Kolbe's Electrometer/Electroscope by Max Kohl (ca. 1900) |
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Standard box-like gold leaf electroscope (ca. 10" tall) for quantitative demonstrations of electrostatic phenomena and possibly the measurement of radioactive materials. Note the curved scale (mica) inside the chamber that is numbered 0 through 9. It employs a single gold leaf, a fragment of which can be seen attached to the vertical support rod. The metal components are brass that have been painted black. The four vertical sides are glass. The two sides that are not in view are covered on the inside with a metal screen to prevent static charges on the glass from affecting the movement of the gold leaf. The brass knob towards the left is used to level the electroscope and the red connector to the right is used to ground the case. The insulator appears to be quartz. In general, an electrophorus would be used to transfer a charge to the horizontal disk (Volta plate) on the top. For an explanation of how an electroscope can be charged and how an electrophorus works, click here. |
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makers name is printed on the top: Max Kohl A.G. Chemnitz. A
Max Kohl catalog from 1910-1920 lists this as "Aluminum
Electrometer (Kolbe's)." The price at the time was 3 pounds. This type of electroscope was first described by Bruno Kolbe of St. Petersburg in 1889. References Bruno Kolbe. Ein einfaches Elekrometer. Zeitschrift fur den Physikalischen und Chemischen Unterricht. April 1889;153-159. I would like to express my thanks to Jean-François Loude for providing the above reference. |
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