844 
[Assembly 
We find a continuation of the rocks just mentioned j on Mr. Shum- 
way's farm in Sweden, two miles south of the canal. At this locality 
the rock is of a light gray colour, fine grained and compact. The more 
siliceous portions would doubtless make good hydraulic cement, at least 
equal to that brought from more distant localities. 
Some of the strata at the limestone quarries in Mendon would make 
hydraulic cement, but the character of the different strata is so variable 
that its quality could not be relied on unless constantly exammed as it 
is used. The same rock is found in Wheatland, in the vicinity of Al- 
len's creek, but at this place it does not make hydraulic cement. 
The rock used in this county for cement, is usually blue or greenish 
blue when first exposed to the atmosphere, but becomes rusty gray and 
partially decomposed by atmospheric agents. In the locality last men- 
tioned, the original colour of the stone is gray, or of the colour of pipe 
clay. 
Hydraulic cement can be obtained within five miles of the canal 
throughout the whole extent of the fourth district. The same rocks 
which furnish the article at Onondaga, continue to the Niagara river, 
and a few experiments will prove that fifty or one hundred localities 
can be found to afford good cement. 
Fire Stone. 
A stratum of light gray siliceous limestone, of a porous texture, ex- 
tends through the towns of Ogden and Sweden. This stone resists the 
action of ordinary fires for' many years with little apparent loss or 
change. Its character depends on the presence of siliceous and magne- 
sian earths, and the porous structure of the stone, which prevents it 
from cracking when heated. The stone can be obtained of any desira- 
ble dimensions at the quarry of the Messrs. Fenton, two miles south of 
Brockport. It is much used in this neighborhood for the backs and 
jambs of fire places, and also for door and window caps and sills. At 
the place where the stone is quarried the stratum is not seen in place, 
but masses of the broken outcropping edge are used. 
Some of the strata of the gypseous rocks are sufficiently siliceous to 
be a good fire stone, and have been used for hearths of iron furnaces. 
Some of the more siliceous strata of sandstone furnish a good fire 
stone, where great heat is not required. 
