| Answer | Crossword Clue |
|---|---|
| PORN | Blue matter |
| SMUT | Blue matter |
| LITMUS | Blue coloring matter |
| indigotin | the blue colouring matter of indigo, obtained by hydrolysis from indican |
| indigotins | INDIGOTIN, the blue colouring matter of indigo, obtained by hydrolysis from indican |
| litmus | blue coloring matter obtained from certain lichens, esp. Roccella tinctoria. In alkaline solution litmus turns blue, in acid solution, red: widely used as a chemical indicator |
