Sentence:Formerly it was usual to insulate the [e1]rod[/e1] of the [e2]electroscope[/e2] by passing it through a hole in a cork or mass of sulphur fixed in the top of the glass vessel within which the gold leaves were suspended.
 e1: rod. 
 e2 : electroscope.
Answer: Component-Whole(e1,e2)