Finally the goods are placed in "layers" or "layaways," in which they remain undisturbed for a decidedly longer time. These pits contain the strongest liquors of the yard, and their principal function is to complete the tannage and give weight and firmness by the adsorption of bloom, reds, etc., in the interior of the hide. The goods are placed in horizontally, and are dusted in between with fresh tanning material which maintains the local strength of the liquor and keeps the goods somewhat apart. Drum tanning attains a more rapid penetration of the pelt by giving constant motion in stronger infusions. It is of course liable to result in an under-tannage of the interior of the fibre. After the goods have been "struck through" in the ordinary way, however, drumming in extract is increasingly used as a substitute for much labour in handling, and also to save the time spent in the early layers. REFERENCES. Procter, "Principles of Leather Manufacture," pp. 220-350. Bennett, "Manufacture of Leather," pp. 113-179. Bennett, "Celavima and Babla," L.T.R., 1914, 122. Dumesny and Noyer, "Manufacture of Tanning Extracts." _Theory_:-- Meunier and Seyewetz, Collegium, 1908, 195. Stiasny, Collegium, 1908, 117-159, 289, 294, 337. Procter and Wilson, Collegium (London), 1917, 3. Wilson, Collegium (London), 1917, 97, 100, 105. Moeller, Collegium (London), 1917, 13, 38, 46, 103; and _J.S.L.T.C._, 1917, 22, 56, 92. Bennett, _J.S.L.T.C._, 1917, 130-133, 169-182; 1918, 40; 1920, 75-86; _S.L.R._, 1916, March. SECTION IV.--FINISHING PROCESSES