When mine water is acid the working parts of the pump must be lined with or made of bronze or other non-corrosive material; or the acid may be neutralized by adding lime in the sump.
The working parts of the plough are the coulter, the share, and the breast or mould-board.
The chief working parts are shown in fig.
For such purposes the whole of the working parts are contained in a metal case; the indicating needle moving over a divided scale which is calibrated to show directly the potential difference in volts of the terminals of the instrument.
All the working parts of the instrument were supported on the base, so that on removing a glass shade which serves as a Leyden jar they can be got at and adjusted in position.