XIV, 5 Dar Juan and Elicano: Philippine Glass Materials 477 
In experimental tests made in the Bureau of Science, the 
quartzose beach sand and the vein quartz gave glass very sim- 
ilar in quality, except that that made from the vein quartz is 
of a lighter color due to a lower iron content, as shown in Table 
IV. The materials being of equal manufacturing suitability, the 
quartzose beach sand is preferable for the following reasons: 
1. The quartzose sand already contains some feldspar, which 
lowers the melting point and supplies to the charge a certain 
amount of lime, alumina, and alkalies; while, if the vein quartz 
is used, all the fluxes have to be added. 
2. The individual grains of the quartzose sand do not exceed 
3 millimeters in diameter and thus, as a natural product, this 
sand can be readily charged into the furnaces. The vein-quartz 
gravel or bowlders, or the materials quarried from the veins, 
will necessarily have to be subjected to quenching, pulverizing, 
and sieving, which will increase the cost of manufacture. 
3. The cost of mining sand is very much cheaper than vein 
quartz. The former can be readily dug from the beach and 
loaded into boats, while in the case of the vein quartz blasting 
and mucking will have to be done. The vein-quartz gravel of 
small size already mentioned as accumulated along the beach is 
not inexhaustible. 
It has been stated above that a sand concentrate, averaging 
2.5 meters wide and composed mainly of quartz grains, is found 
along the beach between high- and low-tide levels. It is con- 
sidered that this supply of concentrate is inexhaustible on 
account of the continuous concentrating action of the waves on 
the adjacent deposit of impure sand, which readily and con- 
stantly supplies pure sand. 
V/ith an average width of 2.5 meters and a depth of 1 meter, 
extending 5 kilometers in length on both Looc and Tabahin 
Bays, there is ready on hand a supply of sand concentrate meas- 
uring 12,500 cubic meters. By actual test, a cubic meter of the 
sun-dried sand weighs approximately 1.5 metric tons. This 
indicates that there is available a supply of about 18,750 metric 
tons of sand, which will last a factory, with a daily capacity of 
5 tons, twelve and one-half years of three hundred working days 
a year. It is presumed that after the twelfth year digging may 
again be done on the original place, and a concentrate be found 
of similar quality as before. 
From data now on hand it is not possible to estimate accurately 
the cost of equipment for a glass factory of a given capacity, 
but any technical information or suggestions as to manufacture 
can be furnished to prospective investors. 
