AS he turned to go on, he spat speculatively. There was a sharp, explosive crackle that startled him. He spat again. And again, in the air, before it could fall in the snow, the spittle crackled. He knew that at fifty below spittle crackled on the snow, but this spittle crackled in the air. Undoubtedly it was colder than fifty below- how much colder he did not know.

-Jack London, To Build A Fire-