PASSTIME

QUIZ
A.K.Raman
A person brought nine metal balls, identical in dimensions and weight. But one of them is slightly different in weight. Nobody knows whether the weight of the odd ball is more than the others or less. The problem is to identify and separate the odd ball. For doing this only a double pan beam balance is available. Weighing stones are not available. Even the double pan beam balance can be used thrice only. Is it possible to pick the odd one out? If the answer is yes, then please explain.
The problem may appear easy. Actually it is not so. Please don’t rush to see the answer. The key is to find out whether the oddball is lighter or heavier. Tease your brain. If you are successful, then alone you can enjoy the sweet feeling you experience after cracking a hard problem. Best of luck.

If you are successful, do post that you made it :) (don't post the answer for the benefit of others )or post your email address and I will email the answer.