Assertion: cesium's application | /r/CapableOf | exist for caesium
Facets:
value: until the 1920s
type: TEMPORAL
Source sentences:
text: Very few applications existed for caesium until the 1920s, when it came into use in radio vacuum tubes, where it had two functions; as a getter, it removed excess oxygen after manufacture, and as a coating on the heated cathode, it increased the electrical conductivity.