What is "tap cinder"

Tap \Tap\, n. [AS. t[ae]ppa, akin to D. tap, G. zapfen, OHG. zapfo, Dan. tap, Sw. tapp, Icel. tappi. Cf. Tampion, Tip.]

1. A hole or pipe through which liquor is drawn.

2. A plug or spile for stopping a hole pierced in a cask, or the like; a faucet.

3. Liquor drawn through a tap; hence, a certain kind or quality of liquor; as, a liquor of the same tap. [Colloq.]

4. A place where liquor is drawn for drinking; a taproom; a bar. [Colloq.]

5. (Mech.) A tool for forming an internal screw, as in a nut, consisting of a hardened steel male screw grooved longitudinally so as to have cutting edges. On tap.

   1. Ready to be drawn; as, ale on tap.

   2. Broached, or furnished with a tap; as, a barrel on tap.

      Plug tap (Mech.), a screw-cutting tap with a slightly tapering end.

      Tap bolt, a bolt with a head on one end and a thread on the other end, to be screwed into some fixed part, instead of passing through the part and receiving a nut. See Illust. under Bolt.

      Tap cinder (Metal.), the slag of a puddling furnace.

n. The slag from a puddling furnace.