How Chalk is Made 



a small manufactory for producing or " secreting " 

 carbonate - of - lime. The materials are obtained 

 by the snail through its food. The deposits of 

 it made as the snail's nature, certainly not the 

 snail's reason dictates, grow into a sheltering 

 framework for its protection. 



In a Dictionary we may find the strict meaning 

 of this word " secrete." It is given as "to 

 hide ; to conceal ; to deposit in some secret or 

 private place ; to separate from the blood in 

 animals, or from the sap in vegetables, and 

 elaborate into a new product." 



One cannot deny that the word, though used 

 for all such " elaborations," is more appropriate 

 in the case of a man's hidden and private frame- 

 work of bones, than in a snail's or jelly-creature's 

 outside shell. 



That which the garden-snail so deftly does, 

 is done also by countless billions of minute 

 jelly -specks in the ocean; though with the 

 latter the mechanism is far simpler, because 

 the animal belongs to a far lower and more 

 primitive type. 



Still, simple though the apparatus may be, the 

 tiniest of these jelly-specks has power to separate 

 lime from ocean-waters, to unite it with carbonic 

 acid in its own frame, to form carbonate-of-lime 



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