386 



The Philippine Journal of Science 



1915 



Table II. — Shoiving the magnesia and lime content of Philippine salt. 



[Numbers give percentages.] 



Source. 



Calcium 

 oxide 

 (CaO). 



Magnesi- 

 um oxide 

 (MgO). 



Remarks. 



Paranaque (1) (1911) 



0.96 



1.24 



1.66 

 0.79 

 0.33 

 0.70 

 0.78 

 0.34 

 0.47 

 6.14 

 4.03 

 trace 

 0.55 

 1.74 



0.85 



0.&4 



1.93 

 1.81 

 0.33 

 0.45 

 0.39 

 0.73 

 0.67 



trace 

 1.43 

 0.25 



trace 

 0.50 



Prepared from estero water. Filipino 



method. 

 Prepared from estero water. Chinese 

 method. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Salt spring. 



Do. 



Do. 



Do. 



Do. 



Paranaque (2) (1911) 



Malabon (1911).. 



Obando (1911) 



Obando (1) (1913) . 



Obando (3) (1913) 



Obando (4) (1913) 



Obando (5) (1912) 



Obando (6) (1912) 















pond at a density never greatly exceeding 1.13, the concentration 

 at which gypsum begins to deposit, which is too soon. Fig. 5 

 gives the concentrations of the brine of a plant in actual opera- 

 tion. The effect is readily noticeable on the composition of the 

 product, which contains a high percentage of lime. The bitter 

 salts are not removed from many of the crystallizing ponds, 

 and the effect is evident in the high magnesia content of the 

 salt. The lower magnesia content of the Parafiaque sample 

 given in Table II is due to its being an early crop before the 

 bitterns had become greatly concentrated. 



The salt produced by the old Filipino method has acquired 

 a reputation for its superior qualities for curing fish. Many 

 a Filipino will say that it takes more of the salt produced by 

 the new, or Chinese method, to preserve a given weight of fish. 



In the old process the water is evaporated to dryness, and 

 gypsum, which is not readily soluble, is largely eliminated, for 

 only a small amount of it is redissolved in the leaches. In this 

 way the separation is more complete than is now common prac- 

 tice in the new method, where the brine is transferred to crys- 

 tallizing ponds too soon. By the old method, particularly, 

 the salt was usually retained in warehouses for some time. 

 With the new method salt is produced in large quantity and 

 is frequently sold directly after draining and before the pile 

 has weathered and the hygroscopic salts have been washed out 

 by the absorption of moisture from the air. These differences 



