ECONOMIC GEOLOGY. 249 



LIME. 



The impure limestone of the coastal plains is burned for making lime at 

 many places near the towns, but nowhere in large quantities. Considerable 

 lime is used in the plaster with which many of the houses in the larger 

 towns are covered, and some is used also in mortar. The purer early Ter- 

 tiary limestones would doubtless yield a better grade of lime, but they 

 are now too inaccessible and too hard to quarry to be utilized. 



BRICK. 



The clayey alluvial soil of the flood plains of some of the rivers is suitable 

 for the manufacture of brick. Small amounts of brick are made near San 

 Pedro de Macon's and probably also near Santo Domingo City and else- 

 where. The methods used are crude and the brick is consequently not of 

 the best quality. Brick of better quality is reported to have been made by 

 the Spaniards, but some of the brick then used was probably brought from 

 Spain, so that it is not certain whether the brick found in the walls of old 

 buildings was made from native material or imported. 



GROUND WATER. 



Ground water is little used in the Republic. Some of the coast towns 

 have numerous wells, but most of them are shallow and the water in many 

 is brackish, perhaps because of the infiltration of sea water. Some of the 

 sugar companies near San Pedro de Macon's have put down wells a few 

 kilometers back from the coast, and have obtained water that is only 

 moderately saline. There are a number of wells in the rolling country 

 north of Santo Domingo City, some of them over 50 meters deep, which are 

 far enough inland to be unaffected by sea water. The following tables 

 show analyses of water from typical wells, springs, and streams in this area. 

 Although all the samples contain considerable amounts of dissolved salts, 

 some are good enough to be entirely suitable for many purposes. 



Mineral analysis and classification of spring water from Los Alcarrizos, 13 kilometers 

 north of Santo Domingo City. 

 [Sample collected by C. P. Ross in April, 1919. Analyst, Addie T. Geiger.] 

 „.. , Q .~ Constituents. Parts per ^ 



Silica (SiO) 03 



Iron (Fe) " 56 



Calcium (Ca) 190 



Magnesium (Mg) 2g 



Sodium and potassium (Na+K), calculated 4 q 



Carbonate radicle (C0 2 ) q 



Bicarbonate radicle (HCO3) 404 



Sulphate radicle (S0 4 ) n 2 



Chloride radicle (CI) 26 



Nitrate radicle (N0 3 ) 1 6 



Total dissolved solids 431 



Organic matter e 2 



