The ornamental design for a portion of a bottle, as shown and described.
FIG. 1 is a perspective view of a bottle showing our new design;
FIG. 2 is a front elevation plan view thereof, the opposite side being identical;
FIG. 3 is a side elevation plan view thereof representing a partial rotation of the bottle about its vertical axis, the opposite side being identical;
FIG. 4 is a top view thereof; and,
FIG. 5 is a bottom view thereof.
The broken line showings immediately adjacent to the shaded areas represent unclaimed boundaries of the design and form no part of the claimed design. The remaining broken line showings of the rest of the bottle are for illustrative purposes only and form no part of the claimed design.