Abstract: A particulate composition producing an endothermic reaction when mixed with water, and a cold pack containing such a composition, and water isolated therefrom until the intended time of use. The composition consists essentially of, in parts by weight, about 65 to about 130 parts urea, about 35 to about 80 parts hydrated sodium acetate (Na C.sub.2 H.sub.3 O.sub.2 .multidot.3H.sub.2 O), about 18 to about 40 parts potassium chloride, potassium nitrate, or mixtures thereof, about 18 to about 30 parts ammonium chloride, and about 6 to about 10 parts quar gum. A cold pack comprises an outer sealed, flexible, impermeable enclosure containing the composition, and an inner sealed, flexible, impermeable, easily ruptured enclosure containing about 85 to about 140 parts by weight water. The pack reaches and maintains a temperature of about -7.degree. C for up to 30 minutes, and is moldable to conform to the surfaces being cooled.

Abstract: A particulate composition producing an exothermic reaction when mixed with water, and a hot pack containing such a composition, and water isolated therefrom until the intended time for use. The composition consists essentially of, in parts by weight, about 40 to about 90 parts anhydrous calcium chloride, about 12 to about 25 parts anhydrous sodium acetate, and about 5 to 15 parts calcium oxide. A hot pack, per the invention, comprises a sealed, impermeable, flexible outer enclosure containing the composition, and a sealed, impermeable, flexible, easily ruptured inner enclosure containing about 40 to about 90 parts by weight of water. The proportions of the elements of the particulate composition will vary somewhat in accordance with the objectives of the hot pack in which the composition is applied. When the contents of the hot pack are activated, it will gradually reach, maintain and be limited to be predetermined safe temperature.

Abstract: A heat transfer package characterized by a shell-like container within which a receptacle is nested and to which said receptacle is integrally connected. The shell-like container features an upstanding self-stabilizing outer wall section provided with air escape holes and so constructed to enable the wall section to be axially compressed yet having the property to retain its vertical stability on compression. Heat transfer means are included within said outer shell in a separated relation to the material within said receptacle and so arranged to be activated by an axial compression of said outer shell. On an axial compression of said shell, not only is there produced an activation of the heat transfer medium embodied therein but the wall section is collapsed into itself in a locked position while the package is resting on its base.

Abstract: A portable heat transfer unit in the form of a chemical package includes at least two chemical heat transfer materials separated by a chemical buffer material. In their dry state and in their separated condition the chemical heat transfer materials will remain inactive. The introduction of an activating fluid will cause the respective materials to individually and jointly react and interact to produce an extended heat transfer effect.