"Soap is... the first manufactured substance with which we come into contact in our lives...”
John A. Hunt, A Short History of Soap
Soap, in the form we know it today, was first produced by the Babylonians in around 2800 B.C.E. Clay cylinders containing a soaplike material were found during excavations of Babylon. Engraved in the side of a cylinder was a recipe for boiling fats with ashes.
Soap works by acting as an emulsifying agent. Each soap molecule consists of a long, fatty tail and an electrically charged "head." In water the soap molecules form small spheres, called micelles, where the charged heads are on the outside and the water- repelling fatty chains are in the middle. As dirt and grease are not soluble in water, they are contained within the micelles. The micelles can then be washed away, leaving behind a clean surface.
True soap was made by boiling oil and fat with alkaline salts to form glycerin and the salts of fatty acids. The salts are solid and are like the soap we use today. Sodium salts make hard soaps, while potassium salts produce a softer product. Calcium and magnesium salts form an insoluble residue, the scum that soap produces in hard water.
The first hard white soap was produced in Spain from olive oil and the ashes of the salsola plant. However, it was only in the late nineteenth century, after processes for producing alkalis had been discovered, that there was a rapid expansion in the commercial production of soap.
