thallium

/thal-ee-uhm/US // ˈθæl i əm //UK // (ˈθælɪəm) //

铊,硫磺,铊的作用,汞

Definitions

n.名词 noun

1
Chemistry.
- : a soft, malleable, rare, bluish-white metallic element: used in the manufacture of alloys and, in the form of its salts, in rodenticides. Symbol: Tl; atomic weight: 204.37; atomic number: 81; specific gravity: 11.85 at 20°C.

Thallium is a rare metal, found in small quantities in some varieties of iron and copper pyrites, and in some lithia micas.
A stream of incandescent thallium-vapour passes between them, the magnified image of which is now seen upon the screen.
Light of one degree of refrangibility—that corresponding to this particular green—is emitted by the thallium-vapour.
If we add to the silver in our camera a bit of thallium, we shall obtain the light of both metals.
After waiting a little, we see that the green of the thallium lies midway between the two greens of the silver.