A selenium cell will give much better service and have a longer life if a little care is taken with it. These suggestions if followed will prevent to a great extent irreparable damage to the cells.

Keep them cool. Do not allow them to become heated to any extent or the gold foil will combine with the selenium to form a gold selenide and destroy the sensitiveness of the cell. This condition will be indicated by dark brown splotches on the face of the cell.

Use as small current values as possible to accomplish a desired result. This demands the use of high resistance relays. Resistances may be employed in the circuit to limit the current but a high resistant relay is the proper solution.

Use the proper voltage as determined by the testing set.

Do not expose light sensitive cells to bright light for excessively long periods of time. It fatigues the cell and causes it to become insensitive temporarily.

When using generator cells do not pass a current from an outside source thru them while lighted. This destroys temporarily the generating powers of the cell.

Keep the cells dry. If not of the sealed type keep them in a box having a few lumps of calcium chloride in the bottom to absorb moisture.

When not in use they should be kept in a light tight box but should be exposed to light each day or so regardless of whether they are used or not. This aids maturing and retains the sensitiveness of the cells.

Should their resistance drop to any great extent after continued use it can again be raised by treating with an alternating or pulsating current as described under treating and testing cells.

THE END