370 
CEMENT MATERIALS AND INDUSTRY. 
Analyses of slag cements. 
Lbull. l*43. 
Silica (SiOj) -- 
Alumina ( A1 2 3 ) 
] it >n oxides (FeO,Fe 2 3 
Lime (CaO) 
Magnesia (MgO) 
Sulphur (S) 
Sulphur trioxide (S0 3 ) 
Loss on ignition 
19.5 
17.5 
n. d. 
54.0 
n.d 
n.d 
n.d 
n.d 
30.56 
13. 31 
0.25 
45.01 
2.96 
04. 63 
&1. 41 
n.d. 
22.45 
13.95 
3.30 
51. 10 
1.35 
0.35 
7.50 
27.20 
14.18 
50. 03 
3.22 
0.15 
4.25 
28.40 
12.80 
51.50 
n.d 
1.40 
28. 95 
rll.40 
I 0.54 
50.29 
2.96 
1.37 
n.d. 
3. 39 
29.80 
12.30 
51. 14 
2.34 
1.37 
2.60 
8 9 10 
27.80 
11.10 
50.96 
2.23 
1.18 
5.30 
27.0 
12.0 
55.0 
n.d. 
n.d. 
n.d. 
27.78^ 
11.70 
51. 71 
1.38 
1 . 31 
n.d 
" Equals CaS. 
b Equals CaS0 4 . 
1. Choindez, Switzerland. 
2. Bilbao, Spain. 
3. Saulnes, France. 
4. 5, 6, 7, 8, Chicago, 111. 
9. North Birmingham, Ala. 
10. Enslev, Ala. 
IDENTIFICATION OF SLAG CEMENT. 
Slag cements may usually be distinguished from Portland cements; 
by their lighter color, inferior specific gravity, and slower set. They 
show on analysis lower lime and higher alumina percentages than Porti 
lands, and usually contain an appreciable amount of calcium sulphide. J 
Owing to the presence of this last-named constituent, a briquette* 
of slag cement left for some days in water will show upon fracture a 
decided greenish tint. If it has been exposed to salt water, this tinti 
will be much more marked and the odor of hydrogen sulphide will bet 
observed. Two things should be noted, however, in this connection: 
Though sulphides are usually present in slag cements they are noti 
necessary constituents of them, and, on the other hand, sulphides are> 
occasionally present in Portland cements, being formed from the sul- 
phates in case the flame of the kiln is not sufficiently oxidizing. 
Color. — Slag cements are usually much lighter in color than the 1 
Portlands, varying from a bluish white to a light yellow. The colon 
of the cement depends partly upon the color of the slag and the lime, 
but more largely upon the relative proportions of the two ingredients. 
Slag cements do not stain masonry, in which respect they have an 
advantage over Portlands for certain uses. 
Specific gravity. — Cements of this class are lighter than Portlands, 
their specific gravity usually ranging from 2.7 to 2.8. This gives 2 
greater bulk for the weight, but, on the other hand, it reduces then 
density of the set cement, which is not desirable for some purposes. 
JBapidity of set. — Normally slag cements are slower setting thai 
Portlands. Whether this property is a disadvantage or not wil! 
