  CHAPTER I. INTRODUCTORY AND HISTORICAL. Primitive methods of leather manufacture — Use of leather by the ancients — Progress of leather manufacture in England — Methods of production of leather — Vegetable tannages — Combination tannages — Use of aluminium, iron and chromium — Oil- and fat-leathers — Difficulties of scientific treatment PAGE 1 CHAPTER II. INTRODUCTORY SKETCH OF LEATHER MANUFACTURE. The object of tanning — Washing and soaking — Removal of hair by liming — Unhairing by putrefaction — Unhairing and fleshing — Deliming — Bating, puering and drenching — The vegetable tanning process — Currying — Alum, chrome and chamois leathers PAGE 7 CHAPTER III. THE LIVING CELL. The structure of cells — White blood-corpuscles — The yeast-cell — Epidermis cells — The building up of plants PAGE 10 CHAPTER IV. PUTREFACTION AND FERMENTATION. The nature of ferments — Organised and unorganised ferments — Classification of organised ferments — General properties of ferments — The alcoholic fermentation — The action of enzymes or unorganised ferments — The destruction of ferments by heat and antiseptics — The products of fermentation — The fermentations of the tannery — Fermentation in bating and puering — Fermentation in the tanning liquors — Moulds and CHAPTER V. ANTISEPTICS AND DISINFECTANTS. Distinction of antiseptics and disinfectants — Lime — Sulphur dioxide — Manufacture of sulphuric acid — Bisulphites and metabisulphites — Boric acid and borates — Mercuric chloride — Mercuric iodide — Copper sulphate — Zinc salts — Arsenic — Fluorides — Phenol — Use of carbolic acid — Eudermin — Creasote — Creolin — Salicylic acid — Benzoic acid — Cresotinic acid — Anticalcium — “C.T.” bate — Naphthalene sulphonic acid — Naphthols — Hydronaphthol — Oxynaphthoic acid — Carbon disulphide — Formaldehyde — Triformol — Camphor and essential oils PAGE 21 CHAPTER VI. THE ORIGIN AND CURING OF HIDES AND SKINS. Marking of hides — Fellmongering of sheep-skins — The use of salt — Salting of packer hides — Brining — Dry-salting — Indian plaster cures — Analysis of salt-earths — Salt- and iron-stains — Drying of hides and skins — Damage by insects — The warble-fly — Damage by branding — Cockle PAGE 33 CHAPTER VII. STRUCTURE AND GROWTH OF SKIN. Similarity of Mammalian skins — Development of skin — Structure of calf-skin — The epidermis — The structure of hair — The sebaceous glands — The development of hair — The hair-sheath — The hair-muscle — The hyaline layer — The corium — Connective tissue — Fat cells — Striped muscle — Elastic fibres — The unhairing process — The sweating process PAGE 46 CHAPTER VIII. THE CHEMICAL CONSTITUENTS OF SKIN. The keratin tissues — Production of gelatine from connective tissue — Analyses of hide and gelatine — Constitution of gelatine — Analysis and Reactions of gelatine — Decomposition of gelatine — Reactions of gelatine — Chondrin — Coriin — Hide-albumin — “Acid” and “alkali” albumins — Egg-albumin — Vitellin — Casein — Keratins — Elastic fibres — Analytical methods — Kjeldahl CHAPTER IX. THE PHYSICAL CHEMISTRY OF THE HIDE-FIBRE. Causes of swelling and contraction — The essentials of the tanning process — The constitution of matter — The nature of molecules — Vapour-pressure — Surface-tension — Solution-pressures — Jellies — Crystals — Osmotic pressure — Electrolytic dissociation — Electrolysis — Reactions of ions — Absorption of water by gelatine — Dehydration by alcohol — Action of acids, alkalies and salts on gelatinous fibre — Physical explanation of swelling — Action of acids on gelatine — Action of alkalies on gelatine — Effect of salt — The pickling process PAGE 73 CHAPTER X. WATER AS USED IN THE TANNERY. Impurities of natural water — Hardness — Soap test — Temporary hardness — Clark’s softening process — Archbutt and Deeley’s softening apparatus — Other appliances — Effect of temporary hardness in tanning and dyeing — Permanent hardness — Boiler scale — Mud — Iron — Alumina — Soda — Copper, lead, etc. — Sulphuric