The ornamental design for a side panel of an ink bottle, as shown and described.
FIG. 1 is a left side elevation view of my new side panel for an ink
bottle;
FIG. 2 is a front elevation view thereof; and,
FIG. 3 is right side elevation view thereof.
The top of the bottom section of an ink bottle forms no part of the claimed
design. The broken line showing of the remainder of the bottle is for
illustrative purposes only and forms no part of the claimed design.