A similar principle may be 

 deduced as the result of a simple experiment. 



EXPERIMENT 3 1 . Procure a flat-bottomed tube, such 

 as is commonly used for the preservation of chemical 

 specimens, and pour into it small leaden shot in suffi- 

 cient quantity to keep it, when it is floated in water, 

 in an upright position. Cork the tube, and float it 

 thus prepared, in a vessel of water. Note carefully 

 the height to which the liquid rises on the outside of 

 the tube. Remove the tube from the water and dry 

 it. Find by calculation from the external dimensions 

 of the part of the tube which was under water, the 

 volume, and hence the weight, of water displaced by 

 the immersed portion. ( Weigh the tube and shot, and 

 compare this weight with that of the water displaced 

 by the apparatus. 



Repeat the operation with a larger quantity of shot 



