In 1844, he wrote a book in which he finally revealed the ingredients: licorice, myrrh, sassafras oil and quinine.

The former is made from sassafras oil, which is derived mostly from endangered rain forest trees in Brazil and Southeast Asia.

Safrol, an ether which is the chief constituent of sassafras oil, and also found in considerable quantity in camphor oil.

Rheumatic Liniment.—Olive oil, spirits of camphor and chloroform, of each two ounces; sassafras oil, 1 drachm.

It is sold as an artificial sassafras oil, and is very much used in perfuming cheap toilet or household soaps.