oxalic acid

oxalic acid (uncountable)

1. (organic chemistry) A colourless, crystalline dicarboxylic acid, (COOH)₂, found in rhubarb, spinach and other plants, often as crystals of the calcium salt.
   • 1880, William Blades, The Enemies of Books, page 92:

     If not sufficiently purified, a little hydrochloric or oxalic acid, or caustic potash may be put in the water, according as the stains are from grease or from ink.

• acid of sugar (obsolete)
• ethandioic acid

• oxalate