Chapter I: Preface

In the general advance of technical knowledge and research during the last decade, the Soap Industry has not remained stationary. While there has not perhaps been anything of a very revolutionary character, steady progress has still been made in practically all branches, and the aim of the present work is to describe the manufacture of Household and Toilet Soaps as carried out to-day in an up-to-date and well-equipped factory.

In the more scientific portions of the book, an acquaintance with the principles of elementary chemistry is assumed, and in this we feel justified, as in these days of strenuous competition, no soap-maker can hope to compete successfully with his rivals unless he has a sound theoretical as well as practical knowledge of the nature of the raw materials he uses, and the reactions taking place in the pan, or at other stages of the manufacture. We also venture to hope that the work may prove useful to Works' Chemists and other Analysts consulted in connection with this Industry.

At the same time, in the greater part of the book no chemical knowledge is necessary, the subject being treated in such a way that it is hoped those who are not directly engaged in the manufacture of soap, but who desire a general idea of the subject, will find it of value.

In the sections dealing with the composition and analysis of materials, temperatures are expressed in degrees Centigrade, these being now almost invariably used in scientific work. In the rest of the book, however, they are given in degrees Fahrenheit (the degrees Centigrade being also added in brackets), as in the majority of factories these are still used.

As regards strengths of solution, in some factories the use of Baumé degrees is preferred, whilst in others Twaddell degrees are the custom, and we have therefore given the two figures in all cases.

In the chapter dealing with Oils and Fats, their Saponification Equivalents are given in preference to Saponification Values, as it has been our practice for some years to express our results in this way, as suggested by Allen in _Commercial Organic Analysis_, and all our records, from which most of the figures for the chief oils and fats are taken, are so stated.

For the illustrations, the authors are indebted to Messrs. E. Forshaw & Son, Ltd., H. D. Morgan, and W. J. Fraser & Co., Ltd.

W. H. S. H. A. A.

LONDON, _September_, 1908.

CONTENTS

PAGE

CHAPTER I.

INTRODUCTION. 1

Definition of Soap--Properties--Hydrolysis--Detergent Action.

CHAPTER II.

CONSTITUTION OF OILS AND FATS, AND THEIR SAPONIFICATION 6

Researches of Chevreul and Berthelot--Mixed Glycerides--Modern Theories of Saponification--Hydrolysis accelerated by (1) HEAT OR ELECTRICITY, (2) FERMENTS, Castor-seed Ferment, Steapsin, Emulsin, and (3) CHEMICAL REAGENTS, Sulphuric Acid, Twitchell's Reagent, Hydrochloric Acid, Lime, Magnesia, Zinc Oxide, Soda and Potash.

CHAPTER III.

RAW MATERIALS USED IN SOAP-MAKING 24

Fats and Oils--Waste Fats--Fatty Acids--Less-known Oils and Fats of Limited Use--Various New Fats and Oils Suggested for Soap-making--Rosin--Alkali (Caustic and Carbonated)--Water--Salt--Soap-stock.

CHAPTER IV.

BLEACHING AND TREATMENT OF RAW MATERIALS INTENDED FOR
SOAP-MAKING 41

Palm Oil--Cotton-seed Oil--Cotton-seed "Foots"--Vegetable Oils--Animal Fats--Bone Fat--Rosin.

CHAPTER V.

SOAP-MAKING 45

Classification of Soaps--Direct combination of Fatty Acids with Alkali--Cold Process Soaps--Saponification under Increased or Diminished Pressure--Soft Soap--Marine Soap--Hydrated Soaps, Smooth and Marbled--Pasting or Saponification--Graining Out--Boiling on Strength--Fitting--Curd Soaps--Curd Mottled--Blue and Grey Mottled Soaps--Milling Base--Yellow Household Soaps--Resting of Pans and Settling of Soap--Utilisation of Nigres--Transparent soaps--Saponifying Mineral Oil--Electrical Production of Soap.

CHAPTER VI.

TREATMENT OF SETTLED SOAP 60

Cleansing--Crutching--Liquoring of Soaps--Filling--Neutralising, Colouring and Perfuming--Disinfectant Soaps--Framing--Slabbing--Barring--Open and Close Piling--Drying--Stamping--Cooling.

CHAPTER VII.

TOILET, TEXTILE AND MISCELLANEOUS SOAPS 77

Toilet Soaps--Cold Process soaps--Settled Boiled Soaps--Remelted Soaps--Milled Soaps--Drying--Milling and Incorporating Colour, Perfume, or Medicament--Perfume--Colouring matter--Neutralising and Superfatting Material--Compressing--Cutting--Stamping--Medicated Soaps--Ether Soap--Floating Soaps--Shaving Soaps--Textile Soaps--Soaps for Woollen, Cotton and Silk Industries--Patent Textile Soaps--Miscellaneous Soaps.

CHAPTER VIII.

SOAP PERFUMES 95

Essential Oils--Source and Preparation--Properties--Artificial and Synthetic Perfumes.

CHAPTER IX.

GLYCERINE MANUFACTURE AND PURIFICATION 111

Treatment of Lyes--Evaporation to Crude Glycerine--Distillation--Distilled and Dynamite Glycerine--Chemically Pure Glycerine--Animal Charcoal for Decolorisation--Glycerine obtained by other methods of Saponification--Yield of Glycerine from Fats and Oils.

CHAPTER X.

ANALYSIS OF RAW MATERIALS, SOAP, AND GLYCERINE 117

Fats and Oils--Alkalies and Alkali Salts--Essential Oils--Soap--Lyes--Crude Glycerine.

CHAPTER XI.

STATISTICS OF THE SOAP INDUSTRY 140

APPENDIX A.

COMPARISON OF DEGREES, TWADDELL AND BAUMÉ, WITH ACTUAL DENSITIES 147

APPENDIX B.

COMPARISON OF DIFFERENT THERMOMETRIC SCALES 148

APPENDIX C.

TABLE OF THE SPECIFIC GRAVITIES OF SOLUTIONS OF CAUSTIC SODA 149

APPENDIX D.

TABLE OF STRENGTH OF CAUSTIC POTASH SOLUTIONS AT 60° F. 151

INDEX 153