acid — Nitrates and Nitrites — Chlorine — Carbonic acid — Silicic acid — Effect of hardness on plumping — Peaty waters PAGE 93 CHAPTER XI. SOAKING AND SOFTENING OF HIDES AND SKINS. Washing of fresh hides — Danger of putrefaction — Soaking of salted hides and skins — Soaking and softening of dry and dry-salted hides — American wash-wheel — Chemical methods — Difficulty of softening hides dried at high temperature PAGE 108 CHAPTER XII. DEPILATION. Methods of depilation — Sweating process — Liming — Sources of lime — Quicklime — Slaking of lime — Solubility of lime in water — Analysis of lime — “Available” lime — Action of lime on hide — Liming in pits — Suspension limes — Effect of warming limes — Quantity of lime required — The Buffalo method — Action of old limes — Solution of hide substance by limes — Sodium CHAPTER XIII. DELIMING, BATING, PUERING AND DRENCHING. Methods of removing lime and reducing swelling — Use of acids — Lactic, acetic and formic acids — Boral — Sodium bisulphate — Boric (boracic) acid — Borax — “Pulling down” process — Use of ammonium chloride and sulphate — Pickling solutions — Drenching with lactic acid — Metabisulphite of soda — Washing out lime, French process — Nesbitt’s process — Use of carbonic acid — Carbolic acid — Cresotinic acid — Oxynaphthoic acid — “Anticalcium” — “Acrilene bating acid” — “C.T. Bate” — Use of sulphides and polysulphides — Babool pods — Bran-drenching — Bating and puering — Causes of bating effect — Pepsin — Trypsin, or Pancreatin — Wood’s researches — Erodin — Palmer’s experiments — Other artificial bates — Relative effect of dog- and pigeon-dung bates — Analysis of dungs — “Scudding,” or “fine hairing” — Preservation and use of dung PAGE 152 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 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. COMBINATION OF VEGETABLE AND MINERAL TANNAGES. Early combination tannages — Respective effect of mineral and vegetable tannages — Use of fat-liquor — Action of mineral and vegetable tanning materials on each other — Danish and Swedish glove leathers — Green leathers — Making of fat-liquors — Chrome combinations PAGE 236 CHAPTER XVIII. VEGETABLE TANNING MATERIALS. Distribution of tannin in plants — Structure of barks — Botanical list of important tanning materials PAGE 242 CHAPTER XIX. THE CHEMISTRY OF THE TANNINS. Sources of tannins — General qualities of tannins — Chemical constitution — Catechol- and pyrogallol tannins — Catechins — Tendency of Catechol tannins to darken with light — “Physiological” and “pathological” tannins — Presence of mordant colouring matters PAGE 294 CHAPTER XX. THE SAMPLING AND ANALYSIS OF TANNING MATERIALS. The International Association of Leather Trades Chemists — The American Official Association of Agricultural Chemists — The sampling of material — Preparation of solution for analysis — Extraction of solid materials — Total soluble matter — Evaporations of solutions — The weighing of residues — The determination of non-tannins — The hide-powder filter CHAPTER XXI. THE GRINDING OF TANNING MATERIALS. Primitive methods of grinding — The bell mill or coffee mill — Disc mills — Disintegrators — Carr’s disintegrator — Carter’s disintegrator — Adjustment of disintegrators — The Williams pulveriser — Myrobalans and Valonia crushers — Sawing mills — Shaving mills — Dyewood cutting machines — Screening of ground materials — Hatching of bark — Disintegrators and fire insurance — Dust from disintegrators — Chain conveyors — Belt conveyors — Vibrating conveyors PAGE 316 CHAPTER XXII. THE EXTRACTION OF TANNING MATERIALS, AND THE MAKING OF EXTRACTS. Leaching — Early forms of leaches — The press-leach system — Handling of liquors — Distributing troughs and valves — Construction of leaches — Influence of temperature — Use of silent boiling jet — Closed extractors — Sprinkling leaches — Manufacture of extracts — Decolorisation of extracts — Soluble extracts — Concentration of extracts — Yaryan evaporator — Multiple effects — The use of extracts in the tannery — Effect of temperature on extraction and colour PAGE 328 CHAPTER XXIII. FATS, SOAPS, OILS AND WAXES. Characteristics of fats and oils — Chemical constitution — Nature and production of soaps — Insoluble soaps — Distillation of fats — Solvents of oils — Drying oils — Saturated fatty acids — Non-drying liquid fatty acids — Less-saturated liquid fatty acids — Castor oil — Tallow — Neatsfoot oil — Wool fat — Holden fat — Distilled wool grease — Distilled stearine — Olive oil — Castor oil — Turkey-red oil — Linseed oil — Boiled oils — Japan for leather — Cottonseed oil — Sesame oil — Cod oil — Shark liver oil — Whale oil — Seal oil — Menhaden oil — Fish oils — Fish tallow — DÉgras and Sod oil — Waxes — Sperm oil — Beeswax — Carnauba wax — Japan wax — Volatile or essential oils — Birch oil — Wintergreen oil — Mineral oils and CHAPTER XXIV. OIL TANNAGES, AND THE USE OF OILS AND FATS IN CURRYING. Primitive use of oil in leather manufacture — Chamoising and the production of washleather — Manufacture of Moellon, or DÉgras — Sod oil — Formaldehyde leathers — “Crown” and “Helvetia” leathers — Theory of oil leathers — Processes of currying — Theory of the stuffing process — Hand-stuffing — Drum-stuffing — Stuffing of dry leather — “Spueing” and its causes — Fat-liquoring PAGE 378 CHAPTER XXV. DYES AND DYEING. Coal-tar colours — Acid and basic colours — Theories of dyeing — Fixation of colours on leather — Mordants and mordant colours — Curriers’ inks — Glazes and finishes — “Assistants” in dyeing — Bronzing — Fading of colours — Practical methods of leather dyeing — Use of dyewoods — Iron “strikers” — Tannin blacks — Staining — Theory of colour-mixtures — Finishing dyed leathers — Testing of dyes — Injurious effects of metals in dyeing PAGE 394 CHAPTER XXVI. EVAPORATION, HEATING AND DRYING. Theory of evaporation — Boiling point and vapour-pressure — Consumption of heat in evaporation — Heat-units — Mechanical energy of heat — Evaporation by “multiple effect” — Vapour-pressure of atmospheric moisture — Wet and dry bulb thermometers — Heat and air required in leather-drying — Loss of heat by buildings — Quantity of heat given by steam and hot-water pipes — Screw-fans for drying — Centrifugal fans — “Turret” dryer — Downward ventilation — Arrangement of steam-pipes — Hot water pipes PAGE 420 CHAPTER XXVII. CONSTRUCTION AND MAINTENANCE OF TANNERIES. Selection of site — Arrangement of buildings — Fire insurance — Automatic sprinklers — Possibility of extension — Production and distribution of CHAPTER XXVIII. WASTE PRODUCTS AND THEIR DISPOSAL. Hair — Fleshings and glue-stuff — Fat — Bate-shavings — Horns — Spent tan — Tan-furnaces — Sewage and other waste liquids — Chemical purification of sewage — Settling tanks — Filter-presses — Bacterial purification of sewage — Tannery waste-liquors PAGE 460 APPENDIX A. METHOD OF THE INTERNATIONAL ASSOCIATION OF LEATHER-TRADES CHEMISTS FOR THE ANALYSIS OF TANNING MATERIALS: Corrected to 1901. Sampling from bulk — Preparation for analysis — Preparation of infusion — Determination of tanning matters and non-tannins — Colour-measurement — Analysis of used liquors PAGE 475 APPENDIX B. THE DECIMAL SYSTEM. Metrical weights and measures — Centigrade thermometer PAGE 481 APPENDIX C. METHOD OF ANALYSIS OF TANNING MATERIALS OF THE AMERICAN ASSOCIATION OF OFFICIAL AGRICULTURAL CHEMISTS: Corrected to 1901. Preparation of sample — Quantity of material — Moisture — Total solids — Soluble solids — Non-tannins — Tannins — Testing of hide-powder — Testing non-tannin filtrate PAGE 482 APPENDIX D. LISTS OF COAL-TAR DYES SUITABLE FOR DYEING AND STAINING LEATHER, furnished by Mr. M. C. LAMB. Colours for staining leather — Colours for dyeing vegetable-tanned leather — Dyeing and finishing chrome-leather — List of colours suitable for chrome-leather PAGE 485 INDEX PAGE 499 PRINCIPLES line
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