There was a question (from Larkin?) on non-electronic time delay
>components, and I recalled such a thing from the 1970s, when I
>considered using it to sequence an electromechanical gadget. Turned
>out to bet too complicated in that application, and went to a CMOS >counter.
>
>Anyway, the name came to me today, and it is still made.
>
>Curtis coulometers are analog Elapsed Time Indicators (ETIs) which use
>an electro-chemical plating process to integrate current over time. >
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>This uses mercury, but if I recall correctly, the 1970s original used
>silver. I think it was called a coulcell. The original company seems >to be gone.
>
>Joe Gwinn
The first residential electric meters, in the Edison DC days, were electrochemical. I think they weighed something to set the bill.