Assertion: artificial cryolite | /r/HasProperty | contained many objectionable impurities
Facets:
value: heretofore
type: TEMPORAL
Source sentences:
text: Heretofore artificial cryolite has contained many objectionable impurities or the process has caused a waste of material or is manufactured by a dry process with the necessity of a preferable temperature of 7000 F. to 9500