No. 2.

My first is in pen, but not in ink.

My second is in iron, but not in link.

My third is in wonder, but not in surprise.

My fourth is in danger, and also in disguise.

My fifth is in engine, and also in steam.

My sixth is in rafter, but is not in beam.

My whole is a something destructive and black,

And when it's in motion you'd better keep back.

Percy F. Jameson.