160 ^he Philippine Journal of Science 1914 



in chemical composition and in fineness of grain. On the 

 other hand, the chalk requires slightly more clay for a proper 

 cement mixture, and must be hauled a short distance (600 

 meters) to the mill site while the other rock lies practically on 

 the mill site. Good cements have been made from each class 

 of material and from mixtures of the two classes of material. 



Limestone 46 must be transported about 2 kilometers; it is 

 hard, and quarrying relations are not favorable. Owing to 

 its composition, a large proportion of clay materials must 

 be added to it to produce a Portland cement raw mixture. 

 Because of this requirement, limestone 46 cannot well be used 

 with tuff 47 which is too siliceous to be added in large proportion 

 to a cement raw mixture, and since tuff 47 is the most desirable 

 of the available clay materials limestone 46 cannot be considered 

 as favorably as limestones 35, 37, and 39 which can be used 

 with tuff 47. The same objections may be made to the use of 

 limestone 51, with added emphasis as to unfavorable quarrying 

 relations and as to the length of the required haul, which in this 

 case would be about 7 kilometers. 



Siliceous material 47, a volcanic tuff, is preferable to the other 

 siliceous materials by reason of the shorter transportation which 

 its use would involve and the uniformity in its physical and 

 chemical character. It could be quarried as cheaply as either 

 of the other available siliceous materials, and for use with the 

 best calcareous materials its composition is at least equally suit- 

 able. Siliceous materials 48 and 49, which are clastic sediments, 

 are objectionable chiefly because of their nonuniform chemical 

 and physical characters. The expense of quarry operation would 

 be about equal to that required for material 47, but the cost of 

 transportation would be greater because material 47 is less than 

 half as far from the proposed mill site. Siliceous material 51, 

 a shale, is constant in physical character but varies in chemical 

 composition. Like materials 48 and 49, it would be quarried 

 cheaply, but it is at an even greater distance (9 kilometers) from 

 the mill site. 



The experimental results of Reibling and Reyes show that 

 calcareous materials 35, 37, and 39 and siliceous material 47, 

 which are considered most favorable from the viewpoint of field 

 relations, are likewise most desirable from the viewpoint of 

 ease of manufacture and excellence of the product. This being 

 the case, the other materials tested lose their importance, while 

 at the same time the feasibility of cement manufacture at Naga 

 is established both by the study of the field relations and the 

 burning tests on the raw materials. 



