Ferric hydrate, iron soaps and all insoluble impurities are precipitated.
Soaps give an alkaline reaction and have a decided acrid taste; in a pure condition - a state never reached in practice - they have neither smell nor colour.
Almost without exception potash soaps, even if made from the solid fatty acids, are " soft," and soda soaps, although made with fluid olein, are " hard "; but there are considerable variations according to the prevailing fatty acid in the compound.
Almost all soda soaps are precipitated from their watery solutions by the addition of a sufficiency of common salt.
Ammonia soaps have also been made, but with little commercial success; in 1906 H.