In this species the standard is longer than the other petals. The flowers are white, numerous, the racemes more loose and longer than in the first species. The petals are unequal, the banner longer than wings or keel, and the calyx shorter than the corolla by more than one-half. As much as 0.2 per cent has been obtained by distilling the fresh herb with water. Coumarin is soluble in ether, volatile and fatty oils, in acetic and tartaric acids, also soluble in boiling alcohol, and requires 400 parts of cold, and 45 parts of hot water for solution.
Hot alkalies convert it into ortho-coumaric acid.
Action, Medical Uses, and Dosage. The medicinal properties of melilotus are undoubtedly chiefly due to coumarin. Many observers have found it peculiarly effective in certain painful disorders , particularly neuralgias of long standing and associated with debility. It is adapted to idiopathic neuralgic headaches, and to neuralgic affections not depending upon reflex causes, although it has given good results in headaches arising from painful disorders of the stomach. Recurring neuralgia, especially from cold or fatigue, have been promptly relieved by small doses of the drug.