The previous edition of Henry Oliver’s occasional column “Man Made Wonders” is here.

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If they invented soap today, it would win a Nobel prize. That’s what the economist Alex Tabarrok said during the pandemic. Soap has extraordinary antiviral, antibacterial properties. We take for granted just how easily available it is to us in modern society, one of the modern miracles to which we have become numb.

Soap has always been integral to human culture. But not as we know it. The word was once used to refer to hair dyes, such as those used by Germanic warriors to look fierce in battle. But washing has been known in human culture since ancient times. The Babalonians did it. The Egyptians did. France, Italy, Rome, and Spain did it. 

But the fall of Rome was the fall of soap. Historians bristle when you call them the Dark Ages, but there was certainly a decline in ablutions. Cleanliness, for the early Christian European world, was not always next to godliness. Hard soap was manufactured during the Islamic Golden Age and introduced to fifteenth century Europe, often scented or perfumed. James I issued a soap monopoly in Britain. But it took the industrial and scientific revolutions to provide us with the soap we know today. In the early modern period, manufacturing sites were established. Modern soap (and hygiene) might have been developed more quickly without the 1712 soap tax, causing soap to become a luxury item, restricted to the rich. The tax was only repealed in 1853.

Soap is made from fat. Early soaps were mixtures of tallow and wood-ash. At one time mutton and beef tallow was used, often imported from Australia. For a good lathering soap, the tallow had to be blended with something like coconut oil or castor oil. Hard tallows did make good shaving soaps, however. It was often the case in the early twentieth century that household soaps were made from tallows extracts from cattle bones.

To make a soluble soap, you must combine the fat with either sodium, ammonia, or potassium. Sodium carbonate is the basis of washing soda, the stuff you still put in your dishwasher, for example, or use to scrub a pan. One important stage in the history of soap development was when the eighteenth century chemist Nicolas Leblanc developed a process to extract sodium carbonate from ordinary salt.

Modern soap only became widespread and popular as a result of two things: germ theory and capitalism. It was only in the late nineteenth and early twentieth centuries that germ theory became dominant, finally overturning the old “miasma” theory that diseases spread through rotting matter and bad smells. The demand for soap thus began to rise, and in the days before antibiotics it was an essential item. So the manufacturers got to work. P&G’s White Soap was developed in 1878, called Ivory after a quotation from Psalm 45. As innovation in the product emerged, advertising followed. 

Artificial soaps began to be developed in the nineteenth century, but the creation of artificial detergents was spurred on by the shortage of fats during the First World War. Progress continued through the 1920s and 1930s and by the 1950s laundry detergent was widespread.  

The spread of soap also relied on advertising. We are often told that advertising is an exploitative medium, which invents useless fantasies to prey on our insecurities. But advertising is the industry that invented the idea of washing your hands in the bathroom. It’s a Good Habit, proclaimed posters for Pears’ Soap. Opera singers and actresses were used to promote the new habit. 

Soap was sold both as something that made you clean–targeting mothers especially — and as something that made you fresh and appealing. Katherine Ashenberg explains in her splendid book Clean: an unsanitized history of washing, that the 1920s was the final end of the culture where people neither noticed or minded each other’s smells very much. Close living in dense cities made it imperative for people to wash regularly. Listerine had been invented in 1879 giving, as Ashenberg says, a new name to an old problem. The arrival of women in the workplace made men increasingly interested in smelling fresh too.

We see the same hostility to progress today with the new drugs that help people lose weight. Some people will always think it was cruel and exploitative of advertisers to point out that some people had bad breath and that it killed their chances of romantic happiness. But none of them has decided this fraud is so big that they have stopped brushing their teeth. The classic ad copy for deodorant referred to “a subject too often avoided”. These issues weren’t invented for sales; the products and adverts were solving a problem no-one felt comfortable talking about.

Nor did the ploy work. Ashenberg notes the 1920s saw a drop in soap sales, as cleaner paved streets and roads were being built, electricity was installed, and people were moving to the city — all trends that took us away from dirt roads, coal fires and kerosene lamps. As machines made manual work lighter in the factory and the home, we became less sweaty and grimy. But soap survived, and remains as important as ever. Nothing else is so simple, cheap, and easy and so effective as removing unwanted germs and making us fresh and clean.