(rare,chemistry) A poorly characterized cyclic cyanide; [(CN)2NH]3, C6N4 or similar.
1857,William Allen Miller,Elements of Chemistry: Part III, Organic Chemistry, page 603:
Mellon (C18N13; Liebig).— This anomalous compound was originally supposed by Liebig to contain C6N4, but he has recently repeated and varied his experiments upon it, and has altered its formula as above.
1916,Victor von Richter,Organic chemistry, volume I, Chemistry of the Aliphatic Series, page 473:
It sublimes on heating and decomposes into mellon and NH3.