256 
CEMENT MATERIALS AND INDUSTRY. 
[BULL. 24: 
Dr. George Duryee, of New Jersey. In October, 1888, one kiln wa 
put into operation at the South Rondout works. This kiln was 5 1 
feet long and 50 inches in diameter. The upper end was at first mad! 
50 inches higher than the lower end, but later this was reduced to 3 il 
inches. On trial this was found to be a very satisfactory method c | 
burning, the one kiln handling all the material the mill could suppll 
and producing a uniform and high-grade product. Of still greater 
importance was the fact that it was found possible to charge the mixe : 
and ground raw material directly to the kiln without preliminar 
wetting, making into bricks, and drying. This was the first America i 
plant at which this practice of direct charging was followed. 
In 1889 the plant was entirely destroyed by fire, and Portland cemei| 
manufacture in the lower Hudson Valley ceased till 1900. 
The following notes from the Rondout records establish some date- 
October 25, 1888. — Burned about 100 barrels to-day; oil fuel. Ground the limn 
stone and clay separately dry, and mixed before feeding to kiln. Mixture — clay, 
pounds; limestone, 80 pounds. 
February 25, 1889. — Mixture burned — clay, 21 pounds; limestone, 100 pounds. 
Analysis of resulting cement. 
Lime 65. ! 
Silica : 18. 
Alumina and oxide of iron 11. 
Potash 
Soda 
Carbonic acid 
Magnesia and undetermined 2. 
100. 
Physical tests of tensile strength. 
7 days =253 pounds. 
14 days=466 pounds. 
Second tests: 
7 days =306 pounds. 
10 days=509 pounds. 
Representative analyses of the limestone and clay used at the Cz 
thage Landing and South Rondout plants are as follows: 
Analyses of limestone and clay used for cement making. 
Lime 
Magnesia 
Peroxide iron 
Alumina 
Silica 
Carbonic acid 
Water and alkalis 
Limestone. 
52. 295 
.5 
.438 
.677 
4.405 
41.515 
.17 
100. 00 
Clay 
1. 
2. 
9. 
20. 
54. 
12. 
100. 
