THE MINING AND QUARRY INDUSTRY I90S 31 



cement makers who prefer to use the material in that form. For 

 agricultural purposes the gypsum is always ground to a very tine 

 product which is marketed under the name of land plaster. The 

 manufacture of calcined plasters calls for the greater part of the 

 output of g}psum at the present time. By calcination the gypsum 

 is converted into plaster of paris or stucco in which form it is 

 used largely as a structural material, also for casts, molds and in 

 plate glass manufacture. The calcination is performed generallv 

 in vertical kettles, covered at the top, and provided with mechanical 

 stirrers for keeping the material in constant motion so as to pre- 

 vent overburning. In one or two of the more recently erected 

 plants, the calcining process is carried out in a rotary kiln of the 

 Cummer type, which has an important advantage of being con- 

 tinuous in its work. For plaster of paris the temperature of burn- 

 ing does not exceed 350° to 380° F. as a maximum. Wall plasters 

 and cement plasters are made from plaster of paris by addition 

 of some organic or mineral substance which serves to retard the 

 setting process. Wall plasters may also contain some fiber, such 

 as hair, fibrous talc, or a wood liber made from basswood or wil- 

 low. A product known as wall board consists of layers of paper 

 smented with plaster of paris, forming thin sheets which can be 

 nailed to the studding and joists of buildings in the place of lath 

 and which are then covered wdth a coat of plaster. 



The manufacture of gypsum products is carried on in the State 

 bv other than the producing companies, and there are a number of 



ants that make wall plaster, etc. from gypsum purchased from 

 v.ie local mines or imported. The imported g}psum comes mostly 

 from Nova Scotia. Xo attempt to secure information of such oper- " 

 ations has been made in connection with this report. 



The mining companies w'ho are engaged in the calcined plaster 

 trade have plants in Syracuse and vicinity; at Wheatland and 

 Garbutt, Monroe co. ; Oakfield, Genesee co. ; and Akron, Erie co. 



Production and trade. The market conditions last year were 

 rather poor, with a recession in both demand and prices. The de- 

 crease in Portland cement production afYected the trade to some 

 extent, while the falling ofif in building operations was an adverse 

 factor in the calcn-;ed plaster industry. However, the production 

 of crude gypsum showed only a small loss as compared with the 

 record output of 1907. The total reported by the mining com- 

 panies was 318.046 short tons against ^2^,t;2T, short tons in 1007. 

 a decrease of ^2yy tons, or less than 2 per cent for the year. The 



