The Liebermann reagent named after Hungarian chemist Leo Liebermann (1852-1926) is used as a simple spot-test to presumptively identify alkaloids as well as other compounds.
It is composed of a mixture of potassium nitrite and concentrated sulfuric acid.
[1][2] 1 g of potassium nitrite is used for every 10 mL of sulfuric acid.
[4][5] It is used to test for cocaine, morphine, PMA and PMMA.
The test is performed by scraping off a small amount of the substance and adding a drop of the reagent (which is initially clear and colorless).