The resin obtained from Brazilian jalap has been examined chemically for hydroxy acids, sugars and volatile acids. The ether insoluble portion is shown to yield on hydrolysis, two hydroxy acids, one of which is a dihydroxypalmitic acid, m.pt. 84° C, and probably 3:12 dihydroxypalmitic acid. The other is probably a trihydroxymyristic acid, m.pt. 151. 5° C. The sugars are glucose and rhamnose and the volatile acids tiglic, acetic, trimethylacetic and n–valeric. The two hydroxy acids have been named operculinolic acid and braziliolic acid respectively; the 3:12 dihydroxypalmitic acid having previously been named convolvulinolic acid in error. Die Hydrolyse der in Äther unlöslichen Fraktion des brasilianischen Jalapenharzes führt neben Glucose, Rhamnose, Tiglin–, Essig–, Trimethylessig– und n–Valeriansäure zu zwei Oxysäuren, bei denen es sich wahrscheinlich um die 3.12–Dioxypaimitinsäure und um eine Trioxymyristinsäure handelt. Die beiden Oxysäuren werden als Operculinolsäure und Brasiliolsäure bezeichnet.