I Could Be There for You Lyrics

Lyric discussion by signed_up_for_cake 

Cover art for I Could Be There for You lyrics by Eisley

[ the first line ]

I think she's talking about sulfur simply as a gas, which it is under normal temperatures and pressure conditions.

A gas, by nature, is not confined to a certain state or place. It expands forever unless contained.

And it makes sense that she would follow it with "in the night".

In summation,

I read it as...

I'm solid during the day, but when my friends call at night, I disappear.

I'm terrible with lyric analysis and I'm trying to get better, so come on and correct me.