Overview:
This 1908 handbook, “The Handbook of Soap Manufacture,” by W.H. Simmons and H.A. Appleton, takes a comprehensive look at the soap-making process from a scientific and practical standpoint. It explores the chemical properties of fats and oils, the various methods of saponification, and the different types of soaps produced, including household, toilet, and textile soaps. The authors also discuss the importance of glycerine production and the intricacies of soap perfumes, providing insights into both natural and synthetic scents.
The handbook serves as a valuable resource for anyone interested in understanding the soap-making industry, including soap manufacturers, chemists, and analysts. It bridges the gap between theoretical knowledge and practical application, offering a detailed and informative guide to the processes involved in creating a variety of soap products.
Key Findings:
- Saponification is a complex chemical reaction involving the breakdown of fats and oils into fatty acids and glycerine, with the fatty acids subsequently combining with alkali to form soap.
- Different methods of saponification exist, including hydrolysis using heat or electricity, enzymatic reactions, and chemical reagents like sulfuric acid, Twitchell’s reagent, and caustic soda or potash.
- Rosin plays a significant role in soap-making, contributing to lathering properties and a softer texture.
- Glycerine production is an essential aspect of soap-making, and its recovery from spent lyes is a crucial element in economic efficiency.
- Soap perfumes are a complex subject, involving both natural and synthetic ingredients. The authors provide a detailed overview of common essential oils and their properties, as well as the advancements in artificial and synthetic perfumes.
Learning:
- Understanding the Chemistry of Soap: Readers will gain insight into the fundamental chemical reactions involved in soap-making, including the saponification process and the properties of fats and oils.
- Exploring Different Soap-making Techniques: The handbook details various methods of soap production, from traditional cold-process methods to more advanced techniques using enzymes or chemical catalysts.
- Appreciating the Importance of Glycerine: Readers will learn about the historical and economic significance of glycerine recovery, as well as the different grades of glycerine produced and their applications.
- Navigating the World of Soap Perfumes: The text provides a comprehensive guide to natural and synthetic perfumes used in soap-making, offering valuable information on the properties and applications of different scents.
Historical Context:
The handbook was written in 1908, a time when the soap industry was experiencing significant growth driven by scientific advancements in chemistry and the availability of new materials. The authors highlight the shift from traditional, rule-of-thumb methods to more scientific and efficient production processes.
Facts:
- Soap was first introduced to Rome from Germany, having been discovered by the Gauls.
- The first recorded soap manufacture in London was in 1524.
- Chevreul’s research on the constitution of fats revolutionized the soap industry.
- Soap is soluble in both alcohol and hot water, but less soluble in cold water due to hydrolysis.
- Sodium oleate is unusual in that it does not undergo hydrolysis except in very dilute solutions and at low temperatures.
- The addition of caustic soda or brine to a solution of soda soap causes the soap to separate out.
- The solubility of different soaps in salt solutions varies considerably.
- Hydrolysis is greater in cold and dilute soap solutions.
- The emulsifying power of soap solutions plays a crucial role in their detergent action.
- Fats and oils consist of mixtures of triglycerides, which are compounds of glycerol and fatty acids.
- The presence of stearin and palmitin, both solid at room temperature, gives firmness to fats.
- Olein, which is liquid, contributes to the softness of fats.
- The lower fatty acids are more soluble in water and distil without decomposition.
- Unsaturated fatty acids readily combine with bromine or iodine.
- The elaidin reaction involves the conversion of unsaturated fatty acids into isomeric acids with higher melting points.
- The hydrolysis of oils and fats can be accelerated by heat, enzymes, or chemical reagents.
- Castor seeds contain a ferment capable of splitting fats into fatty acids and glycerol.
- Twitchell’s reagent, a fatty aromatic sulfuric acid, facilitates the dissociation of fats.
- The use of lime for saponification dates back to 1831.
- Soda and potash are the most important saponifying agents for commercial soap production.
Statistics:
- South American mutton tallow typically has a saponification equivalent of 284.5 and an acidity of 1.11%.
