622 The Philippine Journal of Science mi 



is mined by open-cut methods and taken to the beach on a small narrow- 

 gauge railway. These two occurrences of rock asphalt near Baliti are 

 the only ones known in this general region. Seepages of petroleum and 

 leyteite occur a few miles north and northeast of Baliti. Pratt describes 

 these other localities in detail in * * * Phil. Jour. Sci. 10, Sec A 

 1915. 



The rock is dark brown, almost black. Its granular structure 

 is easily perceivable with the naked eye. The grains are so 

 thoroughly cemented that the rock is very hard to break in pieces, 

 even with the aid of a knife or a hammer. Nevertheless, it can 

 be crushed by means of the disintegrator and gives a slightly 

 sticky powder. The impregnation is not quite homogeneous. 



The chemical and physical examination of the rock must be 

 preceded by an inquiry as to the possible industrial utilization 

 of the material; the relative importance of the various tests is, 

 of course, dependent on the uses to which the material is destined. 

 Two possibilities of commercial utilization of the bituminous 

 rock must be considered : One is the separation of the bituminous 

 substance from the admixture of worthless sand which it impreg- 

 nates; the other is the utilization of the raw material, either in 

 the form in which it occurs or amended by the introduction of 

 more bitumen or sand. 



The extraction of bitumen is impracticable from the point of 

 view of treatment on a large scale. It would, of course, be 

 possible to extract the bituminous substance, particularly its 

 paraffin wax, by means of organic solvents such as, for instance, 

 hgnt petroleum ether; the expense, however, would be quite 

 prohibitive, as a very considerable portion of the solvent would 

 escape recovery. Boiling water is sometimes used in Europe 

 as a means of separating the bitumen in bituminous sand; this 

 treatment is founded on the principle that bitumens melt below 

 the temperature of boiling water and, as they are lighter than 

 water, they will float on the top of the liquid, while the sand, 

 being relatively heavy, will settle at the bottom. This treatment 

 does not succeed with the Leyte impregnated rock, as it is 

 mainly composed of carbonated lime, and bitumen is known to 

 adhere to calcium carbonate with an incomparably greater 

 tenacity than it does to silica when boiled with water. Dry 

 distillation is impracticable on account of the low percentage 

 of bitumen in the rock, which would necessitate the use of stills 



°l J e 7,i la / ge SiZe f ° r the Teco ™ r y ^ relatively small amounts 

 of distillate. 



One method of separating the bitumen from the mineral matter 

 deserves special mention. It is founded on the circumstance 



