The doctor then slowly poured some drops of the lemonade from the decanter into the cup, and in an instant a light cloudy sediment began to form at the bottom of the cup; this sediment first took a blue shade, then from the color of sapphire it passed to that of opal, and from opal to emerald. Arrived at this last hue, it changed no more. The result of the experiment left no doubt whatever on the mind.