Almost it seemed as though the soft delicate air through which it passed, the exquisite beauty of the sloping landscape and old garden over which it traveled, had had a Rarefying influence upon the sound itself, and had mellowed its tones into a strain of the most perfect music throbbing with harmony and dying away in faint, delicious murmurs.
"The New Tenant"
E. Phillips Oppenheim
I am told these tempests are frequent in The Mountains, no doubt arising from the intense heat Rarefying the air.
"Travels in the Great Desert of Sahara, in the Years of 1845 and 1846"
James Richardson
When these fortresses are thickly peopled, the continual motion within tends, I think, to mix up this gas with the air above; while the numerous fires lighted within, by Rarefying that below, tend to draw down a regular supply of the atmospheric air from above for the benefit of the inhabitants.
"Rambles and Recollections of an Indian Official"
William Sleeman