newbie needs help - hardwood floors - stuff in bettween? - pic link too

Hi there.
I live in an old old building. All hardwood floors. In between the floorboards is this stuff. Black and sometimes tan stuff. Used to fill the gaps.
Looks like this, with the "|'s" being the stuff:
beam|beam|beam|beam| etc...
Here is a photo:
http://home.neo.rr.com/bughead/floor.jpg
Well that black stuff is in need of a refilling in several areas where it has chipped out. The missing areas are causing cold air to come up from the storage area on the first floor.
What is that stuff? Caulking? I imagine I'd need to put something in there that could expand and contract when the temperature changes.
I would need the stuff to be black. I do NOT want to have to do any sanding or staining whatever I put in there. I want to do this as cheaply as possible.
Thanks a bunch,
Loomis
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Looks like roof sealant.
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Young Carpenter

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The black part is probably where it got dirty. They make fillers for wood floors and I know a couple of floor installers that make their own from the sanding dust, whiting, boiled linseed oil and a little color. However, I don't know about using the filler on already finished floors. You might call a flooring company or a wood floor installer and ask them.
Preston

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Dont know what is in there but I know what to replace it with.
Get some natural rope just big enough whereas it must be pressed in. Stain in black with regular wood stain. Very easy to stain and shouldnt cost alot.

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