Making a Trip Attack: Make an unarmed melee touch attack against your target. This provokes an attack of opportunity from your target as normal for unarmed attacks.
If your attack succeeds, make a Strength check opposed by the defender’s Dexterity or Strength check (whichever ability score has the higher modifier). A combatant gets a +4 bonus for every size category he is larger than Medium or a –4 penalty for every size category he is smaller than Medium. The defender gets a +4 bonus on his check if he has more than two legs or is otherwise more stable than a normal humanoid (such as a dwarf ). If you win, you trip the defender. If you lose, the defender may immediately
react and make a Strength check opposed by your Dexterity or Strength check to try to trip you. Avoiding Attacks of Opportunity: If you have the Improved Trip
My question has to deal with weapons with the statement. I am copying directly from PHB 3.5
Chain, Spiked: A spiked chain has reach, so you can strike opponents 10 feet away with it. In addition, unlike most other weapons with reach, it can be used against an adjacent foe. Because the chain can wrap around an enemy’s leg or other limb, you can make trip attacks with it.
Do weapons with this description provide a free trip attempt after a successful attack (Dealing Damage), or is one just using the weapon instead of the unarmed attack hitting the touch AC, dealing no damage? If the above answer is yes, a free trip attempt after dealing damage, then; if one has the Improved Trip Feat, do they still get the free attack after a successful trip?