Mance: Quarry Industry of Southern Indiana 195 



Lime, or more properly calcium, is obtained from limes or finely 

 ground limestone. The lime has been used much longer than the 

 limestone, but has always giA'en more or less trouble on account 

 of the fact that it changes in volume as it takes up carbon dioxide 

 from the air. This makes it difficult to mix the constituents of 

 the glass in the correct proportions. The fact that the only form 

 in which the limestone can be used is as a finely ground powder 

 makes this a very good way for the plants turning out grotind 

 limestone for fertilizing purposes to dispose of their product 

 during the dtill season. The one plant already turning out 

 ground limestone in the ciuarry district disposes of a large amoimt 

 of its surplus product in this way. 



The ground hmestone can be used at the same mesh for glass 

 manufacture as for fertilizer, thus doing away with the necessity 

 of installing extra screens. The manufacture of glass in this 

 country has increased notably in the last year or so and is sure to 

 grow into a large industry in the next few years. 



The chemical composition of the limestones of the Southern 

 Indiana quarry cUstrict makes them very well adapted to the 

 manufactiUT of glass since they are very high in calcium car- 

 bonate and contain only traces of iron and aluminum. The 

 demand for the ground limestone of this district is sure to grow 

 when it becomes generally known that the chemical composition 

 of the stone is so well adapted to this industry. 



The final reactions in the manufacture of lime glass are as 

 follows : 



Xa.COs + CaCOs ^ 2SiOo = XaoCa (SiOsJo + 200. 

 Or. Xa^SiOs CaCOs + SiO^ = Xa.:Ca (SiOsio + CO-2 



Data on the amount of stone used for the purpose of glass 

 manufacture in this country are not at present available, since 

 the U. S. government in its reports on the amount of stone used 

 puts the stone used in glass factories, paper mills, carbonic acid 

 plants, and for fertilizing purposes in one group, for the reason 

 that it is as yet impossible to secure separate data on each of 

 these. 



Limestone in the LeBlanc Process of Soda Manu- 

 facture, As the result of chemical experiments encouraged by 

 the olfer of a large prize by the French Academy of Science in 

 1775. Nicholas LeBlanc patented the process of soda manu- 

 facture which remains in use to the present time. The only 

 process at present that offers competition to it is the Solvay 



