Dragendorff test

Dra·gen·dorff test

(drā'gĕn-dōrf),
an obsolete qualitative test for bile; a drop of nitric acid added to either white filter paper or unglazed porcelain moistened with a fluid containing bile pigments produces a play of colors. The test is essentially the same as Gmelin test for bile in urine.

Dragendorff,

Georg J.N., German physician and pharmaceutical chemist, 1836-1898.
Dragendorff solution
Dragendorff test - a qualitative test for bile.