CHEMICAL CHANGES DURING DECOMPOSITION. 



513 



Supposing the amount of silica remains constant in a limestone, the 

 original composition and the losses are as follows : 



Table VII. — Analyses of fresh and altered limestone. 



While in the foregoing tables, with the exception of one rock spoken 

 of as disintegrated, the altered forms of the rocks are classed as decom- 

 posed, it must be understood that these terms are relative. In the so-called 

 mon xlvii — 04 33 



