Abstract: A solid has a reversibly invisible/visible thermochromic internal construction enclosed therein which is composed of a solid made of a transparent resin and a fluorescent internal construction showing the internal structure of the solid enclosed therein, wherein a reversible thermochromic layer containing a reversible thermochromic composition is formed on the surface of the solid, or the transparent resin contains a reversible thermochromic composition.

Abstract: A method for energizing an energization-operated toy element in which an electric double layer capacitor is employed as energization means for energizing a toy element which is operated upon application of low voltage, the capacitor is charged upon reception of a current from a DC power source, and the charged electric power is used to energize a toy load as a discharge current to operate the toy element. An energization-operated toy which comprises an energization heating color changing element provided with an energization resistant heating member for generating heat upon application of the DC voltage and a thermal color changing layer disposed in contact with or close to the heating member, energization means consisting of an electric double layer capacitor for generating heat by supplying the discharge current to the energization resistant heating member, and a power source for supplying the DC voltage from 0.5 V to 9.0 V to the capacitor.

Abstract: A thermochromic laminate member comprises a thin transparent iridescent film laminated on a thermochromic layer 2, and exhibits rainbow-color pattern. The thermochromic layer shows reversible change between a first colored state and a second colored state by a temperature change.

Abstract: A new reversible temperature indicating composition for use in temperature indicating instruments is diclosed which is capable of accurate temperature indication in a variety of colors and characterized by a minimum range of hysteresis so that the marking drawn in this composition can decolor at or close the temperature at which its coloring takes place. In addition, the composition can provide a wide variety of hues and can be readily prepared. These and other advantages are provided by the inclusion as a main ingredient of an ester compound having .DELTA.T value, defined .DELTA.T=melting point--clouding point, in the range under 3.degree. C., the value that determines a desirably small range of hysteresis.