1823

Liquefaction of gases

• Michael Faraday showed the relation between liquids
• and their gases, liquifying chlorine, euchlorine,
• nitrate of ammonia, hydrochloric acid,
• sulfurous acid, hydrogen sulfide, and carbonic acid
• by drawing gases into bent glass tubes,
• or by sealing liquids in bent glass tubes
• including in them iron and platinum catalysts
• or a little water or mercury at one end,
• and vaporizing them by heating,
• and cooling by evaporation or salted ice.
• He made these experiments with considerable risk
• as tubes of gases under pressure spontaneously exploded.

Processes

• You can liquify ammonia gas by compressing it,
• which releases heat,
• or you can heat liquid ammonia to convert it to a gas.
• If you let liquid ammonia evaporate under low pressure,
• it sucks heat from its environment,
• and if you cool that gaseous ammonia it condenses back to a liquid.
• If you release a condensed gas to the environment,
• in expanding, it sucks heat from its environment,
• and if you compress the gas, it releases its heat.
• Therefore, we see a relationship
• between the state of a chemical
• and the energy latent in it.

Liquefaction of water

• It’s raining in Seattle.
• These clouds were raised from the Pacific
• and are blowing over us
• toward a low-pressure zone near Omaha.
• Great cummulus clouds move grandly
• to reveal random patches of blue sky.
• When I say “it’s raining,”
• I mean that we see scattered wet spots.
• Innumerable drops speckling windows, windshields,
• yards, roofs, trees waving in a gentle breeze,
• sidewalks, baseball caps, and bluejeans
• evaporate and blow away.