COOLING LIQUIDS. STEAM. 235 



his red-hot iron in a tank of water, the 

 water which surrounds the red-hot iron 

 is made boiling hot, but the water below 

 the surface remains quite cold. 



Q. If you wish to COOL LIQUIDS, where should 

 tJie cold be applied ? 



A. To the top of the liquid ; because 

 the cold portion will always descend, and 

 allow the warmer parts to come in 

 contact with the cooling substance. 



Q. Does BOILING water get hotter by being 

 KEPT on the FI RE ? 



A. No; not if the steam be suffered 

 to escape. 



Q. WHY does not boiling water get HOTTER, 

 if the steam be suffered to ESCAPE ? 



A. Because as fast as the water boils, 

 it is converted into steam; and the 

 steam carries away the additional heat, 

 as fast as it is communicated. 



Q. Is STEAM visible or INVISIBLE ? 



A. Steam is invisible; but when it 

 comes in contact with the air (being 

 condensed into small drops) it instantly 

 becomes visible. 



Q.. How do you know that STEAM is INVISI 

 BLE? 



