230 
The Philippine Journal of Science 
1919 
the regular way at the plant, however, it must have a sulphuric 
anhydride content of 1.80 per cent to insure a normal set. 
Considerable difficulty was experienced in controlling the gyp- 
sum content until many physical tests and chemical analyses 
had been made, and the limits of the sulphuric anhydride 
determined. 
The effects of exposure to air and of additions of hydrated 
lime are independent of the sulphuric anhydride content. 
Soundness is independent of the sulphuric anhydride content. 
Normal consistency is independent of sulphuric anhydride con- 
tent, but increases with the amount of hydrated lime present. 
Table I. — Setting time of cement ground in laboratory. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Fer cent. 
Mhi. 
Per cent. 
Min. 
Per cent. 
Min. 
Per cent. 
Min. 
0 
0 
0.71 
300 
1. 66 
330 
2. 79 
260 
0 
250 
0. 96 
200 
1.75 
160 
2.79 
340 
0 
270 
0. 96 
290 
1. 89 
220 
3.00 
160 
0 
270 
1. 00 
0 
1.89 
330 
3.20 
190 
0. 22 
80 
1.20 
200 
2.00 
120 
3. 63 
280 
0. 22 
180 
1.20 
310 
2.00 
250 
3.63 
350 
0. 25 
170 
1. 43 
210 
2.12 
220 
5.00 
170 
0. 46 
140 
1.43 
320 
2.12 
850 
9.10 
140 
0.46 
250 
1.60 
10 
2. 36 
260 
0. 50 
170 
1 50 
260 
2,35 
350 
0.71 
200 
1. 66 
190 
2.50 
80 
Table II . — Setting time of cement ground in plant. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Sulphur- 
ic anhy- 
dride. 
Initial 
set. 
Per cent. 
Min. 
Per cent. 
Min. 
Per cent. 
Min. 
Per cent. 
Min. 
Per cent. 
Min. 
1.35 
150 
1. 75 
20 
2.04 
150 
2. 25 
230 
2.44 
180 
1. 45 
0 
1. 76 
220 
2. 10 
140 
2.26 
130 
2.50 
130 
1. 45 
0 
1. 80 
0 
2. 11 
100 
2.27 
80 
2.50 
240 
1.45 
0 
1.82 
125 
2.11 
200 
2.28 
170 
2.61 
190 
1.50 
0 
1.87 
125 
2.13 
180 
2.29 
180 
2. 75 
240 
1.62 
0 
1. 87 
180 
2. 18 
250 
2.30 
140 
1.52 
160 
1.91 
130 
2. 19 
120 
2.31 
220 
1. 69 
0 
1.92 
180 
2.20 
130 
2. 32 
180 
1.61 
0 
1. 95 
180 
2.22 
110 
2.33 
170 
1.61 
0 
2.00 
110 
2.22 
160 
2.33 
230 
1. 62 
0 
2.00 
230 
2.22 
160 
2.36 
160 
1. 65 
10 
2.02 
140 
2.22 
200 
2. 36 
180 
1. 68 
0 
2.02 
170 
2. 23 
210 
2.39 
136 
1.74 
0 
2.03 
200 
2.25 
190 
2.41 
170 
