Sunday, January 24, 2010

BioMetals 2010

Online registration for 7th International Biometals Symposium (BioMetals 2010) is now open. The meeting will take place in Tucson, Arizona, USA, July 25—30, 2010.

Sessions are planned on Arsenic: Toxicity and Transformation; Siderophores and Iron Transport; Interplay of Metals; Metals and Gene Regulation; Metals in Disease and Metal Transport. See the current list of invited speakers.

The conference is limited to 200 participants, so early registration is recommended.

Monday, January 18, 2010

Metals in ancient Egypt

The al of “alchemy” is an Arabic article, but what about the rest of the word? Wikipedia mentions theories favouring Egyptian, Greek or Persian origin of the root. Whatever the etymology, it looks like ancient Egyptians knew quite a lot of chemistry.

This table of Egyptian symbols for the metals (don’t think any of them is in Unicode) misses two or three metals known to ancient Egyptians. According to Hamed A. Ead,

tin was used in the manufacture of bronze, and cobalt has been detected as a coloring agent in certain specimens of glass and glaze. Neither metal occurs naturally in Egypt, and it seems probable that supplies of ore were imported from Persia.
Mercury <...> is stated to have been found in Egyptian tombs of from 1500—1600 B.C.
Perhaps not surprisingly, the terminology used in ancient Egyptian chemical literature sometimes was deliberately misleading:
The use of the trade names for the purpose of concealing the character of the substance used where secrecy seemed desirable was not unknown at that period.
The secret names as the later alchemists used extensively: “blood of the serpent”, “blood of Hephaistos”, “blood of Vesta”, “seed of the lion”, “seed of Hercules”, “bone of the phyasimian”, etc.
The term “blood of the dove” used in the papyrus, von Lippmann has identified from other sources as meaning red lead or sometimes cinnabar.

Saturday, January 09, 2010

Below minus forty

Cold snap, you say? I do remember one New Year’s Day when the temperature in the Moscow region dropped below −40°. (Celsius or Fahrenheit? In this particular case, it’s the same: −40 °C = −40 °F = 233.15 K.) On 1 January 1979, we woke up in the (late) morning only to discover that we are stuck without any tea or hot food. We couldn’t switch on the gas cooker, which was running on propane/butane mixture. Why? As explained in this useful guide,
When the temperature of the liquids falls below its current boiling point the pressure inside the canister will no longer drive vapour out.
The boiling point of butane is −0.5 °C and that of propane is −42 °C; the temperature outside was below −42 °C, and the gas canisters were outside!

My mum called for a friendly neighbour who was better equipped than us. We kids did not worry too much about a guy warming up a gas canister with a blow torch. Anyway, everything went just fine and we had a wonderful day.