282 CEMENT MATERIALS AND INDUSTRY. [bull. 243 1 
a natural cement of the following* composition had been made fron 
this rock: 
Analysis of natural cement, K 
ngs Rock, Pa. 
Silica (Si0 2 ) 
" 28. 1 I 
Alumina ( A1 2 3 ) 
9. 1" I 
Iron oxide ( FeO ) 
3.2 
Lime (CaO) 
53.3 
Magnesia ( MgO ) 
i.o| 
Alkalies (K 2 0, Na 2 0) 
2.8' 
Water and loss 
2.4 
Such an analysis of a natural cement would imply that the rock f roc j 
which it was made was closely similar in 
composition to the cemen 
rock of the Lehigh district, and that the addition of 10 per cent or s< 
of pure limestone would give a good Portland cement. 
CARBONIFEROUS LIMESTONES 
DISTRIBUTION. 
Geologic group. 
Name of limestone. 
Thick- 
ness. 
Stratigraphic position. 
Dunkard formation or 
Upper Washington 
Feet. 
30 
At top of Washingto ) 
Upper Barren meas- 
limestone. 
formation, 250 to 42:1 
ures. 
feet above the Waynes <i| 
burg coal. 
Monongahela forma- 
Waynesburg limestone . 
35 
20 feet below the WaynJJ 
tion or Upper Pro- 
burg coal. 
ductive Measures. 
Benwood or Great lime- 
73 
120 feet above the Pitt J 
stone. 
burg coal. 
Sewickley or Fishpot 
30 
100 feet or more above thij 
limestone. 
Pittsburg coal. 
Redstone limestone 
10 
60 to 100 feet above tt ( 
Pittsburg coal. 
Conemaugh formation 
Pittsburg limestone 
12 
20 feet below the Pittsbuj n 
or Lower Barren 
coal. 
measures. 
Elk Lick limestone 
6 
Between Pittsburg and U] \] 
per Freeport coal. 
Ames or Crinoidal lime- 
8 
Do. 
stone. 
Allegheny formation 
Upper Freeport* lime- 
28 
Belo w Upper Freeport coa 
or Lower Productive 
stone. 
measures. 
Lower Freeport lime- 
5 
Below the Lower Freepo | 
stone. 
coal. 
Johnstown limestone . . . 
10 
Below the Upper Kitta 1 
ning coal. 
Vanport or Ferriferous 
20 
Below the Lower Kitta: 1 
limestone. 
ning coal. 
Pottsville formation . . . 
UpperMercer limestone. 
4 
Lower Mercerlimestone. 
3 
Mauch Chunk forma- 
Greenbrier or Mountain 
30 
tion. 
limestone. 
Pocono formation 
Siliceous limestone 
60 
Benezette limestone 
7 
