1843

Erbium

• Mosander found two impurities,
• both oxides,
• in his oxide of yttrium—one yellow
• and the other rose.
• Having named yttrium from the first syllable
• of the village where it was found, Ytterby,
• and the second after the second syllable,
• he named the third after the trailing letters, erb.
• Mosander named the rose oxide terbia,
• and the yellow oxide erbia,
• but Berlin named terbia erbia,
• so Marc Delafontaine named erbia terbia.

Atomic number 68

• Erbium doping is used in amplifier-lasers
• for fiber optics and long-distance transmission.
• Erbium-doped yttrium aluminium garnet lasers
• are useful in surgery and in dentistry.
• Erbium oxide’s pink color makes it useful
• in glass, glazes, porcelain, and cheap jewellery.
• Erbium improves the workability and increases
• the softness of vanadium alloys.

Tweedledee and Tweedledum

• They stick together, with
• similar desires, similar fears.
• Instead of poking fun at them,
• let’s respect them as equals.
• Our imaginary friends
• don’t laugh at themselves.