78 FIRST YEAR COURSE IN GENERAL SCIENCE 



water from 15 C. to 25 C. requires 10 calories; to warm 

 50 grams of water from 30 C. to 100 C. requires 50 X 70 

 or 3,500 calories. A body in cooling gives out heat. A 

 gram of water in cooling one degree' Centigrade gives out 

 one calorie. 



83. The Quantity of Heat Absorbed by Water. If 

 equal weights of water, copper, and mercury are warmed 

 through the same number of degrees, very unlike amounts of 

 heat energy are required. The quantity of heat required to 

 raise the temperature of a pound of water one degree will 

 warm a pound of copper ten degrees or a pound of mercury 

 about thirty degrees. That is, one tenth as many calories 

 are required to warm a pound of copper one degree, and one 

 thirtieth as many to warm a pound of mercury one degree, 

 as to warm a pound of water a single degree. No solid, 

 and no other liquid, absorbs so much heat in a given rise 

 of temperature as water does. (LABORATORY MANUAL, 

 Exercise XI.) 



84. Influence of Bodies of Water upon Climate. 

 Water has a much greater quantity of heat to distribute 

 to objects around it than other substances at the same tem- 

 perature, because it absorbs more heat than the other 

 substances do, while gaining the same number of degrees. 

 Water is not so good a conductor of heat as metals, rocks, 

 or other solids, and for this reason does not distribute its 

 heat so rapidly to the surrounding air. As it is commonly 

 expressed, " water keeps warm longer." 



These facts have a very important bearing on the sub- 

 ject of the climate of islands and of land near a large lake 

 or an ocean. 



A great lake or an ocean, having been slowly heated 

 through the summer to a temperature of 75 F. or 24 C., 

 has a great quantity of heat to transfer and will do it slowly. 

 The land loses heat rapidly after sunset, but near a lake or 

 ocean the air receives heat from the water during the night 



