4d 
FLORIDA GEOLOGICAL SURVEY. 
LIME AND CEMENT. 
Lime. 
Lime or “quick lime” is chemically an oxide of calcium 
or calcium and magnesium. It is formed ordinarily by 
burning limestone, although shells and other calcium car¬ 
bonates may be used for the same purpose. Limestone 
when burned gives up carbon dioxide. The residue after 
burning forming a lime, consists of a calcium oxide, when 
a pure calcium carbonate limestone is used; or of calcium 
and magnesium oxide when a dolomitic limestone is used. 
The reaction in the case of a pure limestone is as follows: 
Ca(CO) 3 when heated breaks up into CaO+(Co) 2 . In 
the case of dolomitic limestone a magnesium oxide as well 
as calcium oxide is formed. 
The character of the lime varies according to the 
amount of magnesium present in the limestone from 
which it is made. Peppel* offers the following classifi¬ 
cation of the ordinary or “white limes”, including in that 
term limes containing not more than 5 per cent of sandy 
and clayey impurities:— 
(1) High-calcium, or “hot” or “quick” limes. Made from lime¬ 
stones containing not less than 85 per cent, of carbonate of 
calcium. 
(2) Magnesium limes. Made from limestone containing be¬ 
tween sixty-five and eighty-five per cent, carbonate of calcium and 
between ten and thirty per cent, of carbonate of magnesium. 
(3) Dolomitic, or “cool”, or “slow” limes. Made from lime¬ 
stones containing more than thirty per cent, of carbonate of mag¬ 
nesium. 
These limes differ slightly among themselves. The high 
calcium or “hot” or “quick” limes set more quickly, while 
the magnesium and dolomitic limes set more slowly. Limes 
thus serve different purposes, the high calcium limes 
being used when a quick-setting lime is desired, while 
* Bulletin No. 4, 4th Series, Ohio Geol. Survey, p. 254, 1906. 
