X, A. 6 Cox and Dai' Juan: Salt Industry and Resources 383 



In certain localities as, for example, Pangasinan Province low 

 land below the tide level is used for evaporating salt water. In 

 this case the depression is leveled, inclosed by dikes, and filled 

 with tide water, which is evaporated by the sun's heat; when 

 the water has disappeared, the surface crust is gathered up and 

 leached as described previously. In this locality the leaching 

 apparatus is frequently a small banca, in which a hole has been 

 made at the bottom and covered with layers of straw and rice 

 husk. The concentration of the brine is determined by throw- 

 ing in it twigs of the guava tree. If they float, the brine con- 

 tains the required amount of salt to be boiled, but if they sink, 

 it is not yet sufficiently concentrated to be transferred to cauas 

 (kettles). It is saved for leaching fresh amounts of salt-im- 

 pregnated earth. The specific gravity of the first leachings, or 

 concentrated brine, called irna, as determined by means of guava 

 twigs, varies from 1.185 to 1.196. 



People from Ambos Camarines, Albay, Bohol, Batanes, Capiz, 

 Cagayan, Ilocos Norte, Ilocos Sur, Leyte, Misamis, Nueva Viz- 

 caya, Pangasinan, Surigao, Sorsogon, Samar, Union, Zambales, 

 and Mountain Provinces vary the process by evaporating to 

 dryness the brine of the final leachings in cauas, or huge, thick, 

 iron pans or kettles, mounted on rude clay furnaces. Sometimes 

 the process is much less refined. A fire is built on the beach, 

 and sea water is continually sprinkled on it, though not in such 

 quantity as to put out the fire. Finally the fire is allowed to 

 burn out, the ashes are leached, and the evaporation is made 

 by artificial heat as above outlined. The crystals produced by 

 boiling are formed rapidly and are, therefore, not so large, so 

 hard, nor so desirable for packing purposes as those produced 

 by slow evaporation. 



In Japan a plan somewhat different from the method just 

 described is employed.^^ The floor of the salt farm is made 

 perfectly level and is covered with an even layer of clay, which 

 is packed down and covered with a thick bed of coarse sand, 

 which is kept loose by frequent raking. The sand is irrigated 

 with sea water, led in through narrow ditches, which is allowed 

 to evaporate. The process is repeated until the sand has be- 

 come thoroughly impregnated with salt. The sand is then put 

 in filters, sea water is poured on, and the brine which filters 

 through is evaporated in pans over charcoal fires. 



It is of interest to note the great similarity of the processes 

 used in the Philippines for the manufacture of salt to the 



"Bull. La. Geol. Sur. (1907), 7, 195. 



