Yellowish discoloration of the mucus membrane and teeth is produced by

Nitric acid- signs and symptoms They are similar to that of sulphuric acid. The abdominal pain and belching may be more. There may be severe cough, dysnoea, and breathlessness due to inhalation of fumes and irritation of air passages. There will be corrosion and yellow discoloration of the mucus membrane and teeth. Ref: FORENSIC MEDICINE AND TOXICOLOGY Dr PC IGNATIUS THIRD EDITION PAGE 409