Colour-electric, magnetic fields

The colours of the transition metal ions and their complexes are, in fadt, due to electronic transitions involving the d electrons. The d shell in an atom or ion is five-fold degenerate, i.e. there are five d orbitals which are equal in energy in the absence of an external magnetic or electric field. An electron... 

Davy s paper on the electrical phenomena exhibited in vacuo announced the discovery of the mercury arc of a bright green colour, and of great density , also a feebler yellow discharge. in tin vapour (he did not try sodium). A short paper on a new phenomenon of electro-magnetism announced the discovery of the rotation of mercury round a wire carrying a strong current in a nu etic field. 

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