Chap. XXI .
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If Paper or any other Medium be interposed, an armed loadstone raises no more than an unarmed one .
O bservation has shown above that an armed loadstone does not attract at a greater distance than an unarmed one; yet raises iron in greater quantity, if it is joined to and made continuous with the iron. But if Paper be placed between, that intimate cohæsion of the metal is hindered, nor are the metals cemented together at the same time by the operation of the magnet.