Mance: Quarry Industry of Southern Indiana 



151 



this district would be classed as a high calcium lime. In other 

 words, it would be composed of almost pure calcium oxide. 



In the TT>s/ VirginiaGeological Survey, Vol. iii, p. 324, Professor 

 Grimsley describes lime oxide as follows: 



Lime oxide when pure is a white solid, ^^ithout crystal form, infusible 

 and non-volatile at temperature below 3,000 degrees Centigrade. The 

 commercial oxide is more or less tinged with color due to impirrities present . 



The metalKc lime [calcium] free from oxygen may be made by electrolysis 

 of fused lime chloride, or more readily by heating seven parts of the iodide 

 of Hme with one part of sodium in a crucible. The metal is yellow in color, 

 soft, with a specific gra^dty of 1.578. It is said to be both malleable and 

 ductile and does not tarnish in diy air. If heated in a current of air or 

 oxj'gen the metal burns into lime oxide with a very brilliant light. 



Lime oxide in a very pure form may be obtained by heating the nitrate 

 of lime Ca(X03)2. 



AYhite lime slakes readily and rapidly with the evolution of 

 much heat and becomes a perfectly white paste. Any impurities 

 present tend to retard this chemical action. The presence of 

 magnesium makes the process much slower, and less heat is 

 evolved. Limes containing less than 10 per cent of ^IgO show 

 no effect, but as soon as the amount goes above this figure the 

 slowing up of the reaction is noticeable. 



The presence of aluminum and silicon oxides in a limestone 

 tends to color the lime produced a gray color, but when present in 

 small quantities they only make the action of the lime less vigor- 

 ous; that is, these impurities do not ordinarily exert any chemical 

 influence or in any way change its physical properties. They 

 have a diluent action the same as sand when mixed with lime 

 to produce mortar. If this alumina or silica be present in finel\^ 

 divided particles it will be susceptible to chemical combination 

 with the lime if the temperature employed in burning the lime be 

 high enough. As these constituents increase the limestone is 

 called argillaceous or arenaceous and from this it grades into 

 shales or sandstones according to whether the diluent is clay or 

 sand. The presence of these impurities in a small proportion 

 produces on higher heating a hydraulic lime; that is, it gives a 

 hme that possesses the property of setting under water. When 

 the quantity of clayey impurity in a limestone reaches 6 per cent 

 it begins to produce hj'draulicity, but below this percentage its 

 only noticeable effect is a retardation of slaking. In fact, many 

 limestones containing between 6 and 12 per cent of clayey im- 

 purities make good cool, slow-slaking limes, but the risk of over- 



