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STATE GEOLOGIST. Boll 
In volume VIII, Michigan Geological Survey, the following figures 
are given regarding the cost of making cement in a marl and clay in- 
stallation, by the wet process: the burning is estimated at 17.2 cents per 
barrel, the clinker grinding at 8.8 cents, the power at 9.3 cents and the 
packing at 2.55 cents per.barrel. The average cost of making cement 
in Michigan is estimated at 68 cents per barrel. | 
OHIO PORTLAND CEMENT PLANTS. 
The writer has visited all the cement plants of Ohio with one ex- 
ception and was received with courtesy and consideration in every plant 
visited. The pioneer plant of the State is that of the Sandusky Portland 
Cement Co., at Bay Bridge. Permission to visit this plant was refused, 
hence no description can be given of its equipment or arrangement. 
The largest cement works of the State, the Castalia Portland Cement 
Co., is located at Castalia, 6 miles south of Sandusky, in Erie county. 
The raw materials are a very pure travertine, and a soft clay. The 
travertine is the only deposit of the sort worked in the United States. 
The wet process is used, the materials being run through a wet plan and 
tube mills. After being ground the slurry is pumped into large tanks by 
means of compressed air and the composition corrected by the addition of 
high lime or high clay correction slurry. The burning is done in 13 rotary 
kilns. The clinker is ground in ball and tube-mills, and two Griffin 
mills are also installed. The coal is ground in Griffin mills. The power 
available is 1,700 horsepower. The average capacity is 1,500 to 1,600 
barrels of high grade cement. A view of this plant will be found on 
page 332, for which the writer is indebted to the company. The offices 
ot the company are at Pittsburg, Pa. 
In Stark county, at Middle Branch, we find the Diamond Portland 
Cement Co. using the Putnam Hill limestone and the shale associated 
with it, of which, however, part is rejected and dumped. This mill has 
a capacity of about 600 barrels per day, using 8 to 10 feet of the shale 
and 6 to 7 feet of the limestone. The limestone is crushed by Aultman 
rock crushers and then passes through a rotary dryer, roller crushers, 
and is ground fine by Emery mills. It is then stored in large tanks, 28 
feet by 10 feet, being thoroughly sampled in these and analyzed. 
The shale is put through a dry pan, a rotary dryer, and is ground 
fine like the limestone and is also stored in large tanks where its average 
composition is determined. The limestone and shale are then weighed 
out by means of a bucket and crane and ground together in large ball-mill 
mixers. The mixture is hence positive and is bound to be correct. 
dhe mixed constituents are then conveyed to a large storage 
tank, which feeds a pug-mill and auger brick machine where stiff mud 
bricks are made and stacked on iron cars. These are run on tracks 
into a steam tunnel dryer and dried thoroughly. The dried bricks are 
