64 [Assembly 
Insoluble matters, (silica and alumina,) 12.25 
Bituminous matter, 0.25 
Carbonate of lime, 51.00 
Carbonate of magnesia, 36.50 
It is therefore similar in its composition to the water limestones found 
in other parts of the State.* 
There is a sulphur spring of some character four miles from Buffalo, 
and a spring on Grand Island is interesting in consequence of its con- 
taining free sulphuric acid although in a very dilute State. Petroleum 
is also found floating on the surface of many springs, but it is by no 
means abundant. 
It remains only for me to notice under this county those septaria or 
rolled masses of impure limestone to which I have previously referred. 
These as they are found here are entirely similar to those which occur 
in Chautauque county. They commonly exhibit on the outside, sutures 
which pass in various directions, and are generally composed of mine- 
rals different from those in other parts of the mass. They are either 
folia or blades of sulphate of barytes, or crystals of calcareous spar or 
brown spar, with occasionally some anhydrite. f 
ESSEX COUNTY. 
Unlike the preceding, this county possesses immense mineral re- 
sources. Enough is already known to warrant this assertion, but many 
years must elapse before a correct estimate can be formed in regard to 
their real extent and value. To say that there are here numerous beds 
of magnetic iron ore, would scarcely convey a true idea of the enor- 
mous deposits of that mineral which are found in various parts of the 
county. Some notices of these have already been published in the re- 
ports of Dr. Emmons and Mr. Hall. The ore is every where of suffi- 
cient purity for the manufacturer, and if only a small proportion of it 
* Another specimen of water limestone from Williamsville in this county, contains 
Silica and alumina, 18.45 
Bituminous matter, 1.30 
Carbonate of lime, 46.25 
Carbonate of magnesia, 34.00 
t The occurrence of this mineral in the septaria is given on the authority of Mr. 
Vanuxem. New- York Geological Reports 1837, p. 191. 
