The actual tanning of sole butts lasts three to four months, and just prior to the war the tannage consisted often of about one-third myrabs, one-third valonia, and one-third extract. The myrabs and valonia were leached together, and the extract added to the best leach to make layer liquors of the required strength. Some mimosa bark was generally used also, and now it is extensively employed to replace the valonia. The most widely preferred extract is chestnut, but quebracho, myrabs extract and mixtures have also a prominent place, and mimosa bark extract an increasing importance. It is recognized that this tannage is if anything too mellow, and that if only a smooth grain and plump butt can be ensured in the first weeks of tanning, it is much better for sole leather to employ the most astringent tans possible and the sharpest liquors (_i.e._ liquors with a small relative proportion of soluble non-tannin matters). Hence there is the tendency in sole-leather tanning to employ fresh clear liquors for the butts and use up the more mellow liquors on the "offal" (shoulders and bellies). Four types of sole butt tannage will now be described, all of which illustrate the methods employed in a modern mixed tannage. =1.= The first type consists in a four-months tannage, in which the liquors are worked down the yard. The butts pass first through the suspenders (20°-40° Bkr.) in about a week, and are rocked in the first liquors. They next enter the handlers (40°-55°) rounds of eight pits, six floaters and two dusters. Myrabs, or a mixture with algarobilla is used as dusting material. The goods remain in this set for two weeks, and should then be struck through. The suspender handlers (55°-65°) are next entered, in which they remain up to three weeks in suspension, being shifted forward on alternate days. The goods now enter the layers, of which four are given: first 70° for one week; second 75° for two weeks; third 80° for three weeks; and fourth 90° for a month. The goods thus take sixteen weeks to tan, of which ten weeks (62-1/2 per cent.) are in layers.