![Watch Glass, 125 mm Diameter](/_next/image?url=https%3A%2F%2Fmediscawebsite01.s3.ca-central-1.amazonaws.com%2Fproduction%2Fimages%2F9640-watch-glass.jpg&w=3840&q=90)
Watch Glass, 125 mm Diameter
A watch glass is a circular, slightly convex-concave piece of glass used in chemistry as a surface to evaporate a liquid, to hold solids while being weighed, or as a cover for a beaker. The latter use is generally applied to prevent dust or other particles entering the beaker; the watch glass does not completely seal the beaker, and so gas exchanges still occur.