Batter hits sharp ground ball to first baseman who has trouble fielding the ball. Ultimately, the first baseman holds the ball in his bare hand and tags first base with his empty glove before the batter touches first base. Is the batter out?

Answer: Yes, the batter is out. A fielder can put out a runner by tagging a base with an empty glove. Tagging the base with the glove on your hand is not much different from tagging the base with the shoe on your foot. However, a fielder cannot put out a runner by tagging the runner with an empty glove, which again, is consistent with the inability to tag the runner with a foot/shoe.

Under Official Baseball Rules 2.00 A TAG is the action of a fielder in touching a base with his body while holding the ball securely and firmly in his hand or glove; or touching a runner with the ball, or with his hand or glove holding the ball, while holding the ball securely and firmly in his hand or glove. It is not a tag, however, if simultaneously or immediately following his touching a base or touching a runner, the fielder drops the ball. In establishing the validity of the tag, the fielder shall hold the ball long enough to prove that he has complete control of the ball. If the fielder has made a tag and drops the ball while in the act of making a throw following the tag, the tag shall be adjudged to have been made.

Also, The PERSON of a player or an umpire is any part of his body, his clothing or his equipment.