Assertion: hydrogen fluoride | /r/HasProperty | evolved as form
Facets:
value: partly
type: DEGREE
value: directly
type: MANNER
Source sentences:
text: The hydrogen fluoride and silicon tetrafluoride are partly evolved directly as vapours and partly form fluosilicic acid which, under the influence of heat, decomposes again into volatile SiF4 and HF, leaving the reaction vessel together with the water vapour.