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Indiana University Studies 



hydrate of lime. The reaction is accompanied by the genera- 

 tion of an amount of heat that under some conditions is sufficient to 

 cause combustion. When this reaction has been completed 

 and the resulting lime hydrate has cooled and dried, it can be 

 stored or shipped without any danger to property or to itself. 

 The lime hydrate contains about 25 per cent of water and has a 

 specific gravity of about 2.08 while limestone is about 2.8. The 

 specific gravity of pure lime oxide may be as high as 3.1. 



The burning of the lime has much to do with the rapidity 

 with which it slakes. Lime burned at temperatures under 

 1,000 degrees Centigrade will slake quickly, while limes burned 

 at higher temperatures may take hours to slake thoroly. When 

 a hot lime and water are mixed, temperatures as high as 310 

 degrees Fahrenhe't may be reached; this temperature is often 

 sufficient to cause combustion. 



To slake the lime properly the water must be added slowly. 

 About one-third of the amount of water necessary to slake the 

 lime should be added first, and after the heat is generated the 

 rest of the water may be added. If the lime is mixed with a 

 large amount of cold water the product will be very granular. 

 The weight of high calcium limes is increased about one-third 

 in slaking. One bushel of good lime will when slaked make 

 about 23/2 bushels of slaked lime with a weight about one-half as 

 great per bushel. 



The old method of lime hydration practiced by masons 

 and plasterers consisted in pouring the necessary amount of 

 water over the lime in a water-tight box lined with san l and 

 lime paste. The lime was spread over the bottom of the box 

 in a layer about 8 inches thick and enough water added to make 

 a thick paste. A layer of sand was then spread over the lime to 

 keep in the heat. This method when properly carried out by 

 an experienced man gives a good product, but careless work 

 usually injuries the lime and makes it inferior as a building ma- 

 terial. The new method of lime hydration at hydrating plants 

 and the marketing of the product already slaked do away with 

 the danger of careless slaking; and the resulting product gives 

 much better satisfaction as a building material. 



Many processes are now in use for slaking lime. Several 

 of them are operated under patents and the product sold under 

 various names, such as lime hydrate, limoid, cream of lime, etc. 

 The process consists essentially of the following operations: 

 first, crushing the lime lumps with some type of crusher to give 



