He improved and followed from the works of Luigi Galvani, which used a 'frog galvanoscope' as a prototype of measuring current. He recognized that a compass could actually measure current, given that it is placed near coil of wire.
Answer:
Things like salt, sugar and coffee dissolve in water. They are soluble. They usually dissolve faster and better in warm or hot water. Pepper and sand are insoluble, they will not dissolve even in hot water.
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