1846.] Agricultural Geology of Onondaga County. 165 



The composition of the hopper-form masses is as follows: 



Almnina and protoxide of iron, - 13.36 

 Sulphate of lime, - - 1.00 



Magnesia, - - - - 2.17 



99.71 



The red marl and the green marly rock just described, when 

 submitted to the action of cold water, furnish directly a quan 

 tity of soluble matter: thus 100 grains yield in 6 oz. rain water: 



Those rocks after they have undergone decomposition, furnish 

 a still larger amount of saline matter, but it is composed in every 

 instance of the same elements, among which the sulphates and 

 chlorides are the most abundant, as shown by the following 

 analysis: 



Debris of the Shale. 

 WTiole amount of soluble matter, - - - 6.53 

 Vegetable matter, - - - - - 1.03 



Saline, --_-___ 5.50 



The latter consists of chlorides of sodium and calcium, sul- 

 phates of lime and magnesia, together with a small percentage of 

 alumina and silex. 



It can hardly be expected, however, that rocks will be com- 

 posed of the same elements, but all the specimens which were 

 examined fiu"nished soluble matter in pure rain water without 



