I^IME AND CEMENT INDUSTRIES 659 



not turn into lime. Aluminous limestone clears with difficulty 

 when dissolved, and hence is not liked by bleachers and paper 

 manufacturers. 



As the consumers require a pure white lime, the stone must 

 contain practically no manganese or iron. These impurities are 

 thought by some to also injure the stability of the lime chlorid, 

 but this point is not definitely proved. The presence of mag- 

 nesia is also undesirable, as the greater deliquescence of the mag- 

 nesium chlorid renders the lime chlorid less stable. The presence 

 of organic or bituminous substances in the limestone is entirely 

 harmless, as they do little more than impart a dark color to the 

 stone and pass off in burning. ■"■ 



Fat limes which slake quickly and fall easily to a fine, 

 light powder absorb chlorin much more quickly than lean limes, 

 which on slaking give a sandy powder. In addition, chlorid of 

 lime made from fat limes keeps much better than that made from 

 lean limes.^ 



Carbon dioxid 



A considerable amount of nearly pure dolomite has from time 

 to time been shipped from the quarries at Pleasantville, West- 

 chester CO., for the manufacture of carbon dioxid. The stone 

 was ground at the mines almost to the fineness of granulated 

 sugar. From the grinder it passes into hoppers, whence it is 

 fed automatically through tubes into barrels for shipment. The 

 Quaternary marls near Caledonia have found favor for the same 

 purpose, being utilized in Buffalo. 



Soda manufacture 



In soda-making by the Le Blanc process limestone is used to 

 transform the sulfate of soda into caustic soda, the reaction being 

 thus. 



2NaCl 4- H3SO4 = :^a2S04 + 2HC1 ; NagSO^ -{-2C = ^a^ 

 S -f 2CO3; NagS-hCaCOg^NaaCOg + CaS. 



1 Wagner. Chemische technisehe untersuchung's methoden. 1893. p. 430. 



2 Wright. C. R. A., Chem news. 16: 12G. 



