| 摘要 |
934,516. Thermometers. MINNEAPOLIS HONEYWELL REGULATOR CO. Feb. 27, 1962 [Feb. 27, 1961], No. 7706/62. Drawings to Specification. Class 97 (3). In an indicator as in Specification 903,967 for showing the temperature history of a frozen food package or other article, in which a porous medium impregnated with an electrolyte and an indicator substance, has a pair of spaced dissimilar metal electrodes, e.g. tin and copper in contact therewith to act as a galvanic cell when the temperature rises above a predetermined minimum, a complexing agent is added to the porous medium so that the metal ions generated by the less noble metal, e.g. tin ions, are bound up into a stable complex and are . unable to precipitate the hydroxyl or other ions which then give a clear indication of their migration in dependence on time and temperature. The complexing agent may be a tartrate or a citrate such as ethylenediaminetetraacetic acid. |
