Thimble battery

The similar chemical effects of frictional and voltaic electricity led him to conclude that they were identical, long before such a view became commonplace. Later, after perfecting the process of drawing extremely fine platinum wires, Wollaston constructed his "thimble battery", which was a very small galvanic cell capable of bringing a platinum filament to incandescence upon iimiersion in dilute vitriolic acid. Both demonstrations illustrate Wollaston s talent for eadiibiting natural phenomena by means of inexpensive "shirt-pocket" devices. 

A combination glass, silver-silver chloride reference electrode was used for pH measurement, a platinum thimble electrode and silver-silver chloride reference electrode for Eh measurement. Eh and pH measurements were made with a Coleman Medallion Model 37 battery- or line-operated pH-millivolt meter and/or a Coming 12 Research pH-millivolt meter. The pH measurements were calibrated with nominal pH 4 and 7 buffers. Double buffer checks were within 0.02 pH unit. Eh measurements were calibrated with Zobell solution [0.0003M K3Fe(CN )c, 0.0003M K4Fe(CN)c 3H20, and 0.1M KC1]. From 0° to 25°C, the Eh of Zobell solution obeys the equation... 

Zirconia solid electrolyte sensor element is formed in thimble shape. Pt electrode layers as a thin film are adhered inside and outside of the sensor element by plating method. The portion of the sensor element is shown in Figure 3.1.1. The partially stabilized zirconia solid electrolyte sensor element is assumed as one wall. Along the border of the wall, oxygen in ionic form is transferred in a direction that reduces the difference of oxygen partial pressure between chamber A and chamber B. The series construction works as a battery due to the transfer. 

The device. Figure 2, consisted of a plate of zinc nearly one inch square mounted inside a topless, flattened copper thimble by sealing wauc. Attached to the metals of the battery were two closely spaced, parallel platinum wires, between which ran a very short length of extremely fine platinum wire about 1/3000 of an inch in diameter. When lowered into a dilute solution of sulphuric acid, the current generated is sufficient to heat the fine platinum wire to incandescence. Of the working of this remarkable little device, Wollaston only says... 

---