The extraction (as is the case with all the rare earths) is a matter of great difficulty.
The movements of the shaft are controlled by relays and electro-magnets which operate in response to the action of the subscriber whose telephone is fitted with a 'calling mechanism which, when the subscriber calls, earths the line a certain number of times for each figure in the number of the wanted subscriber.
Our regions will not be natural unless they mark out real discontinuities both of origin and affinity, and these we can only seek to explain by reference to past changes in the earths history.
Berzelius's investigation of the action of the electric current on salts clearly demonstrated the invaluable assistance that electrolysis could render to the isolator of elements; and the adoption of this method by Sir Humphry Davy for the analysis of the hydrates of the metals of the alkalis and alkaline earths, and the results which he thus achieved, established its potency.
These crude earths, yttria and ceria, have supplied most if not all of the " rare earth " metals.
