Assertion: thorium's use | /r/CapableOf | make practical
Facets:
value: in 1923
type: TEMPORAL
value: by irving langmuir
type: OTHER
Source sentences:
text: A common type of directly heated cathode, used in most high power transmitting tubes, is the thoriated tungsten filament, discovered in 1914 and made practical by Irving Langmuir in 1923.