Japanese Salt and Foreign Salt

Together with air and water, salt forms a part of the vital triad of substances essential for the maintenance of life.
The human body incorporates a certain percentage of salt which plays a critical role in controlling and regulating the water content of living tissues and cells.
At a very early stage in history, long before the chemistry of salt was understood, our remote ancestors were already aware of its importance for the maintenance of life and health; the origins of salt manufacture and the salt trade appear to date back to the most primitive stages of human civilization.
Natural salt is found in several forms, each of which calls for different production techniques. In many parts of the world, rock salt occurs, often in massive underground, deposits while saline lakes and salt-flats on the sites of former salt-lake beds also provide plentiful salt supplies in some countries. In warm or tropical coastal areas with relatively low humidity, salt is often extracted from sea water through natural evaporation.
In comparison with other heavily populated parts of the world, Japan has always been at a disadvantage, for it has no known rock-salt deposits or other terrestrial salt sources, while its relatively low median temperatures and heavy rainfall make reliance on natural evaporation impracticable.
Until relatively recent times, importation of salt from abroad was difficult if not impossible, due to the island nation's distance from the continent.
Thus, Japan was forced to develop its own salt technology, some aspects of which are not found elsewhere. In general, Japanese salt production was carried on in two stages. First, various methods were utilized to produce a heavily condensed saline solution from ordinary sea water; in the second stage, this salt concentrate was boiled down to yield a residue of edible sea salt.
Even with the universal mechanization in use today, these two processes still form the groundwork of salt manufacture in Japan; the search for increased efficiency in extracting salt from sea water continues to challenge the ingenuity of contemporary scientists and technicians. The scope of their research is not limited to edible salt production alone, for the growing significance of soda and soda derivatives in modern industry has, if anything, increased the importance of salt as one of the indispensable raw materials necessary for today’s advanced technology.