BUOYANCY OF WATER. O/ 



person wish to pour out the wine or water contained in them, the liquid will 

 run out through the holes cut in the jug. 



To use them with safety it is necessary to put the spout A in one's 

 mouth, and close the opening B with the finger, and then by drawing in the 

 breath, cause the water to mount to the lips by the tube which runs around 

 the jug. The specimens herein delineated have been copied from some now 

 existent in the museum of the Sevres china manufactory. 



The Buoyancy of Water is a very interesting subject, and a great deal 

 may be written respecting it. The swimmer will tell us that it is easier to 

 float in salt water than in fresh. He knows by experience how difficult it is 



Fig. 69. Vase of Tantalus. 



to sink in the sea ; and yet hundreds of people are drowned in the water, 

 which, if they permitted it to exercise its power of buoyancy, would help to 

 save life. 



The sea-water holds a considerable quantity of salt in solution, and this 

 adds to its resistance, or floating power. It is heavier than fresh water, and 

 the Dead Sea is so salt that a man cannot possibly sink in it. This means 

 that the man's body, bulk for bulk, is much lighter than the water of the 

 Dead Sea. A man will sink in fresh, or ordinary salt water if the air in his 1 

 lungs be exhausted, because without the air he is much heavier than water, 

 bulk for bulk. So if anything is weighed in water, it apparently loses in 

 weight exactly equal to its own bulk of water. 



