266 The Philippine Journal of Science i9i6 



Table VIII. — Distillation products frotn heavy oil obtained from 

 bituminous mixture at outcrops L and M, Villaba, Leyte. 



Constituent. 



Per cent. 



Gasoline (below 150° C.) — 10.0 



Kerosene (150° to 300° C.) , 36.0 



Heavy oils (300° to 400° C.) [ 52.0 



Pitch residue (over 400° C.) - I 2.0 



The rock asphalt at N varies considerably in its content of 

 bitumen. Mr. Arguelles found in a sample from the lower beds 

 61.85 per cent of total bitumen, while two samples from the 

 upper part of the deposit, examined by Mr. Wells, yielded 6.30 

 per cent and 8.84 per cent of the total bitumen, respectively. 

 The sample richest in bitumen contained only 0.13 per cent of 

 paraffin scale. The strikingly lower paraffin content of the bi- 

 tumens from outcrops D and N as compared with the bitumens 

 from the other outcrops may be due to the fact that the bitumens 

 at D and N have migrated through porous or broken rocks, while 

 elsewhere the bitumens have simply occupied open spaces in the 

 rocks. That is to say, the paraffin might have been removed 

 by the filtering effect of the diffusion of the original petroleum 

 through porous rocks. 



SOURCES AND PROBABLE QUANTITIES OF PETROLEUM AND 

 RESIDUAL BITUMENS 



The source of the residual bitumens in Leyte is undoubtedly 

 the petroleum with which they are associated. Natural bitumens 

 are universally conceded to have their origin in petroleum, being 

 formed through the elimination of the more volatile constituents 

 and the concentration and metamorphism of the heavier hydro- 

 carbons. The bitumens in Leyte form so nearly a continuous 

 series from petroleum to solid coallike bitumen and are so like 

 the base of the Leyte petroleum in their constitution that the 

 relation of one to the other would be clear without the necessity 

 of drawing analogies from what has been learned concerning 

 other natural bitumens. 



The source of the petroleum in Leyte is probably the Vigo shale, 

 just as the Vigo shale appears to be the source of the petroleum 

 in the Tayabas field, where the essential conditions are similar 

 to conditions in Leyte. Possibly some of the Leyte petroleum 

 originates in the Canguinsa, although the fact that petroleum and 

 residual bitumens are found in the Canguinsa at present may be 

 explained otherwise. In all the observed occurrences of petro- 



