An instant cold pack is a device that consists of two bags, one containing water, which is inside a second bag containing ammonium nitrate. When the inner bag is broken by squeezing the package, the ammonium nitrate is allowed to dissolve in the water in an endothermic reaction. This reaction absorbs heat from the surroundings, quickly lowering the pack's temperature.
Instant cold packs are a convenient direct replacement for crushed ice used as first aid on sport injuries. It is also important not to refrigerate before activation. This may result in frostbite if used for prolonged periods of time.
For safety reasons, instant cold packs have recently been developed without ammonium nitrate.
Famous quotes containing the words instant, cold and/or pack:
“There is no instant of time when one creature is not being devoured by another. Over all these numerous races of animals man is placed, and his destructive hand spares nothing that lives. He kills to obtain food and he kills to clothe himself; he kills to adorn himself; he kills in order to attack and he kills to defend himself; he kills to instruct himself and he kills to amuse himself; he kills to kill. Proud and terrible king, he wants everything and nothing resists him.”
—Joseph De Maistre (1753–1821)
“The eyes of strangers
Are cold as snowdrops....”
—Philip Larkin (1922–1986)
“The savage soul of game is up at once—
The pack full-opening various, the shrill horn
Resounded from the hills, the neighing steed
Wild for the chase, and the loud hunter’s shout—
O’er a weak, harmless, flying creature, all
Mixed in mad tumult and discordant joy.”
—James Thomson (1700–1748)