28 
[Assembly 
By calcination, therefore, this limestone is reduced to a state ap- 
proaching that of a double silicate and aluminate of lime and magnesia, 
and the theory of the hardening of this cement is sufficiently in accord- 
ance with the views above suggested. The cement, moreover, forms a 
jelly with muriatic acid, which still further proves that its chemical na- 
ture has been changed during the calcination. 
38. An important practical inference from these experiments and ob- 
servations is, that the more completely the carbonic acid is driven off 
from the limestone by calcination, without causing its fusion, the more 
energetic will be the resulting product. It is probable that a long con- 
tinued, rather than a very high, heat, will best effect this object. 
39. It remains to be mentioned, that the limestone which over lies 
this cement has a blue colour, a structure somewhat granular, contains 
organic remains, and occasionally nodules of calcareous spar and sulphu- 
ret of zinc, with alternating layers or masses of hornstone. On ana- 
lyzing a fragment of this rock, I found it to consist of carbonate of 
lime, with a minute portion of oxide of iron and bituminous matter, 
and with about eight per cent of argil, or silica and alumina. It does 
not contain even a trace of magnesia, although so closely associated 
with the magnesian stratum above described. 
40. Water limestones occur in Albany county, in the Helderberg;* 
in Montgomery county, about ten miles northwest of Schenectady; also 
in Herkimer county, some of which Mr. Vanuxem thinks would afford 
cements equal to any elsewhere made in the extensive range to the west; 
while, according to the same geologist, they are found in immense series 
in Oneida county .f 
41. The hydraulic limestone of Madison county has long been in high 
repute. One of the most important localities, and I believe one of the 
first, if not the very first, discovered in the State, is situated about a 
mile and a half southwest of the village of Chittenango. It has usu- 
ally a drab colour, sometimes striped with reddish bands, a conchoidal 
fracture, an earthy texture, and is covered by layers of the calciferous 
slate of Eaton. The process of burning and grinding is similar to that 
heretofore described. When this cement is used in the construction of 
works, it is mixed with from two to three parts of sand. 
* I have not yet had an opportunity of analyzing a specimen from this locality. According 
to an analysis of Prof. Eaton, which, however, he did not deem very accurate, it contains 25 
per cent carbonic acid, 26 lime, 28 sihca, 18 alumine and magnesia, 1 iron, and 2 water.— 
Transactions of the Albany Institute, vol, 1, a^p, p. 53. 
t Mr. VanuxeJn's Report for 1838. 
