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 and potassium hydrates — Payne and Pullman’s process — Alkaline carbonates — Alkaline sulphides — Sodium sulphide — Calcium Sulphydrate — Gas-lime — Tank-waste — Lufkin’s liming preparation — Barium sulphydrate — Realgar, or red sulphide of arsenic — “Inoffensive” unhairing solution — Earp’s patent — Unhairing on the beam — Unhairing machines — Vaughn machine — Leidgen machine — Unhairing in stocks and wash-wheel — Jones machine — Fleshing — Vaughn fleshing machine — Rounding PAGE [119]
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]