A'~(7ticfl~,~ o j .' ~iri,i7z~jd,.oZ,.~~~)~~~.ii~~~~e." IN a former p i p e r (Trans., W93, 63, 1047) i t n a s shown that the action of dilute sulphuric acid on isoiiitrosocitrazinic acid gives rise t o a sparingly ~a l n b l e , blue substance, exhibiting metallic lustre, and that t h e compound probably has the constitu tioii CH HC~'C0