how to help two cats be at peace with each other

Question
My orange tabby is 5 years old. I adopted her from the humane society about 8 months ago. She is quite shy, does not liked to be pet on her body (only her head), very tamed and will come when I call her. She is quite a neat cat but very particular about her food, and is playful at night time.
Over a month ago, I brought home a grey calico tabby from the humane society. She is 1 year old. I live in a bachelor so there was no way I would lock my new cat in there all day. The cats live in the open space and still hiss at each other, taking out the claws daily but neither have been physically hurt, cut or bruised. They dont really make physical contact when they "fight". Both the cats are fixed. I am hoping that they wll become best friends, but its been over a month and they are still taking the claws out on each other. The old cat uses the little box and never makes any accident. The new cat constantly (almost daily) pee outside the box. I am tired of cleaning after her. I have separate food bowls for them in different locations so they do not bicker over food. I am thinking of putting a second litter box as when I first had the new cat I used two little box and accidents never happened with the new cat.
I am getting stressed out that they are not getting along. I have read alot of articles on how to introduce the second cat, but they keep on taking the claws out against each other (no physical contact) and it frustrates me that they are not best friends even after over a month.
I live by myself, work full time and doing grad school. I am not home much and do not play with my cats. I will rub them and let them sleep in my bed, and occassionally play with them and their toys. I dont spend much time at home so I would like the first cat to find a companion in the second cat.
Please help us!

Answer
Huong,

It may be best for the cats and for you if you re-home the cats until you finish grad school and CAN be home more. It's not fair to the cats. Cats need time and attention, they are a responsibility. If the cats are unhappy about being locked up together all the time and no human interaction the situation probably will not improve. The younger cat peeing outside the box is an indication that the cat is stressed.

You might consider a cat door so they can go outside too.

With a bachelor there is also no where for the cats to go to get time out from each other or to have their own territory. There is not any magic trick to get them to get along, especially if you are not there enough to referee.

Tabbi