CHAPTER XIV.
ALUM TANNAGE, OR TAWING.
Nature of leather — Mineral tanning substances — Salts of aluminium — Alums — Aluminium sulphate — Effect of salt in tawing — Basic alumina solutions — Tawing of skins for rugs — Calf-kid manufacture — Glove-kid — Green leather and other combination tannages PAGE [184]
CHAPTER XV.
IRON AND CHROME TANNAGES.
Iron tannages — Chrome tannages — Chemistry of chromium compounds — Knapp’s method of chrome tannage — Cavallin — Swan — Heinzerling — Hummel’s improvement — Schultz’s method — Theory of the two-bath process — Practical management of the two-bath process — Dennis’s chrome tanning liquor — Procter’s liquors — Theory of basic process — Practical use of basic liquors — Washing and neutralisation — Effect of sulphur on chrome leather — Bluebacking — Fat-liquoring — Dyeing of chrome leather — Glazing and finishing PAGE [198]
CHAPTER XVI.
PRINCIPLES OF THE VEGETABLE TANNING PROCESSES.
Methods of sole-leather tanning — Finishing of sole-leather — Theory of vegetable tannage — Deliming of sole-leather — “Mellowness” of liquors — Penetration of tannage — Drying of sole-leather — Tanning of dressing leathers — Preparation for tannage — Avoidance of “bloom” — Tannage of moroccos and other skins PAGE [220]
CHAPTER XVII.