This short film from Macro Room shows how pills dissolve in timelapse. Dissolution is a complex process driven both by flow and chemical concentration. Any small motion in the water helps erode the surface, and as the chemicals dissolve, the subsequent variations in the concentration drive additional flow. This is why we often see a turning point in how quickly the pills come apart. The initial breakdown is slow, but once enough of the pill dissolves, it enhances the surrounding flow, which increases erosion. Notice how many of the pills – liquid-filled capsules, especially – have a point where fluid begins streaming away from them. Unlike the capsules, the solid pills seem to get an extra boost from bubbles that form and then pull away material. (Image and video credit: Macro Room; submitted by clogwog)