It will be recollected that the Siamese twins, brought to England in
the year 1829, were united by a jointed cartilaginous band. A silver
tea spoon being placed on the tongue of one of the twins and a disc of
zinc on the tongue of the other, the moment the two metals were brought
into contact both the boys exclaimed, “Sour, sour;” thus proving that
the galvanic influence passed from the one to the other through the
connecting band.