Soap and Detergent
Soap is a cleansing agent which, when dissolved in water, removes dirt from soiled surfaces. Made from animal fat and wood ashes, soap is one of the earliest chemical inventions and was first used as a salve or ointment. Many ancient cultures made and used soap, the Sumerians as early as 3000 B.C. The ancient Egyptians used a soap-like paste to treat skin disease.
The Romans learned about soap from conquered peoples, perhaps the Celts or the Gauls. In his Historia naturalis the Roman naturalist Pliny the Elder (ca. 23 A.D.-79 A.D.) mentions soap used by the Gauls as a hair dye and salve. The Greco-Roman physician Galen (ca.130-c.200) wrote about soap as a medication and--for the first time--as a cleanser in one of his treatises published in the second century A.D. The Arab alchemist Jabir ibn Hayyan (Geber) also mentioned soap as a cleanser in the eighth century.
By then, it was known throughout southern Europe. Marseilles, France, and Genoa and Venice, Italy, became the leading manufacturers of the substance because of their abundant supplies of olive oil and crude soda. Soapmaking in England began around 1200 in Bristol. Refinements to the soapmaking process in the sixteenth century produced a purer soap. Since English authorities considered soap a luxury, it was heavily taxed until 1853, and soap-boiling pans were locked each night by local tax collectors.
Soapmakers plied their trade in America at Jamestown, Virginia, beginning in the early 1600s. Although manufactured soap was available in America by 1800, rural Americans continued to make their own soap at home from wood ashes and animal fat, just as the Sumerians and Phoenicians had, into the early 1900s.
The modern soapmaking industry was launched in 1791 when French chemist Nicolas Leblanc (1742-1806) developed a method of obtaining sodium carbonate from common salt rather than from plant ashes. Methods were also developed to recover glycerin during soapmaking, which could then be reused in place of purchased vegetable oils. These improvements made soapmaking easier and cheaper, which in turn made soap widely available at affordable prices.
In 1823 another French chemist, Michel-Eugènem Chevreul (1786-1889), uncovered the chemical constitution of fats in soap, putting soapmaking on a sound scientific basis. Ingredients were gradually refined so that soap cleaned more effectively and also became mild, fragrant, and attractively colored.
Making soap at home was a major—and tedious—domestic chore. Even after manufactured soap became available, it was sold only in bar form, and shaving or slicing it constituted yet another household chore. Lever Brothers alleviated this problem in 1906 with its introduction of Lux Flakes. A proliferation of soap chips, flakes, powders, and beads followed rapidly, prompting such intense advertising competition among soap manufacturers that the radio serials on washday Mondays became known as "soap operas."
Unfortunately, soap as a home laundering agent had a serious disadvantage: it reacted with substances in hard water to produce an insoluble scum--the ring around the bathtub and the dull grayness on freshly washed clothes. In 1916 a German scientist, Fritz Gunther (1877-1957), developed a synthetic surfactant that kept oil and grease suspended in water so that it was rinsed away rather than deposited as soap scum. In l933 Proctor & Gamble (P & G) introduced Dreft, the first synthetic detergent using surfactants for household use. P&G's Tide, which debuted in 1947, was the first effective synthetic detergent and ushered in the detergent era. By 1955, detergents were outselling soaps. Much soap is sold in bar form today for personal bathing, although liquid soap dispensers for bathroom and kitchen use are increasing in popularity.
Until about 1940, soap was made in huge kettles; most soap today is made by a continuous process using stainless steel tubes called hydrolizers. After the soap is produced, it is pumped into giant mixers called crutchers, where other ingredients such as perfumes, colors, and builders--substances that help loosen dirt--are added. The soap is then hardened into bars, rolled into flakes, or spray-dried into powder.
Initially, synthetic detergents posed an environmental threat because their surfactants did not break down under bacterial action in the soil or during sewage treatment. The use of biodegradable surfactants in detergent formulas has helped relieve that hazard, although concern continues over the use of phosphates in detergents. Any of a range of compounds from phosphoric acid and a natural plant nutrient as well, phosphates appear in detergent formulas as a brightening agent. Unfortunately, their natural fertilizing capabilities can alter the ecological balance of lakes and streams by stimulating algae and aquatic plant overgrowth, or eutrophication. The subsequent decay of that overgrowth robs the water of oxygen and in severe instances leads to massive fish kills. The trend today is toward elimination of these compounds.
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