REPORT OF TPIE DIRECTOR AND STATE GEOLOGIST 1903 137 



require the longest time for setting show the greatest strength. 

 This seems to give some ground for the supposition that retard- 

 ing the set does not decrease the strength. It also shows that a 

 material which of itself may not be as strong as the material 

 whose set is to be retarded, may give increased strength to the 

 retarded material. 



Accelerators. It is sometimes necessary to hasten rather than 

 retard the set of plaster, and in order to do so, some other crystal- 

 lizing salt as alum or borax is added in small quantity to the 

 plaster. When moistened, this salt has a tendency to crystallize 

 and starts that process in the plaster of paris. A dish which 

 has been used in making plaster of paris will have a tendency to 

 accelerate the set because of the crystals already formed. 



New York mines and mills 



Cottons. At Cottons an open quarry is worked by Mr R. D. 

 Button. Ordinary black powder is used as the explosive, and 

 the entire output is used in the manufacture of land plaster. 

 An analysis^ of the rock follows : 



Sulfate of lime (pure gypsum) 



82.66 



Carbonate of lime 



6.569 



Carbonate of magnesia 



5.075 



Iron oxid and alumina 



1.837 



Insoluble matter and moisture 



3.859 



100 



The greater part of the rock is ground at Perryville by Mrs 

 Hattie C. Hodge. 



Fayetteville. The quarries at Fayetteville are located about 2 

 miles southwest of the village and are situated on two knolls. 



Four companies have quarries here: the National Wall 

 Plaster Co. and the Adamant Wall Plaster Co. of Syracuse, Mr 

 F. M. Severance and Mr C. A. Snooks of Fayetteville. 



All these quarries were at one time owned by the Onondaga 

 Gypsum Co., which was formed in 1878 and operated as a plaster 



'Analysis furnished by R. D. Button. 



