Abstract: A portable heat source that may be used to warm food, beverage or other supplies. The heater contains a heat-producing composition that is a solid that may be stored for long periods of time, and activated by addition of water or an aqueous solution. Heat-producing compositions contain an acidic anhydride, an acidic salt, a basic anhydride or a basic salt. Preferred heat-producing compositions contain a mixture of an acidic anhydride or salt together with a basic anhydride or salt, such that addition of water to both acidic and basic anhydrides produces heat as well as acid and base respectively; subsequent reaction of the acid and base produces additional heat, as well as a safe, neutral product that is easily disposed. The invention further consists of means and methods for regulating the rate of heat production in heaters by the addition of inert additives to heat-producing compositions and the application of processing methods that regulate access of water to heat-producing compounds.

Abstract: This invention is a portable heat source that may be used to warm food, beverage or other supplies. The heater material is a solid that may be stored for long periods of time, and activated by addition of water or an aqueous solution. The heater consists of an acidic anhydride or salt together with a basic anhydride or salt, such that addition of water to both acidic and basic anhydrides produces heat as well as acid and base respectively; subsequent reaction of the acid and base produces additional heat, as well as a safe, neutral product that is easily disposed. The invention further consists of means to regulate the rate of heat production by the use of additives and processing methods, so that heat is produced at a rate compatible with the rate at which the food or other materials can absorb the heat. The invention further consists of devices incorporating the materials to be heated in an advantageous arrangement with the heater composition.