The author described in this paper certain anomalous appearances presented by venous blood when left in contact with coloured porcelain. When blood drawn from a vein is either allowed to coagulate in a porcelain cup, or after coagulation is left in it for some hours, the dark purple tint characteristic of venous blood is found to be altered to the bright arterial hue, wherever it was in contact with any elevated device of the green colour, which is communicated by means of protoxide of chrome. In one instance the same effect was produced by a device of a crimson tint; but in more than sixty trials with this and every other variety of colour used in ornamenting porcelain, the author could observe no such effect as was invariably produced by patterns of a green tint.