240 ANALYSES OF SOILS. 



in it. It is quite refractory in the fire, and fuses only after urging the heat of the furnace. 

 Its fineness fits it for looking-glass frames, forming a base on which to gild ; besides which, 

 it will undou'otedly answer for all the ordinary purposes of potter's clay. It is now used 

 only for brick, the color of which is a pale yellow brown. It is composed of the following 

 elements : 



Water of absorption ^. 2'284 



Water and organic matter 4 -240 



Silex 60-160 



Peroxide of iron and alumina 7*790 



Carbonate of lime 0*940 



Carbonate of magnesia 0-600 



Carbonate ot potash O-llO 



Phosphate of lime amount undetermined. 



Chlorine trace. 



Sulphate of hme none. 



~ ■ 76-124 



The specific gravity of the Adirondack clay is 2' 1034, which may be taken as a standard 

 for stiff clays that are destitute of organic matter. 



Had this clay been derived from an ordinary coarse granite, one whose felspar and mica 

 contain potash, it would probably have formed the porcelain clay. Lime is a more stable 

 element, less soluble than potash, and hence it has been retained, and remains in combi- 

 nation with tlie silex, or perhajjs with carbonic acid. It does not effervesce with acids. 

 The existence of this clay in the midst of tliis highland district offers encouragement to 

 look for deposits of the same material in all of our other primary or mountainous districts. 



The Southern Highland district, in consequence of its insulated position and its limited 

 extent, furnishes but imperfect examples of a primary or granitic soil. On the eastern 

 side of the Hudson river, near Peekskill, gneiss and granite prevail. In consequence, 

 however, of the proximity of the slates and limestones of the Taconic systeiri, the great 

 mass of soils seem to belong rather to the latter than the former rocks : they possess at 

 least a mixed character. We find limited areas where the primary rocks have been de- 

 composed, and in which particles of mica and felspar abound ; but we have not submitted 

 the soils occupying such limited areas to analysis. 



The following result of a chemical examination of the soil of Peekskill, resting oji 

 granite, must sufRce for this part of the Highland district : 



Water of absorption 2-79 



Organic matter 7-65 



Silex 75-83 



Peroxide of iron and alumina 12-00 



Carbonate of lime 1-15 



Magnesia 0-68 



100-lQ 



