The advancements in the chemistry allowed to produce the salt effectively.
As a result, the salt was easily manufactured in the factories. Earlier, the salt was extracted from oceans, which was a time taking and very difficult process. Due to easiness in the manufacturing of the salt, the availability of the salt was increased. The increase in availability of the salt made by factories, allowed more supply of the salt in the market and the prices of the salts were drop down to a significant level.