1.   Before Newton, people had great difficulty understanding how any metal could conduct electricity.

2.   Some metals conduct electricity better than others.

3.   Graphite conducts electricity in the plane of the layers but not at right angles to them.

4.   For example, graphite only conducts electricity in the direction along its layers.

5.   A semiconducting material, in terms of its ability to conduct electricity, is one which lies between a conductor such as copper and an insulator such as rubber.

6.   And the rocky shell would not conduct electricity well enough to carry the current.

7.   A dielectric is a material like glass or plastic, that does not conduct electricity.

8.   A thick enough layer of dust and dirt can conduct electricity -- causing a short circuit.

9.   But a new concrete that can conduct electricity may make it possible to construct buildings in which the basic structure does double duty as an electromagnetic shield.

10.   Contact with a particular compound may or may not cause an easily measurable change in the way a given sensor conducts electricity.