DOMAIN V. CALCAREOUS, 



mere sub-species, or varieties of limestone. 

 Strict chemical analysis may probably dis- 

 cover a different proportion of ingredients, 

 as, for examples, more water of crystallisa- 

 tion in marble, and more or less silex or 

 argil ; and there is at any rate a difference 

 in the mode of combination. But the chief 

 use of any system being to assist the me- 

 mory, even the strict precision of terms 

 becomes mere pedantry, if it be not sub- 

 servient to this main object. Too large 

 masses of colour, or too small, will render 

 the picture equally inelegant and obscure. 



