About: http://webisa.webdatacommons.org/48591782

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Early refrigeration units used highly toxic gases such as ammonia, sulfur dioxide, and methyl chloride.
http://www.w3.org/ns/prov#wasQuotedFrom	wisegeek.com