Good question. Here is a SWAG. Well, maybe not so scientific.

1. Gold (Au) is exceedingly dense, ~19 g/cm³, as is mercury (Hg), ~14 g/cm³, and lead (Pb) floats on Hg.

2. Both Au and Hg are highly reflective, but Pb quickly dulls.

3. Au is soft as butter, and the alchemists knew how to make it into sheets 100 nm thin. (One can continue the process until the gold is a transparent greenish, useful for filters but not for gilding.) Mercury is not merely soft, but liquid.

4. What might have been the biggest red herring is that Hg dropped onto Au dissolves into it in seconds! At first, the Hg leaves a silvery-colored stain... but in a matter of days, the stain disappears, leaving apparently unadulterated gold.

   Using Archimedes' method to check purity of Au can fairly easily show if Au is adulterated with less dense Ag, ~10 g/cm³, but the more-dense Hg could be added in small amounts, appearing to increase the weight of gold without a *perceptible8 decrease in density.

   A mountebank would think, "Eureka! Drop some mercury on gold, wait a few days, and I've made gold from mercury"... until some wise-guy heats the gold, distilling off the Hg (and slowly poisoning all in the assay office).

Good question. Here is a SWAG. Well, maybe not so scientific.

1. Gold (Au) is exceedingly dense, ~19 g/cm³, as is mercury (Hg), ~14 g/cm³, and lead (Pb) floats on Hg.

2. Both Au and Hg are highly reflective, but Pb quickly dulls.

3. Au is soft as butter, and the alchemists knew how to make it into sheets 100 nm thin. (One can continue the process until the gold is a transparent greenish, useful for filters but not for gilding.) Mercury is not merely soft, but liquid.

4. What might have been the biggest red herring is that Hg dropped onto Au dissolves into it in seconds (as I found when I got some on a ring)! At first, the Hg leaves a silvery-colored stain... but in a matter of days, the stain disappears, leaving apparently unadulterated gold (as I also found... BTW, the amalgam is safe, not releasing Hg vapor).

   Using Archimedes' method to check purity of Au can fairly easily show if Au is adulterated with less dense Ag, ~10 g/cm³, but the more-dense Hg could be added in small amounts, appearing to increase the weight of gold without a *perceptible8 decrease in density.

   A mountebank would think, "Eureka! Drop some mercury on gold, wait a few days, and I've made gold from mercury"... until some wise-guy heats the gold, distilling off the Hg (and slowly poisoning all in the assay office).

Good question. Here is a SWAG. Well, maybe not so scientific.

1. Gold is exceedingly dense (~19 g/cm³), as is Hg,(~14 g/cm³), and Pb floats on it.

2. Both Au and Hg are highly reflective, but Pb quickly dulls.

3. Gold is soft, and the alchemists knew how to make it into sheets 100 nm thin. (One can continue the process until the gold is a transparent greenish, useful for filters but not for fold lettering.) Mercury is not merely soft, but liquid.

4. What might have been the biggest red herring is that Hg dropped onto Au dissolves into it in seconds! At first, the Hg leaves a silvery-colored stain... but in a matter of days, the stain disappears, leaving apparently unadulterated gold.

   Using Archimedes' method to check purity of Au can fairly easily show if Au is adulterated with less dense Ag, ~10 g/cm³, but the more-dense Hg could be added in small amounts, appearing to increase the weight of gold without a *perceptible8 decrease in density.

   Eureka! Drop some mercury on gold, wait a few days, and you've made gold from mercury... until some wise-guy heats the gold, distilling off the Hg (and slowly poisoning all in the assay office).

Good question. Here is a SWAG. Well, maybe not so scientific.

1. Gold (Au) is exceedingly dense, ~19 g/cm³, as is mercury (Hg), ~14 g/cm³, and lead (Pb) floats on Hg.

2. Both Au and Hg are highly reflective, but Pb quickly dulls.

3. Au is soft as butter, and the alchemists knew how to make it into sheets 100 nm thin. (One can continue the process until the gold is a transparent greenish, useful for filters but not for gilding.) Mercury is not merely soft, but liquid.

4. What might have been the biggest red herring is that Hg dropped onto Au dissolves into it in seconds! At first, the Hg leaves a silvery-colored stain... but in a matter of days, the stain disappears, leaving apparently unadulterated gold.

   Using Archimedes' method to check purity of Au can fairly easily show if Au is adulterated with less dense Ag, ~10 g/cm³, but the more-dense Hg could be added in small amounts, appearing to increase the weight of gold without a *perceptible8 decrease in density.

   A mountebank would think, "Eureka! Drop some mercury on gold, wait a few days, and I've made gold from mercury"... until some wise-guy heats the gold, distilling off the Hg (and slowly poisoning all in the assay office).