new kitty. how long?

we adopted a beautiful deaf cat from the humane society. We kept him in a separate room. We tryed them together for a few minutes and it didn't work out so we kept them apart. we switched rooms. switched toys. put new cat in carrier and put them together feeding them treats. put one on either side of a screen door while feeding them treats. but they still try to attack each other through the door and when we open the door to get in the room they always try to attacked. they don't even hiss or warn each other (not that the new kitty could hear it) they just lunge at each other. its been one month (i know it hasnt been long) and they are still so agressive. they have bite wounds from hurting one another and have even hurt each other threw the door! i expected to have some improvment by now or is it still to soon? my boyfriend wants to give him back to the shelter even though he loves him but im not ready to give up. should i give it more time or just accept the fact that they just wont get along?

It really depends on the cats, and these two sound like they had a rough start. Cats will always remember those first introductions. If they are full on fighting, then it is going to take a long time for them to learn to get along. I would recommend Pamela Johnson Bennett's book cat-vs-cat as well as Hiss-N-Tell before you go further with these two. Are they both fixed?

yes they are both fixed but very close to when they met.