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:
“The true picture of the past flits by. The past can be seized only as an image which flashes up at the instant when it can be recognized and is never seen again.”
—Walter Benjamin (1892–1940)
“How the cold creeps as the fire dies at length
How drifts are piled,
Dooryard and road ungraded,
Till even the comforting barn grows far away,
And my heart owns a doubt
Whether ‘tis in us to arise with day
And save ourselves unaided.”
—Robert Frost (1874–1963)
“... [Washington] is always an entertaining spectacle. Look at it now. The present President has the name of Roosevelt, marked facial resemblance to Wilson, and no perceptible aversion, to say the least, to many of the policies of Bryan. The New Deal, which at times seems more like a pack of cards thrown helter skelter, some face up, some face down, and then snatched in a free-for-all by the players, than it does like a regular deal, is going on before our interested, if puzzled eyes.”
—Alice Roosevelt Longworth (1884–1980)