Mance: Quarry Industry of Southern Indiana 165 



the fibres which swell the hides. The length of time that the 

 hides undergo this liming process determines the pliability of the 

 leather formed. The addition of sodium sulphite to the lime 

 gives a paste that will remove the hair in a few hours if spread 

 on the hair side and roiled in. 



I have attempted to outline here only a few of the more 

 important chemical uses of iime. A discussion of these industries 

 can be found in any of the later textbooks on industrial chemistry. 



It will be seen from the lists given at the beginning of this 

 section that high calcium limes are far more important and have 

 a much more extensive use in the manufacturing industries of 

 I the country than the magnesium limes or those burned from 

 dolomite. 



The demand for these manufactured products is sure to in- 

 I crease very rapidly in this country during the next few years 

 and the demand for lime wUl increase accordingly. The price 

 of high-grade, high-calcium limes is sure to increase with the 

 increased demand for them in the new manufacturing projects 

 that are sure to spring up in the next decade. 



The vast diversity of the uses of lime is sure to keep the 

 I demand constant even if the different industries make vary- 

 'l ing demands for it. The ability of lime to correct soil acidity has 

 j been thoroly treated in that part of this paper treating of the use 

 of lime and limestones on acid soils. 



The Hydration of Lime. When a magnesium lime is 

 packed for shipment its slow-slaking properties and the small 

 amount of heat given off in slaking make it possible to keep it a 

 I long time and to ship it in paper sacks without fear of their de- 

 struction or danger to property near it. This is not true of the 

 hot, high-calcium limes. Their great affinity for water has 

 always made them dangerous to property and has caused them 

 to spoil in storage or transit. In most industries the hydrate 

 fj of lime is as useful as the pure quicklime and much easier to 

 j| handle, being also less liable to spoil. This demand for a compound 

 j easily handled and shipped led to the placing of lime hydrate on 

 I the market. In any process by which quicklime and water are 

 (I brought together, the same chemical reaction results, namely: 



jl CaO + H2O = Ca(0H)2 



When the oxide leaves the kiln it is in lumps about one-fourth 

 iarger than the lumps of limestone from which it was burned. 

 These lumps on slaking fall into a fine white powder known as the 



