1) The temperature scale where 32 degrees is the freezing point of water and 212 degrees at 760mm Hg (sea level) is the boiling point of water. To convert from Fahrenheit to centigrade, subtract 32 and then divide by 1.8 ((F-32)/1.8). To convert from centigrade into Fahrenheit, multiply the centigrade temperature by 1.8 then add 32 to the product (C*1.8+32=F). This scale is named for G. D. Fahrenheit (1686-1736), the German physicist, who invented it and was the individual who introduced the use of mercury (Hg) instead of alcohol in thermometers. Because of the health dangers related with mercury, the use of mercury in thermometers is losing favor and once again alcohol thermometers are becoming more popular.