✦Chapter II · §3— quattuor proprietates vitri uranici
Four Things the Lamp & the Cabinet Will Show You
I
It is a quiet custard by daylight.
In the south window the cup reads pale citron, barely warmer than oatmeal — easy to mistake for plain Edwardian pressed-ware until the curtain is drawn.
Spectrum 365 nm
II
Under blacklight, it does not glow — it announces.
Two grams of uranium oxide per kilo of batch, fluorescing at 525 nanometres; the colour reads truer than any phosphor mankind has since improved upon.
Emission 525 nm
III
The pressed facets do the second half of the work.
Hobnail, daisy-and-button, scalloped rim — each cut splinters the fluorescence into discrete sparks, so a single goblet behaves like fourteen smaller lamps.
Pattern Hobnail, c. 1889
IV
It will, very slightly, set off your Geiger counter.
A typical Whitmore & Vale tumbler registers near 0.5 µSv/h at contact — harmless on the shelf, but the needle moves, and that is half of the romance.