pith-ball electroscope

例句：

1. 1. The pith-ball electroscope was used to detect the presence of gases in the air.
   球状电极电测仪用于检测空气中的气体。
2. 2. The pith-ball electroscope was used to measure the electrical resistance of materials.
   球状电极电测仪用于测量材料的电阻。
3. 3. The pith-ball electroscope was used to study the properties of matter.
   球状电极电测仪用于研究物质的性质。