CHAPTER IX 



LIME 



TO make mortar with which masonry is held in 

 place it is customary to use lime. In a sort of 

 trough lined with sand are placed lumps of stone 

 having a calcined appearance, and on these stones 

 water is poured. In a few moments the pile becomes 

 heated to high temperature, cracks and splits and 

 finally crumbles into dust, at the same time absorb- 

 ing the water, which disappears little by little as it 

 is taken up by the solid matter or vaporized by the 

 heat. More water is added to reduce it all to paste, 

 which is finally mixed with sand. The product of 

 the mixture is mortar. Such is the process often 

 witnessed by Emile and Jules, who are always sur- 

 prised, that stone, by having water poured on to it, 

 should become hot and turn the water into jets of 

 steam. "Lime," Uncle Paul explained to them, "is 

 obtained from a widely diffused stone called lime- 

 stone or, in more learned language, carbonate of 

 lime. The process is of the simplest sort. It con- 

 sists of heating the stone in kilns built in the open 

 air in the vicinity of both limestone and fuel, so as to 

 avoid the expense of transportation in the manufac- 

 ture of a product that it is desirable to furnish at a 

 low price. 



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