The soda carbonate may also be added to soap as a solution of soda ash (58° alkali) either concentrated, 62° Tw.
This is made as follows: a soda ash liquor of about 15° to 20° Tw.
The alkali is sold in various forms as soda ash, soda crystals, washing soda, etc.
Both of these materials are required in the manufacture of soda ash.
There is no advantage in using caustic soda in this preliminary boil, soda ash being just as effective and cheaper.
Fillers in varying proportions may replace the soda ash in the above formulae.
The cheapest and most universally used for this purpose are soda ash and caustic soda.
Half the water is run into the kettle, boiled, and then the soda ash and half the salt added.
Then Detroit makes great quantities of soda ash and alkalies.
Soaps made from "soda ash," as nearly all hard soaps are, tend to dry and harden the skin, and if used often produce bad effects.