30 
[Assembly 
Carbonic acid, 40.95 
Lime, 29.00 
Magnesia, 17.30 
Silica and alumina, 11.00 
Oxide of iron, 1 . 10 
Moisture and loss, 0.65 
100.00 
If this composition is constant, it is not difficult to account for the 
occurrence of sulphate of magnesia or Epsom salt, which is so often 
found in efflorescences on this rock. It contains a sufficient amount of 
sulphuret of iron to furnish the acid for this decomposition.* 
45. An important locality of water limestone occurs about a mile and 
a half west of Manlius in Onondaga county. The overlying rock is a 
blue limestone, similar to that found at Chittenango. Some of the 
strata of water limestone are clouded or striped, while others are of a 
uniform gray or drab colour. Through the upper layers there passes a 
thin seam of white calcareous spar, in which are to be found small crys- 
tals of fluor, of a dark purple colour. 
The cement manufactured at this quarry is used in the construction 
of the aqueduct at Syracuse, and in that of several of the locks on the 
enlarged canal. 
* Since the above was written, I have analyzed a specimen from the bed of the river at Ro- 
chester, Monroe county; called " calcifero us slate" by Prof. Eaton, and "calcareous shale" 
by Mr. Hall. It is greyish blue, granular, a little crystalline, and emits a strong bituminous 
odour when struck or subjected to heat. Its composition is as follows : 
Carbonic acid, 35.00 
Lime, 25.20 
Magnesia, 14.50 
Silica, with a little alumina, 24.00 
Oxide of iron, A . . ; 1 .00 
Bituminous matter, • . . . 0 . 30 
100.00 
I have also analyzed a specimen of the tufa or petrified wood found at the base of the hill of 
calciferous slate at Chittenango, for the purpose of ascertaining whether magnesia was one ©f 
Its constituents. The following is its composition. 
Carbonic acid, '.v 42.05 
Lime, 53.95 
Silica, alumina, and vegetable matter, 2.10 
Oxide of iron, 0.80 
Moisture and loss, 1.10 
100.00 
It does not contain even a traee of magnesia. 
