Iron (II) chloride and iron (III) chloride are distinguished from each other using a chemical called?

Iron (II) chloride and iron (III) chloride are distinguished from each other using a chemical called $\mathit{NaOH}$.
The chemical compound iron(II) chloride, sometimes known as ferrous chloride, has the formula $\mathit{FeC}{l}_2$. The inorganic chemical with the formula $\mathit{FeC}{l}_3$ is iron(III) chloride.

It is a common iron compound in the +3 oxidation state, often known as ferric chloride. In iron (II) chloride, $\mathit{NaOH}$ will react to form dirty green precipitate but with iron (III) chloride $\mathit{NaOH}$ form a gelatinous brown ppt. Due to the difference in precipitate formed, distinguishing is possible.