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668 stages of the disease, considering that relapses are more prone to occur after their too early employment. Mercury, owing to its proneness to cause anæmia, is less frequently employed than potassium iodide. Where the eruption is persistently squamous, or papular, arsenic is frequently prescribed. Some touch the yaws with sulphate of copper; some apply nitrate-of-mercury ointment; others, iodoform ointment; others leave them alone, confining their local measures to the enforcement of cleanliness. When the soles of the feet are attacked, the feet ought to be soaked in warm water to soften the epidermis, which should then be cut away sufficiently to liberate the subjacent yaw. Ulceration must be treated on ordinary principles. During convalescence iron, arsenic, and quinine are indicated. Except where much bone destruction has taken place, salvarsan and, better, neo-salvarsan have a rapid and remarkable curative effect in yaws in every stage of the disease, including "gangosa." They are now the recognized specific treatment, and may be given intravenously or intramuscularly. The dose is 4 to 8 gr. for an adult male, proportionately less for females and children. The reader is referred to p. 243 for a description of the technique of administration. Alston has made the curious and interesting observation that the serum obtained from a blister applied to a yaws patient who has recently been treated with salvarsan acts, when injected subcutaneously into another yaws patient, as effectually as a dose of salvarsan. The systematic use of salvarsan in a yaws community would, if thoroughly carried out, promptly get rid of the endemic, and, wherever possible, should be enforced.