Kennedy repeated the process in reverse, using a blue powder to make the ink visible again.

But I cannot stop work on the blue powder.

He went to his office early and through a microscope found particles of blue powder on the radio loudspeaker.

A lead scientist for a pharmaceutical company is killed by a blue powder that turns his bones into dust.

Others give off a kind of blue powder.

One was filled with pale blue powder, the other a sealed disc.

The powder blue one would have to do.

David drew out a packet of the blue powder.

Cunningham lay there for a moment breathing in the cloud of swirling blue powder.

The plate was smoking and what should have been blue powder was now a black crust.