18 MARINE PRODUCTS OF COMMERCE 



rated suflBciently to deposit salt, the crystals are raked into piles every day after 

 sundown and then gathered into baskets to drain. 



The Oriental Solar Process. In China the simplest possible process of manu- 

 facturing solar salt is employed. Although there is no record to show just when 

 the salines were established, the identical methods are known to have been in 

 use for a thousand years or more. The salt is made by the solar evaporation of sea 

 water without any attempt at the separation of the impurities from the sodium 

 chloride. The process is essentially as described in the following: 



Sea water is pumped into large evaporating basins by means of windmills. 

 These basins, resembling innumerable tennis courts of great size, are constructed 

 on the flats along the seacoast by leveling the ground and rolling it hard v^dth a 

 stone roller. They are separated from each other by low ridges of mud about 8 

 inches high and are arranged in groups so that they may be filled with a central 

 pump. About 3 inches of sea water are pumped into the basins and allowed to 

 evaporate, leaving a coating of salt on the bottom by the end of a week. This 

 salt is scraped into a pile and shoveled into small boats. The bottom of the basins 

 is then rolled again, more sea water pumped in, and the salt making continued. 

 The basins are connected by means of small canals to the main salt yards which 

 are either near a railroad or a river. The salt is stored at the salt yards in great 

 heaps which are usually covered with mats. 



The Improved Oriental Process. In some sections of China, Japan, and the 

 Philippines solar sea salt is produced by a process resembling the European inas- 

 much as the sea water is first allowed to settle and concentrate in ponds until 

 it is nearly saturated, and is then run into crystallizing ponds where the salt 

 crystallizes from the brine. The preliminary evaporation which takes place in 

 the crystallizing ponds permits the sediment to settle and also causes the precipita- 

 tion of iron sulfide, calcium carbonate, and most of the calcium sulfate. Since 

 the concentrated brine is allowed to evaporate to complete dryness, the salt pro- 

 duced is high in calcium and magnesium chlorides. 



The European Solar Salt Process. The greater proportion of the world's pro- 

 duction of sea salt is manufactured by the European solar process. Practically 

 all the sea salt produced in Europe, the West Indies, South America and Africa 

 is made in this manner. This process is a decided improvement on the ancient 

 oriental solar process as the product contains less impurities. The chief countries 

 of Europe which produce solar sea salt are France, Spain, Portugal, and Italy. The 

 customary procedure followed in manufacturing salt by this method will now be 

 described. 



The salines or salt farms are laid out on low-lying flat land adjoining a bay or 

 the ocean. The flats are enclosed by high dykes to prevent flooding from high 

 sea or storms. Each "salt meadow" is subdivided by internal walls into compart- 

 ments of different levels. One end of the salt farm is usually slightly higher than 

 the other so that the brine may flow from one compartment to the other. When 

 the dry season begins, sea water is either pumped or admitted through a canal 

 at high tide into the higher compartment and allowed to stand in the concentra- 

 tion pond until the clay and other suspended matter settle. A preliminary evapora- 

 tion takes place during the clarification. The concentrated, clarified sea water is 

 then run out into shallow reservoirs where it remains until it reaches 23-25° Be. 

 (1.178-1.196 sp. gr.). By the time the brine has reached this density, the iron 



