Patent ID: 7011445

Claim:
A reusable maximum/minimum thermometer comprising an expansion liquid ( 42 ) which expands or contracts in response to changes in temperature, a transfer liquid ( 48 ) which is moved in response to the expansion or contraction of the expansion liquid and which is substantially immiscible with the expansion liquid, two indexes ( 44 , 51 ), and a temperature scale associated with the maximum/minimum thermometer, wherein the indexes are constructed from a plastic material into which has been mixed and/or melted a quantity of magnetic powder such as iron filings, magnetite (Fe 3 O 4 ), and/or strontium ferrite, and wherein the indexes have a density less than that of the transfer liquid, are able to float on the surface of the transfer liquid, and are moved by the transfer liquid into resting positions whereby maximum and minimum temperatures are read off the temperature scale, and wherein the transfer liquid is a mercury free solution selected from the group consisting of inorganic compounds, organometallic compounds, organic liquids, and ionic liquids.