fly ball down the third base line, the ball is in foul territory, the left fielder is in fair territory reaches across the line and touches the ball and drops the ball the ball then lands foul?

Fair ball or Foul ball?

What chapter is it in the rule book? is there a website with a link to the rule?

In the case of Fair/Foul, the position of the ball when it is first touched is the only thing that matters. If the ball is over foul territory when first touched, it is a FOUL ball, if it is over fair territoory, it is a FAIR ball. The position of the fielder who first touches the ball has ABSOLUTELY NO BEARING on the fair/foul call.

There are online rule books at <a href=http://www.pony.org>www.pony.org</a> and <a href=http://www.playnsa.com/main.html>www.playnsa.com</a>. Look in the Definitions section.