ARITHMETIC 



301 



The monetary units of leading foreign nations and their 

 equivalents in United States money are as follows. These 

 rates are proclaimed each year by the Secretary of the 

 Treasury. 



HEAT 

 SPECIFIC HEATS OF METALS 



The specific heat of a substance is the number of heat 

 units required to raise a unit mass of the substance one 

 degree in temperature. The specific heat of water is very 

 nearly constant for all temperatures, but that at its tempera- 

 ture of maximum density (4 C. or 39.1 F.) is considered 

 unity. The specific heats of most substances increase with 

 increasing temperatures. 



HEAT UNITS 



One British thermal unit (B. T. U.) is the quantity of heat 

 required to raise the temperature of 1 Ib. of pure water 1 F. 

 at or near its maximum density, 39.1 F. 



One calorie is the quantity of heat required to raise the 

 temperature of 1 Kg. of water 1 C. at or near 4 C. 



