Examples from literature

• Borax is a mild alkaline body, and as a detergent is probably equivalent to a slight excess of caustic soda. 
• Next add caustic soda solution until the colour of the solution changes from yellow to red. 
• Permanent hardness in water, due to the presence of gypsum or sulphate of lime in solution, may be remedied by addition of caustic soda. 
• The bicarbonate of sodium settles out at once as insoluble crystals, easily removed, marketable at once as such, or easily converted into simple carbonate of sodium, and further into caustic soda, as in the ordinary "old" process. 
• The residue boiled with caustic soda would lose all its wool, which is soluble in hot strong caustic alkali.