346 
SOURCES OF THE PHOSPHATES. 
The specimen of taconic slates belonging to New-York, not proving so rich in phosphates 
as that from Maine, I made an examination of another specimen, which was softer, as No. 
3 had proved more siliceous than was anticipated. Hence I selected a soft variety, which 
occurs in a compact slate at Salem, and which is extensively used for the foundation of 
buildings. As my object principally was to ascertain the constancy of the phosphates in 
these slates, I proceeded no farther than was necessary to test, in a satisfactory manner, 
this question. A solution, therefore, of 100 grains was made, after thorough boiling in 
chlorohydric acid; the solution was freed from silica, and the alumina, iron, etc. with the 
phosphates precipitated. The last precipitate was again dissolved, and exactly neutralized 
by caustic ammonia ; when acetate of potash threw down, in a short time, a large quantity 
of the phosphates. From this examination, it appears that the phosphates are commonly 
present in these slates, and greater in amount in the softer than in the harder and more 
siliceous ones. 
It will be observed that the roofing slate of Hoosic contains quite a large percentage of 
potash. This potash may be in a larger quantity in the fucoidal slate, than in those which 
are destitute of the marine productions. 
From the foregoing observations, we are furnished with a clue to the source of the im¬ 
portant elements, potash, and the phosphate of alumina, iron and lime, which are so 
frequently contained in the soils of the Eastern or Taconic district. 
We may now proceed to state the results which we have obtained by a special examina¬ 
tion of the softer shales and slates situated geologically above the Tully limestone. I 
selected, for this examination, a specimen of slate from a quarry south of Cortlandville. 
It was greenish, and contained the fossils which characterize the Ithaca group, or the lower 
part of the Chemung group. 
ANALYSIS. 
Water_____-_ 3'03 
Silicates_83'50 
Peroxide of iron and alumina_ 12'56 
Carbonate of lime_ 0'61 
Magnesia___ O'30 
100*00 
Phosphates appreciable in 100 grs. Potash was not obtained. The presence of 
phosphates was clear and distinct. 
From this examination, we find an explanation of the fact why indian corn is a better 
crop upon those lands situated above the Onondaga-salt group, than it is below or imme¬ 
diately upon this series, inasmuch as it has been shown that the Onondaga-salt group is 
comparatively destitute of the phosphates. 
Where fossil remains are abundant, we may always expect to find phosphates. In the 
above analysis, we selected a piece which was destitute of organic bodies ; and it seems 
