When a capillary tube is partly dipped inside a liquid vertically, then there will be ascent or descent of the liquid inside the capillary tube.

1. In case of a liquid which wets the glass plate, as in case of water, alcohol, etc, when the glass plate is dipped vertically inside that liquid then the level of the liquid along the side of the plate rises up a little. So when a glass capillary tube is dipped inside this kind of liquid then at the point of contact the meniscus is concave upwards as shown in the Fig.1.
2. In case of a liqiod which does not wet the glass plate, as in case of mercury, when the plate is dipped vertically inside that liquid then the of the liquid along the side of the plate is depressed a little. So when a glass capillary tube is dipped inside this kind of liquid at the point of contact the meniscus is concave downward or convex upwards as shown in the Fig.2.

So the shape of liquid meniscus in a capillary tube may be convex or concave depending on the nature of the liquid.