There are two different types of 701 carts - the one you mention with the empty chamber and the small area with a sponge and there is a version with a full sponge that takes up the entire area of the cart. What you have is the starter cart, the trial size, that comes with the printer. Just go buy a full sized one and start using that one and then getting it refilled.
You can refill the starter cart, but it is a very, very low capacity cartridge.
You can refill the starter cart, but it is a very, very low capacity cartridge.
