Caustic soda (Sodium hydroxide) is achromatic and transparent
solution, its proportion is 1.**1. The solid Sodium hydroxide is
white solid or pieces, its proportion is 2.*3, show alkali
character, having strong causticity to skin, weaves and sheet. In
the air it will absorb the carbon dioxide and change into sodium
carbonate. The solid Sodium hydroxide has strong moisture
absorption character, so it must stored protecting against the tide
and isolating air.
