SOURCES OK THE PHOSPHATES. 345 



X. SOURCES OF THE PHOSPHATES WHICH ARE FOUND IN THE CORN AND 



GRAZING SOILS OF NEW- YORK. 



It has been supposed that the phosphates were derived from the comminuted primary 

 rocks contained in soils. Professor Fownes, author of a well known prize essay, has given, 

 in an appendix to Ins work, several analyses which he had made for the purpose of settling 

 the point whether the phosphates were contained in the ordinary granites. His results 

 confirmed his suspicions, namely, that the phosphates were generally appreciable in the 

 granites, when a thousand grains were operated upon. In the New-England soils, the 

 disintegrated gneiss, mica slate, and granite which composes in the main those soils, con- 

 tain the phosphates of the alkalies and alkaline earths. In two of the districts which we 

 have closely examined, the phosphates are quite abundantly locked up in the rocks, and 

 may be obtained when the analysis is conducted with ordinary care. Suspecting that the 

 taconic slates might contain these important elements, several analyses were undertaken for 

 the purpose of ascertaining the truth of my conjectures. It was not, however, the principal 

 object to test the question merely for the local fact, but for the purpose of ascertaining a 

 more general result, one which should have an important bearing upon a widely extended 

 formation. I therefore selected a specimen of the taconic slate from Waterville, Maine, 

 and several from Washington county, New-York. Prof. Jackson, in his survey of Maine, 

 had found phosphates of magnesia in those soils ; and as the slates of Waterville are 

 identical with the New- York slates which belong to the same system, it appeared highly 

 probable that this formation would be found to contain the phosphates which had been 

 detected so frequently in the soils which rest upon those slates. I give the following- 

 results, as the analyses show other elements of importance besides the phosphates. No. 1 

 is the Hoosic roofing slate, which contains the beautiful fucoid that I have already referred 

 to. when treating of the Taconic system ; No. 2 is the Waterville slate, Me.; and No. 3 

 is the crystallized taconic slate, near and just west of the village of Salem, Washington 

 county. 



ANALYSIS. 



No. 1. No. 2. No. 3. 



Water 3-79 3-42 2-62 



Silica 70-55 71 -62 84-65 



Alumina and peroxide of iron 20-35 23-25 11-53 



Carbonate of lime 0-99 0-10 0-60 



Potash 3-52 1-52 0-00 



Carbonate of magnesia 0-40 0-05 0-60 



Soluble silica trace. trace. trace. 



Phosphates trace. 0-90 trace. 



The potash obtained was merely^ a trace ; and the phosphates did not appear, until the 

 solution had been standing twenty-four hours in No. 3. 

 [Agricultural Report.] 44 



