I think i have seen a ghost heres my story;

I was about 11 years old over at my best friends house..we had planned to play D&D all night but we could not find the dice. So instead we played tag around the house the ussual knocking things over routine..then just as i was chasing my buddy he ran passed a lamp(one of those ones that stand on it own) and must of hit it when it fell over and there went the light..so after some cleaning up we sat down..and were trying to figure out what to say to his mom when she got back..and all of a sudden..he noticed a whitish light at the top of room and it sortove turned into a smoke(more of a thin white fog) and floated downward and hoverd in the hall way before it proceded to float down the hallway and dissapear. he later said he thought a woman in the figure..but i didnt really think i saw anything.

I wonder do normal like 40 watt light produce any gases that could have cause such an illusion?