t 104 ] 



Mode of analyzing and testing Gypsum ; extractedfrom 

 Professor Cooper'' s account of his experiments on suU 

 phat of lime* Cooper's Emporium, New Series, vol. 

 I, page 325. 



I procured 150 grains of gypsum from 100 of pure 

 limestone, when the gypsum after being carefully wash- 

 ed in a moderate proportion of water, was dried for an 

 hour on the top of a ten plate stove, on which I could 

 just bear my hand. But when I calcined it for an hour 

 in a full red heat, I procured from 100 grains of car- 

 bonat of lime, but 130 grains of gypsum. 



I took a well characterized piece of compact gypsum 

 from a ton that lay for sale in the street here ; and re- 

 ducing it to fnie powder, I calcined it in a crucible 

 in difull red heat for an hour. 1 drove off 2\~ parts : 

 this occurred to me three times. 



I took from a lump of the sane gypsum (Nova Sco- 

 tia, imported to Baltimore, and thence sent to Carlisle) 

 some of the semi-transparent chrystals of a vein that 

 ran through the lump. Exposed to heat in the same 

 manner, the result was the same. 



Hence I conclude ; that 100 parts of pure carbonat 

 of lime, will yield 130 parts of anhydrous gypsum (from 

 which the water has been expelled) and from 151 to 

 152 parts of gypsum as it is commonly found. 



The country adjoining the waters of the north east 

 branch of Susquehanna, are now supplied with gypsum 

 from the Genesee. This commerce began in 1811. 

 A set of people in the neighbourhood of Pine creek, 



