|Table of Contents for Caveman Chemistry: 28 Projects, from the Creation of Fire to the Production of Plastics|
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280. How soap is made from olive oil or tallow
Spread well burnt ashes from good logs over woven wickerwork made of withies, or on a thin-meshed strong sieve, and gently pour hot water on them so that it goes through drop by drop. Collect the lye in a clean pot underneath and strain it two or three times through the same ashes, so that the lye becomes strong and colored. This is the first lye of the soapmaker. After it has clarified well let it cook, and when it has boiled for a long time and has begun to thicken, add enough oil and stir very well. Now, if you want to make the lye with lime, put a little good lime in it, but if you want it to be without lime, let the above-mentioned lye boil by itself until it is cooked down and reduced to thickness. Afterwards, allow to cool in a suitable place whatever has remained there of the lye or the watery stuff. This clarification is called the second lye of the soapmaker. Afterwards, work [the soap] with a little spade for 2, 3 or 4 days, so that it coagulates well and is de-watered, and lay it aside for use. If you want to make [your soap] out of tallow the process will be the same, though instead of oil put in well-beaten beef tallow and add a little wheat flour according to your judgment, and let them cook to thickness, as was said above. Now put some salt in the second lye that I mentioned and cook it until it dries out, and this will be the afronitrum for soldering.
Nothing in the history of humankind, save for the cultivation of noble fire itself, can compare to the discovery of soap. This is how one of the Author's pyrophilic alter-egos would undoubtedly have begun the present chapter. Lucifer would have described a venerable history stretching back to the third millennium BC, when concoctions of ashes and fat were recorded on Sumerian clay tablets. In order to claim that these concoctions were soap, however, he would have to overlook the fact that these tablets make no mention of any detergent properties these mixtures might have had. He would have to find it unremarkable that pharoic Egypt and the empires of Greece and Rome failed to appropriate such a useful material, but relied instead on urine, various plants, clays, potash, and soda for doing the laundry. He would have to ignore the extensive Roman literature on personal hygiene, which describes the process of oiling the body and scraping the dirty oil off with an instrument called a strigil. No, an ancient origin for soap simply does not wash.
The Samsonites would probably prefer the "old Roman legend" which places the invention of soap in the hands of the Goddess Athena. Runoff from animal sacrifices made at her temple on Sapo Hill, so the story goes, resulted in the accumulation of ashes and animal fat in the river below. Women washing clothes in this river found that their clothes came out whiter and brighter than usual and eventually traced the suds back to their source. But why, we might wonder, would the Romans have had an "old legend" about a material which they did not use in classical times? The Author has yet to find an attribution for this oft-repeated tale and it remains of doubtful historical authenticity. Even given his penchant for making up fantastic scenarios, the Author recoiled from this one on chemical grounds. You see, soap-making requires the concentration of alkali and fat, not the dilution which would have resulted from sacrificial runoff. If you ask me, we had better flush this just-so story right down the drain.
Unktomi and his ilk might have spun a similarly fantastic tale, tracing soap back to Phoenician traders of 600 BC. This claim, repeated by no less an authority than the Encyclopedia Britannica, is often attributed to Pliny the Elder's Natural History. Indeed, this text of the first century AD introduces the word sapo into Latin:
Soap [Sapo] is also good, an invention of the Gallic provinces for making the hair red. It is made from suet and ash, the best is from beech ash and goat suet, in two kinds, thick and liquid, both being used among the Germans, more by men than by women.
This is the only mention of the word sapo in all of Pliny and no mention is made either of the Phoenicians or of the aforementioned date. No mention is made of using the stuff for washing up. We might be tempted to conclude that the presumed soap was simply an exotic cosmetic whose name became attached to a material of later invention, were it not for two observations. First, Pliny says that this sapo is made from goat tallow and ashes, which, in and of itself would not be conclusive. But he goes on to say that it comes in two varieties, liquid and solid, and the fact of the matter is that soap made from potash turns out to be a liquid while that made from soda is a solid. We would do well, then, not to throw our Pliny out with the bath water.
Nevertheless, we should be cautious in supposing the widespread use of soap in the first millennium AD. Claims of soap-making at Pompeii in the first century continue to be made, despite the fact that Hoffman's analysis of this supposed soap in 1882 showed it to be nothing more than fuller's earth, a kind of alkaline clay described by Pliny for the laundering of clothes. If soap had been around you would think that it might have been mentioned in the Stockholm Papyrus, that second-century collection of dye recipes quoted in Chapter 12, but while it gives instructions for washing wool with vinegar, ashes, and plants, it makes no mention of anything resembling soap. The second-century physician Galen uses the word sapo to describe an exotic material made from goat tallow and ashes which is good for washing things. While this is undoubtedly soap, his descriptions occupy less than a few sentences in the thousands of pages which make up his complete works. French soap is described by Theodorus Priscianus of the fourth century as a material for washing the head. Italian soap-makers of the seventh century were organized into craft guilds and the profession of soap-boiler is mentioned in Charlemagne's Capitulare de Villis of 805 AD. Frustratingly, all of the first millennium references to soap are brief at best and vague at worst. We must conclude that while soap had come to Rome from the provinces prior to the second century, as far as most people were concerned, it was "no soap for you."
