356 



COMPOSITION OF SHALES, 



the decomposed mica slates have been aheady thus employed. Dr. Jackson, in his New- 

 Hampshire Report, gives the aiialysis of one which experience has proved valuable in this 

 way by mixing its debris in a compost of peat, lime, etc. 



ANALYSIS BY DR. JACKSON. 



Water 3-6 



Vegetable matter 1-8 



Silica 79-2 



Peroxide of iron and alumina 5-6 



Potash 2-2 



Soda 2-5 



Lime : 3-2 



Magnesia 1 '2 



99-3 



The composition of this primary slate may be compared with the laconic slates. We do 

 not, however, mean to convey the impression that slates and shales are definite chemical 

 compounds ; and yet there is little doubt but that analysis gives their general constitution, 

 and that they will not be found to vary excessively from the composition which we have 

 found (hem to possess. 



COMPOSITION OF THE SLATE.S AND SHALES OF NEW-YORK AND OTHER PLACES. 



Hoosic roofinp; slate 



Slate from Salem 



Waterville, Me 



Fairhaven 



Welch roolin2; slate 



Shale from CortlandviUe 



Cauda galli grit 



Marcellus slate 



Red slate or shale of the salt group. 

 Green shale of the salt group 



3-32 

 1-52 



I 



* Lose may be set down as potash and ibe pbosphaien probably- 



Clays of new-york. 



Clays are highly important materials in the constitution of soils. They are also im- 

 portant fertilizers, especially when they contain lime, magnesia and potash ; but they are 

 more valuable in pottery and brick making. Some kinds of clay, as is well known, enter 

 into the composition of the finest works of art — the porcelain ware. The expense of 

 moving clay may be considered as the great l)ar to its use as a fertilizer, and yet its effects 

 are most decided upon all lands which are denominated light. 



The Albany or Tertiary clay extends through the vallies of the Champlain and the 



