forms a superficial eschar, which drops off in the course of a week or so,
taking the pigment with it, and leaving a white superficial scar.
Fig. 16.—Tattoo-marks over the forearm.
over the forearm.
(3) Application of Caustic Substances.—Caustic substances applied to
the mark remove the pigment by producing an inflammatory reaction and a
superficial eschar. For instance, a mixture of papain in glycerin often
removes a tattoo-mark. Tardieu62 reports the case of a criminal who suc-
cessfully removed a tattoo-mark made of Indian ink in six days by first
macerating the skin in a paste of lard and acetic acid, then thoroughly
rubbing it with a solution of caustic potash or soda, and lastly with dilute
hydrochloric acid. Brault 63 recommends the tattooing of a solution of zinc
chloride to 40 parts of water by means of a needle into the, design. After a
few days a crust forms, which removes the pigment, when it falls off. These
caustic substances have to be used with great care as they are not only
dangerous but are often followed by disfiguring scars and keloids. Shie G1
has obtained very satisfactory results from Variot's method which consists
of tattooing into the design a 50 per cent solution of tannic acid in water
and then rubbing it vigorously with a stick of silver nitrate until the whole
surface becomes black from the formation of silver tannate in the superficial
layers of the skin. The field of the operation is then washed with cold
water. After 15 to 16 days a black, dry slough comes off spontaneously
62. Peterson, Haines and Webster, Leg. Med. and Toxic., Ed. II, Vol. I, p. 160.
63. Jour. Amer, Med. Assoc., Aug. 4, 1923, p. 409.
64. Ibid., Jan. 14, 1928, p. 94; Brit. Med, Jour., Feb. 25, 1928, p. 318,