- Why not put wet tar on all the roads, then chase the black soles of his feet?
- Because he's not a fool.

6 seconds sound clip from the The Invisible Man (1933) movie soundboard.

You can hear this line at 00:57:06.849 in the Blu-ray version of the movie.

Quote context

[...]

- Can you tell us what plans you've got for capturing him?

- A hundred thousand men are searching and watching.

- Yes, I know. But have you any secret means of getting him?

- The police have offered 2000 pounds for the first effective means.

- Why not bloodhounds?

- The bloodhounds have lost the scent.

- Why not put wet tar on all the roads, then chase the black soles of his feet?

- Because he's not a fool.

- Now, we've got one hope, gentlemen, but I daren't say a word of it here. He may be standing there beside you, listening.

- Try and sleep now, my dear. There's nothing you can do.

- We must just pray that the police can take him without harming him.

- Stand back, close against the wall.

[...]