| 摘要 |
<p>An elapsed time indicator which provides a visual indication after a fixed period of time has elapsed, the visual indication being brought about, in use, by dissolution of a soluble part of the indicator in an aqueous based solvent, such as water. The soluble part of the indicator may comprise a composite body having a soluble filler, such as phosphate glass, which has a density greater than that of the aqueous based solvent and a non-soluble component having a density less than that of the aqueous based solvent. In use the soluble part of the indicator is dissolved in the aqueous based solvent until the composite body is of a density which causes it to rise and float.</p> |
