Calcium Carbide is a substance that reacts with water to create acetylene gas, which is extreamly flamible. In the late 1910's Tomas Wilson discovered how to create this by accident while attempting to make Aluminum in an electrical furnace. But enough with the history:

To make Calcium Carbide you will need:

-Calcium Oxide (lime, can be found seasonaly at gardening stores) --Calcium hydroxide (slaked lime) will work for this also

-(2) Terra Cotta flower pot (orange looking clay)

-Carbon (charcoal will work)

-Arc welder w/ carbon arc electrodes

First take a flower pot and drill two holes, one on each side near the bottom, then pour some Calcium Oxide into the pot slightly below the holes. Crush the charcoal (a hammer works great and is satisfying) and place it in the lime. Put the second pot upside down on top of the other to make a container. Then with your arc welder at about 105 Amps, create an arc for about 1 min. Let it cool down for a while (DONT BE AN IDIOT AND TRY TO COOL IT FASTER WITH WATER).

Open it up and there should be grey blobs around your electrodes (and maybe some un used material). This is your Calcium Carbide and will fizz when it comes into contact with water.

calium carbide creates hydrogen when it reacts with water and limestone is calcium carbonate.

http://en.wikipedia.org/wiki/Acetylene
It is kind of each of what you said. It is two hydrogen atoms and two carbon atoms.

actually i was completely wrong. i've been lied to. ignore what i said. and wtf is lime? i thought he meant limestone but apparently there is a substance that is called lime. i feel retarded

tis fine, happens to most of us.