It is painful but thorough; it is spread on lint and renewed daily. The action is usually sufficient in three days, and the parts are then poulticed until the slough comes away, after which a simple dressing is employed. Its application is advisable for a small area only--not more than four square inches--as absorption is possible. _Galvano-cautery._--The diseased tissue is destroyed by numerous punctures with a red-heated point or by linear incision with a red-heated knife. It is often a practicable and satisfactory method. The Paquelin cautery and liquid air and carbon dioxide also have their advocates. #Describe the operative measures employed in the removal of lupus tissue.# _Linear Scarification._--The parts are thoroughly cross-tracked, cutting through the diseased tissue, and subsequently a simple salicylated ointment applied. The operation is repeated from time to time, and as a result the new growth undergoes retrogressive changes, and cicatrization takes place. _Punctate Scarification._--By means of a simple or multiple-pointed instrument numerous closely-set punctures are made, and repeated from time to time, usually with the same action and result as from linear scarification. _Erasion._--The parts are thoroughly scraped with a curette, and a supplementary caustic application made, either with caustic potash or several days' use of the pyrogallic-acid ointment. The result is usually satisfactory. The dental-burr is also useful in breaking up discrete tubercles. _Excision._--This is an effective method if the disease consists of a small pea- or bean-sized circumscribed patch. Of these various operative methods those now most favored are erasion and excision, punctate and linear scarification methods are now rarely employed. #Tuberculosis Cutis.#[D] (_Synonym:_ Scrofuloderma.) [Footnote D: The most important clinical variety of this class is lupus vulgaris, which is considered above, separately, at some length.] #What do you understand by tuberculosis cutis?# The term is applied to those peculiar suppurative and ulcerative conditions of the skin due to the tubercle bacilli. #How does the common type of tuberculosis cutis begin?# The most common type of tuberculous ulceration or involvement of the skin usually results by extension from an underlying caseating and suppurating lymphatic gland; or it may have its origin as subcutaneous tubercles independently of these structures. It tends to spread, and may involve an area of one or several inches. [Illustration: Fig. 48. Tuberculosis Verrucosa Cutis (Negro).] #What are the clinical appearances and behavior of this type of tuberculous ulceration?#