Question

why modified solvary process is also known as dual salt process

Answer 1

here is ur answer....
The Solvay process or ammonia-soda process is the major industrial process for the production of sodium carbonate (soda ash). The ammonia-soda process was developed into its modern form by Ernest Solvay during the 1860s. The ingredients for this are readily available and inexpensive: salt brine (from inland sources or from the sea) and limestone (from quarries)