REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1900 rl79 



At the mill of the National plaster co. the Cummer process is 

 used for calcining the gypsum. This process consists in crushing 

 the gypsum rock in a Blake crusher to about the size of hickory 

 nuts. This material is then taken to a cylinder about 27 feet 

 long by 4 feet in diameter, which revolves over a fire. The smoke 

 is carried through the cylinder so as to utilize all the heat avail- 

 able, and is then taken off by a flue. This cylinder is inclined 

 slightly so that the material runs from one end to the other. The 

 temperature at which the gypsum is calcined, ranges from 600° 

 to 800° F. From the calciner the material is taken to a large 

 cooling bin made of brick. This bin is about 30 feet long by (j 

 feet wide, by 20 feet high. The heat then permeates the entire 

 mass of rock, calcining the inner portions of the small pieces. 

 The material is drawn from the bottom of the cooler through 

 gates and taken by a worm conveyer to the mills, where it is 

 ground. It is then taken to the storeroom and put in bags for 

 shipment. 



The capacity of the mill is 50 tons a day. The annual produc- 

 tion is about 50,000 tons a year. This calcined gypsum is 

 shipped, to a considerable extent, to cement manufacturers, and 

 is utilized by the National wall plaster co. for the manufacture 

 of hard finish. For the manufacture of hard finish, it is mixed 

 with certain proportions of sand, clay and a patent retarder. 



On the east of the National wall plaster co.'s beds and south of 

 those owned by Mr Severance is located the property of the Ada- 

 mant wall plaster co. It owns about 19 acres of ground, about 

 15 of which is underlain by gypsum. This property is not at 

 present worked, but will be opened up this coming year. An 

 old quarry is located at this point, but has not been worked for 

 some years past. At present the Adamant wall plaster co. is 

 using calcined plaster from Oakfield N. Y., and calcining Nova 

 Scotia gypsum. It uses in its wall plaster about one half sand, 

 Sfo to 10^ of clay and asbestos, and about 40^ of calcined gypsum. 

 In the manufacture of hard finish about Ifc of ground talc is 

 used as a whitener. The retarder is a trade secret. 



The annual production is about 100,000 to 150,000 bags of 120 

 pounds a year. 



