48 THE WEALTH OF THE SEA 



These ponds are floored with smooth broken pot- 

 tery, set in lime mortar to retard seepage and to 

 prevent the admixture of sand with salt, and are 

 surrounded with bamboo fences covered with grass 

 to prevent the wind from blowing dust into them and 

 to keep the floating crystals from congregating on 

 the leeward side. More brine is added as required. 

 When salt begins to crystallize out, the crystals are 

 raked into heaps every day after sundown, gathered 

 into baskets to drain, and finally conveyed into ware- 

 houses. In some parts of the Philippine Islands and 

 in Japan, this simple, picturesque method is modified 

 by evaporating the leachings in pans or kettles over 

 fires built in furnaces. 



In China most of the solar salt is made by the 

 simplest possible process, employing methods which 

 have been used without change for a thousand years 

 or more. In fact, there is no record to show just when 

 the salines were established. The salt is made by 

 solar evaporation of sea-water without any attempt 

 at the separation of the impurities. Sea- water is 

 pumped into large evaporation basins by means of 

 windmills. The basins are constructed along the 

 sea-coast and resemble innumerable tennis courts of 

 great size ; they are arranged in groups, so that sev- 

 eral may be filled by a central pump. These basins, 

 which are constructed by leveling the ground and 

 rolling it with a stone roller until it is hard, are 

 separated from each other by ridges of mud about 

 eight inches high. Two or three inches of sea-water is 

 pumped into the ponds; this evaporates in about a 

 week, leaving a coating of salt on the bottom. After 



