Additive vessel

FIG. 1 is a front perspective view of an additive vessel showing the new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right view thereof;

FIG. 6 is a left view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof.

The broken-line showing of various elements of the additive vessel in FIGS. 1 - 8 is for environmental purposes only and forms no part of the claimed design.