Liquid air-almost as cold as Neptune's moon
Q: At what temperature does air liquefy? --Abhishek Sarangan, Sharjah, United Arab Emirates
 A: A cold temperature: -321 degrees Fahrenheit (-196 Celsius). Few substances are colder. Hold a fresh
rose in a vat of grayish, steaming liquid air for a moment and then present it to an unsuspecting victim. Drop it
just before she grasps it and watch her amazement as the extraordinarily cold rose shatters like glass upon
impact.
[NASA] 1926, Goddard's first launch of a liquid-fueled rocket
We can't get gas that cold except by compressing it (3,000 pounds per square inch-200 times the atmospheric
pressure at sea level) and then allowing it to expand. The process requires several cycles to achieve a liquid
state. Eight hundred gallons of gaseous air yield one gallon of the liquid.
When first produced back in 1895, liquid air had little importance outside the laboratory. Now its byproduct--
liquid oxygen-is the third highest-volume chemical produced in the United States. We extract liquid oxygen
from liquid air by a series of distillations. Liquid-oxygen fueled rockets allow us to probe the frontiers of
space.
By the way, it gets even colder on Neptune's moon, Triton--down to -390 F.
(Answered by April Holladay, science correspondent, Mar. 6, 2002)
Further Surfing:
Purdue U: Liquid air demonstrations
Purdue U: Meltdown of hamburger grill with liquid oxygen
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