These horses are called Arvak and Alsvid, and under their withers the gods placed two skins filled with air to cool and refresh them, or, according to some ancient traditions, a refrigerant substance called isarnkul.
"The Elder Eddas of Saemund Sigfusson; and the Younger Eddas of Snorre Sturleson"
Saemund Sigfusson and Snorre Sturleson
It is a consideration, Sir Poet, which may serve as a refrigerant for their ardour.
"Colloquies on Society"
Robert Southey
13. "This almost never fails to prove a refrigerant to passion."
"The Grammar of English Grammars"
Goold Brown