338 COX, REIBLING, AND REYES. 
TABLE [X.—Sand-lime bricks made with equal parts of Pasig and 
beach sand—Continued. 
v Molding pres- Density. Absorption after 24 hours in water. 
Mixture | sure in pounds 
No. per square 
| inch. Air dry. Dried at 110°. Air dry. Dried at 110°. 
9 7, 640 2.14 2.08 (art | 10.5 
| 9 10, 000 2.16 2.10 6.5 9.2 
Quingua sand.—North of Manila, the Quingua River con- 
tains an important amount of pebble sand which is similar to 
Pasig sand, except that the grains are harder and the quartz a 
little more abundant. The distance from Manila is considerable 
(about 35 kilometers), and although transportation by water is 
possible the river is often too shallow for navigation by launches. 
Transportation by rail is possible, but the present rates are pro- 
hibitive. This sand has not been tested, but its similarity to 
Pasig sand and greater content of quartz make it certain that 
it is equally as good, if not better. 
Tarlac sand.—Sand from the Tarlac River, at Tarlac, a station 
situated on the Manila and Dagupan railroad, appears to be the 
best sand-lime brick sand in Luzon. Owing to the large per- 
centage of quartz and clear glassy plagioclase feldspar, Tarlac 
sand-lime bricks have a pleasing grayish-white color, and take 
a good polish with a sparkling, granitic appearance. So far as 
we have been able to ascertain, there need be no efflorescence even 
when the percentage of feldspar is as high as in this material. 
The best results in our simple tests of the fire-resistant proper- 
ties of Philippine sand-lime bricks were obtained when Tarlac 
sand was used. Figs. 1 and 4, Plate VII, are photographs 
of sand-lime bricks made from mixtures 11 and 12, respectively, 
which remained sound after the fire test. Transportation from 
Tarlac to Manila must be largely by railroad, and the present 
high rates are prohibitive. 
TABLE X.—Tarlac sand and its efficiency as a sand-lime brick material. 
Content of silica. 
Soluble 
Paintin Soluble 
=, jin sodium 
chicne carbonate 
cacy). |X a2COs) 
Description and classification. 
Total 
Quartz. | Silica. 
Per cent. |'Per cent. | Per cent. | Per cent. 
A clean, sharp, mottled-gray sand which contains mag- 
netite, basalt, olivine, and about 50 per cent of clear, 
glassy grains readily mistaken for quartz, but which 
are in reality mostly plagioclase feldspars ~_____--__-__- 0. 06 11.82 2.91 66.07 
— 
