The ornamental design for a chemicalstability apparatus, as shown and described.
FIG. 1 is a cross-sectional view of a chemical stability apparatus in a sealed position;
FIG. 2 is a cross-sectional view of a chemical stability apparatus in an open position;
FIG. 3 is a front view of a lower portion of the chemical stability apparatus shown in FIGS. 1 and 2;
FIG. 4 is a side view of a lower portion of the chemical stability apparatus shown in FIGS. 1 and 2;
FIG. 5 is a partial cross-sectional view of a lower portion of the chemical stability apparatus shown in FIGS. 1 and 2;
FIG. 6 is a front view of a plunger of the chemical stability apparatus shown in FIGS. 1 and 2;
FIG. 7 is a bottom view of a plunger of the chemical stability apparatus shown in FIGS. 1 and 2;
FIG. 8 is a cross-sectional view of the plunger of the chemical stability apparatus shown in FIGS. 1 and 2;
FIG. 9 is a cross-sectional view of the plunger of the chemical stability apparatus shown in FIGS. 1 and 2, taken in the direction of line 8—8 in FIG. 7; and,
FIG. 10 is a top view of a plunger of the chemical stability apparatus shown in FIGS. 1 and 2.