The first detailed recipe for what is unmistakably soap appears in the twelfth century Mappae Clavicula. You will recall from Chapter 16 that this work, traditionally attributed to Adelard of Bath, is a collection of trade secrets for painters and craftsmen. The inclusion of recipes for soap tells us two things about the status of soap at that time. First, soap must not have been widely available; otherwise Adelard would simply have picked it up at the market. Second, soap was familiar enough that no explanations are given for its use. He mentions its use as a soldering flux, but given the importance of textiles in the rest of the work, the use of soap for washing fabrics seems likely. Moreover a second recipe, that for "French" soap, says that berries are used to color it red, which perhaps explains Pliny's claim that the Gauls use it to color their hair red.
Early centers for soap manufacture were Marseilles, by the ninth century, Venice, by the fourteenth century, and Castile by the fifteenth century. In addition to these internationally-traded soaps made principally from olive oil, domestic soaps made from tallow were produced in Bristol, Coventry, and London. The scale of the industry was increasing; in 1624 the Corporation of Soapmakers at Westminster was granted a royal patent to produce 5000 tons of soap per year. By the eighteenth century, soap was a common domestic item. The Dictionaire Oeconomique of 1758 describes:
SOAP, a Composition made of Oil of Olive, Lime, and the Ashes of the Herb Kali or Saltwort; the chief use of Soap is to wash and cleanse Linnen: There are two sorts thereof, which are distinguished by their Colours, viz. White and Black Soap.
The Dictionaire goes on to describe a process little changed from that of the Mappae Clavicula. White soap is solid, made from lime and soda, that is, from sodium hydroxide; black soap is liquid, made from lime and potash, that is, from potassium hydroxide stained by residual charcoal.
Demand for soap had increased rapidly during the eighteenth century as the textile industry became increasingly industrialized. And because soap makers depended on supplies of soda, lime, and potash, they were a major driving force in the industrialization of chemical manufacture. In fact, two of the oldest surviving chemical companies in the world started out in the soap trade. In 1806 William Colgate began making soap and candles in New York. In 1837 William Proctor and James Gamble went into partnership to manufacture soap and candles in Cincinnati.
But I suppose that all this is too boring to hold the attention of most readers, with their remote-controls, their instant messages, and their personal digital gizhatchies. They aren't satisfied with vacuous little jingles, breezy little games, and tedious little exercises. No, they'd rather lap up wild tales about Chinese laundresses, or itinerant Taoists, or tail-sniffing dog conventions. If you want anyone to pay attention to you nowadays, you have to pretend to be Elzabath, the wife of a French tallow chandler, working your fingers to the bone what with the cooking and the cleaning and the interminable rendering of fats for the candle business.
Normally, you render fat by boiling meat trimmings in salt water, with some berries thrown in for color. You allow the melted tallow to float to the top and upon cooling, the tallow hardens into a block and can be lifted out of the pot. But on this particular day, you've got a splitting headache, a crying baby, and a stinking pile of laundry that stretches back to last week. And all your husband can do is to go on and on about how nobody ever notices him down at the Chandler's Guild. You go to lift the tallow out of the pot and—can you believe it—instead of a block you find nothing but a pot of red goo. Your husband is no help at all. "What am I supposed to do with this, make jelly candles?" he snorts. You've had just about as much as you can take. "Maybe you'd like to wear it!" You grab a handful of goo and slap it right on top of his head. He stands there looking like a stuffed goose with gravy and then he suddenly breaks out laughing. You can't help but laugh too. In retrospect you figure out that between the crying, the cleaning, and the complaining, you must have accidentally added potash to the pot instead of salt. You get him cleaned up and pack him off to his guild meeting. When he returns you make nice to him. "How was the meeting, Sweetie?" "Now 'Bath, you know the first rule of Chandler's Guild is that you don't talk about Chandler's Guild." But it seems that red hair is suddenly all the rage and so you add soap as a sideline to the candle business; the rest is history.
Not that such a thing ever happened to me; I'm just a figment of the Author's imagination, in case you've forgotten. So don't go attributing this little soap opera to Aristotle or Lucretius or anyone other than the Author.
Reference , p. 12.
Reference , Book XXVIII, li.
Reference , p. 308.
Reference , De Compositione Medicamentorum Secundum Locos, ii, Kuhn Book XII, p. 589.
Reference , De Methodo Mendendi, viii, Kuhn Book X, p. 569.
Reference , p. 307.