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:
“For an instant I see the sky, the different skies, then they turn to faces, agonies, loves, the different loves, happiness too, yes there was that too, unhappily.”
—Samuel Beckett (1906–1989)
“The hand holds no chalk
And each part of the whole falls off
And cannot know it knew, except
Here and there, in cold pockets
Of remembrance, whispers out of time.”
—John Ashbery (b. 1927)
“You’re nothing but a pack of cards!”
—Lewis Carroll [Charles Lutwidge Dodgson] (1832–1898)