Nessler's reagent

Ness·ler's reagent

noun \ˈnes-lərz-\

Definition of NESSLER'S REAGENT

: an alkaline solution of potassium mercuric iodide used in chemical analysis especially in a test for ammonia in aqueous solution (as when obtained from water, blood, or urine) with which it forms a yellowish brown color or precipitate—called also Nessler's solution