32 
[Assembly 
Gypsum, when pure, has a snow white colour, but it is often tinged 
with red, yellow, blue and grey, in consequence of the admixture of 
foreign substances. When crystallized, it is foliated, but it also occurs 
granular and compact. The foliated varieties are called selenite^ while 
the compact ones are often known by the name of alabaster. It is dis- 
tinguished from carbonate of lime by its being less hard, as it may be 
scratched by the finger nail; acids, when applied to the carbonate of 
lime, cause an effervescence, owing to the escape of carbonic acid, — but 
no such effect is produced by a similar application to the sulphate of 
lime. 
The variety of sulphate of lime which is most abundant, is composed 
of sulphuric acid and lime, with about twenty per cent of water. When- 
ever it is used for architectural purposes, this water is driven off by the 
application of heat, the operation being commonly known by the name 
of bmling. The calcined or boiled plaster, when made into a paste with 
water, speedily hardens, and it is employed in this way for walls, for 
stucco, for taking casts of statues, in stereotyping, &c. Gypsum is 
moreover largely used in agriculture, and it is considered an invaluable 
fertilizer. 
Of this useful mineral we have numerous and very important locali- 
ties. They are, however, almost exclusively confined to the district 
bordering on the Erie canal. I am aware that it occurs in the counties 
of Columbia, Albany and Schoharie, but however interesting the speci- 
mens here procured may be for the cabinet of the mineralogist, the quan- 
tity is nowhere sufficient to answer any other purpose. 
50. The west end of the town of Starke, in Herkimer county, is the 
most eastern point at which gypsum has been found in any great quan- 
tity. According to Mr* Vanuxem, it occurs in a white sandstone, the 
grey band of Mr. Eaton, and he represents it as being white and equal 
to the Nova Scotia both before and after calcination. From twenty to 
thirty tons had been obtained by Mr. Grill, the proprietor, during the 
summer of 1837. 
51. In Oneida county, gypsum is found in beds of vast extent. It is 
sometimes pure, being foliated and transparent; but the largest propor- 
tion is dark coloured, and is mixed with carbonate of lime, constituting 
what is usually called plaster stone. This last is used for agricultural 
purposes, and when deprived of its water by calcination, as a cement. 
