| 摘要 |
A timing device for visually determining the passage of a preselected period of time including an inverted U-shaped tube having opposed ends with at least one of the opposed ends having a reservoir for storing a reactant or an indicator, transport means extending from the reservoir to the other of the opposed ends of the tube for transporting at least one of the reactant or the indicator until they contact each other, a reactant, and an indicator which when in contact with the reactant via the transport means emits an observable change in a property wherein the minimum length of the period of time corresponds to the time it takes for the reactant and indicator to contact each other.
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