Field of Science

Sweet leads


Sugar of Lead Poison Bottle
Originally uploaded by john4kc


Horror of horrors - the Romans used lead to sweeten their fruit. No wonder Rome fell! Except that I was willing to read a 1883 paper (in German with healthy helpings of Greek and Latin) to discover that it may be lead and it may be sweet, but the lead doesn't lead it to be sweet.

In a time when mercury was regularly used as a remedy for maladies as serious as syphilis and as commonplaces as constipation, it doesn’t surprise me that lead compounds were in the pharmacopeia. (In all fairness, some modern antibiotics and most chemotherapy agents are at least as toxic as these less old remedies; they just have a better risk-benefit ratio.) Sugar of lead, or as it’s called in the 19th century medical literature, saccharum saturni, is lead acetate: Pb(CH3COOH)2. It was once prescribed for intestinal troubles, an odd choice, since one symptom of acute lead poisoning is an upset stomach. Lead poisoning is also known as painter's colic.

Sugar of lead really is sweet, roughly as sweet per spoonful as sugar. In the 18th and 19th century, lead shot was often dropped into bottles of port, purportedly to make it sweeter - though the more likely effect is anti-bacterial. Why? Lead does dissolve well in alcohol and juices (crystal decanters to store your port are a bad idea) - but I can't find anything that suggests solutions of lead ions are sweet.

The Romans were reputed to use lead acetate as a sweetener. They produced a syrup called sapa by boiling down mildly fermented grape juice in kettles made from lead alloys. (The hydrates of lead acetate are far less soluble in alcohol solutions - you are more likely to get a suspension of crystals in the syrup.) I am suggesting that it’s unlikely that the syrup was sweet because of the lead acetate it certainly contained. An 1883 analysis of sapa produced according to recipes dating from the classical Roman period, in kettles of similar metallic content to those found at Pompeii and other sites, suggested that the lead content of sapa was roughly 850 mg per liter. The equivalent amount of table sugar would be roughly a teaspoon - hardly enough to taste sweet in a liter of liquid. On the other hand, the sugars (glucose and fructose) in the concentrated grape must are the equivalent of 1 cup of table sugar per liter and would certainly swamp any sweetness coming from the lead acetate. It's still not all that sweet. To get a sense of how sweet this is, simple syrup, which has similar culinary uses to sapa, has about 4 cups of sugar in a liter.

I still wouldn't use sapa to poach my pears, but I think it unlikely that the sweet taste of sapa has much to do with lead.


Photo is c. 2009 John4kc. Used with permission.

6 comments:

  1. My grandmother would send my father to the drugstore for fifteen cents of sweet lead to treat their poison ivy.

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    1. Darla Chapman TaylorSeptember 10, 2012 at 8:36 PM

      Funny. I was talking to my mother today and she is now 81. she told me the same thing that my grandmother would use the same thing for her poison ivy. Pretty interesting. i told her i would have to look this up. she also said she asked a pharmacist if he had ever heard of it and he he asked what?,and then laughed as my mother proceeded to tell him the story.

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  2. We laugh at nineteenth century doctors prescribing mercury and lead based compounds as treatments for disease, but is modern medicine with its deadly concoctions like statin drugs and other bizarre chemical potions whose alleged efficacy is based on biased "studies" conducted by the manufacturers themselves, and pseudo scientific, overly simplistic paradigms created by marketing firms,any better?

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  3. My father used to use sugar of lead in a liquid form for athlete's foot - a condition where cracks in the crevices between the toes occur, causing itching, etc. I have a chronic condition that does the same thing to my ears at any point where there is a "crevice" such as the top of my ear or just at the entrance and they also develop a scale-like condition where the skin forms an excess and I can peel it off. I keep thinking about my dad and that little old bottle of lead acetate solution,,,,and despite all the 'warnings' I am very very tempted to give it a try. God knows I've tried EVERYTHING else.

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