Montana Gypsum Deposits — Rowe. 107 
time back, wagons were used in transporting the rock gyp- 
sum from the mines to the mill, but there was installed dur- 
ing the past summer a gravity tram car system which great- 
ly facilitates this part of the work and somewhat lessens the 
expense of transporting the raw material. The gypsum is 
dumped into an immense bin, and "directly from the rock 
bin" it is passed "through a 12x14 inch Blake crusher which 
crushes it to about one inch ; then through a Gates crusher, 
which reduces it to one-quarter of an inch ; then it is elevated 
to a trammel which separates the coarse from the fine, all 
over 40-mesh going down through a gravity pipe into a 
French burr which reduces everthing to 40-mesh or finer ; 
from the burr it is again elevated to the same separator, 
whence it travels by gravity to a bin over the calciner. The 
calciner holds about three tons and in this mechanism the 
gypsum is dehydrated by subjecting it to heat at 260 degrees 
Fahrenheit for two and one-half hours usually. From here 
the plaster of Paris is conducted to a storage bin where a 
retarder and hair are added, then through a Broughton 
mixer which finishes the stucco process. The capacity of 
the mill is thirty tons per day, of 24 hours, which it regularly 
turns out and loads directly in the railroad cars for shipment. 
More than one-half goes to Seattle and Spokane, the balance 
bemg marketed at Great Falls, Butte, Missoula, Helena and 
ether Montana towns. 
This mill is by far the better equipped and capacious of 
the two now operating in the state. 
Stucco or wall plaster from this mill was used in the 
Victoria Building, Spokane, Washington. 
State Capitol Building, Helena, Montana. 
U. S. Post OfBce Building, Butte, Montana. 
U. S. Post Office Building, Helena, Montana. 
Hennessey Merc. Co. Building, Butte, Montana. 
Court House Building, Great Falls, Montana. 
Court House Building, Kalispell, Montana. 
Masonic Temple Building, Butte, Montana. 
Yerrick Building, Missoula, Montana, and many others. 
The above readily shows that the Montana product is equal 
to the eastern product and is being quite generally used 
throughout the northwest. 