- American hog’s fat typically has a saponification equivalent of 286 and an acidity of 0.53%.
- Cochin cocoa-nut oil typically has a saponification equivalent of 215.5 and an acidity of 1.52%.
- Palm-nut oil typically has a saponification equivalent of 225 and an acidity of 4.42%.
- Olive oil typically has a saponification equivalent of 288 and an acidity of 1.82%.
- Refined cotton-seed oil typically has a saponification equivalent of 290 and an acidity of 0.39%.
- Arachis oil typically has a saponification equivalent of 285 and an acidity of 0.22%.
- Maize oil typically has a saponification equivalent of 294 and an acidity of 0.4%.
- Sesame oil typically has a saponification equivalent of 295 and an acidity of 1.84%.
- Linseed oil typically has a saponification equivalent of 292 and an acidity of 2%.
- Castor oil typically has a saponification equivalent of 310 and an acidity of 1.5%.
- Pale seal oil typically has a saponification equivalent of 289 and an acidity of 0.94%.
- Whale oil typically has a saponification equivalent of 297 and an acidity of 1.49%.
- White skin grease typically has a saponification equivalent of 287 and an acidity of 4.33%.
- Pale bone fat typically has a saponification equivalent of 289 and an acidity of 8.84%.
- The saponification equivalent of rosin can vary from 312.3 to 330.5.
- The English degree for caustic soda is about 1% higher than the actual percentage of sodium oxide.
- Commercial caustic soda can range in strength from 60° to 76-77° English degrees.
- The standard for refined carbonate of potash is 90-92% potassium carbonate.
- The UK soap industry produces an estimated 7,000,000 to 8,000,000 cwt. of soap per annum.
Terms:
- Hydrolysis: The chemical breakdown of a compound by water.
- Saponification: The chemical process of converting fats and oils into soap by reacting them with alkali.
- Glyceride: A compound of glycerol and fatty acids.
- Titre: The setting point of fatty acids, a measure of their firmness.
- Unsaponifiable matter: Components of fats and oils that do not react with alkali to form soap.
- Essential oils: Aromatic oils extracted from plants, often used as perfumes.
- Synthetic perfumes: Artificial scents created in a laboratory.
- Nigre: A dark, weak soap residue that settles during soap-making.
- Milling: The process of grinding and mixing soap to achieve a smooth and homogenous texture.
- Superfatting: The addition of unsaponified fat to soap to improve its conditioning properties.
Examples:
- Cold process soap: The saponification of cocoa-nut oil with caustic soda at low temperatures, generating enough heat to complete the process.
- Soft soap: The combination of vegetable oils like linseed, olive, or cotton-seed oil with potash lye.
- Curd soap: A hard soap made from tallow, often with a small amount of cocoa-nut oil.
- Milled toilet soap: A high-quality soap base made from tallow and cocoa-nut oil, dried and milled to achieve a smooth, homogenous texture.
- Medicated soap: Soap containing specific drugs or chemicals for treating skin conditions, such as carbolic soap, coal tar soap, or sulfur soap.
- Floating soap: Soap made by incorporating air bubbles into the soap base, reducing its density so it floats in water.
- Shaving soap: A blend of soda and potash soaps, specially formulated to produce a rich, creamy lather for shaving.
- Wool scouring soap: Neutral olive-oil soft soap, ideal for removing wool fat and perspiration from raw wool.
- Cotton industry soap: Curd soap made from tallow, often with a small amount of cocoa-nut oil, used for cleaning cotton fabrics.
- Calico-printer’s soap: Neutral olive-oil soap used for cleansing printed cloth and fixing colors.
Conclusion:
“The Handbook of Soap Manufacture” offers a comprehensive overview of the soap-making industry as it existed in 1908. This insightful guide sheds light on the chemical reactions involved in saponification, the various techniques for producing different types of soaps, and the importance of glycerine production. The book also explores the intricacies of soap perfumes, highlighting the role of essential oils and the emergence of artificial and synthetic scents. By combining scientific knowledge with practical application, the authors provide a valuable resource for anyone interested in the fascinating world of soap-making.