Murexide also called ammonium purpurate or MX, is the ammonium

Ammonium

The ammonium cation is a positively charged polyatomic cation with the chemical formula NH. It is formed by the protonation of ammonia...

 salt

Salt

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

 of purpuric acid. It may be prepared by heating alloxantin in ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 gas

Gas

Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...

 to 100 °C, or by boiling uramil (5-aminobarbituric acid) with mercury oxide

Mercury oxide

Mercury oxide can refer to:* Mercury oxide , Hg2O* Mercury oxide , HgO...

. W.N. Hartley found considerable difficulty in obtaining specimens of murexide sufficiently pure to give concordant results when examined by means of their absorption spectra, and consequently devised a new method of preparation for murexide.