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Because the ashes of these sodium-rich plants were noticeably different from ashes of timber -used to create potash-, they became known as "soda ash". Historically it was extracted from the ashes of plants growing in sodium-rich soils, such as vegetation from the Middle East, kelp from Scotland and seaweed from Spain. Sodium carbonate is well known domestically for its everyday use as a water softener. It has a strongly alkaline taste, and forms a moderately basic solution in water. Pure sodium carbonate is a white, odorless powder that is hygroscopic -absorbs moisture from the air. It most commonly occurs as a crystalline decahydrate, which readily effloresces to form a white powder, the monohydrate. Sodium carbonate: Sodium carbonate, Na2CO3, -also known as washing soda, soda ash and soda crystals, and in the monohydrate form as crystal carbonate- is the water-soluble sodium salt of carbonic acid.
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