Assertion: calcium carbonate's property | /r/ObjectUse | used in second world war bombsights
Facets:
value: commercially
type: MANNER
Source sentences:
text: This property of birefringence or double refraction has been used commercially, most notably in Second World War bombsights where the amount of separation of the two images was used to estimate distances, but this is a tiny part of the many ways that calcium carbonate has found its way into our lives.