With the addition of oxalic acid, the yttrium oxalate precipitates. The acid when fused with caustic alkalis yields oxalic acid. Citric and oxalic acids are used as rust removal. The toxicity of ethylene glycol comes from its metabolism to glycolic acid and oxalic acid. Oxalate, the conjugate base of oxalic acid, is an excellent ligand for metal ions. The glycolic acid is then metabolized to glyoxylic acid and finally to oxalic acid. Lichen can chemically weather minerals such as calcite by producing organic acids like oxalic acid. It is the dimethyl ester of oxalic acid. Rhubarb leaves contain poisonous substances, including oxalic acid, a nephrotoxin. Cadmium catalyzes the transformation of vitamin C into oxalic acid. Hyacinth bulbs are poisonous; they contain oxalic acid. Oxalic acid is an important reagent in lanthanide chemistry. These diesters are subsequently hydrolyzed to oxalic acid. Oxalic acid is an organic compound with the formula CHO. It also dissolves well in solutions of chelating agents such as EDTA and oxalic acid.