"The original mineral was found on Venus, in the Gorbu-vashtar country," explained Karen Marek. "Here's a sample." She gave him a lump of rough, dense material which glittered in hard rainbow points of light. "It was just a curiosity at first, till somebody thought to test its electrical properties. Those were slightly fantastic. We have all chemical and physical data on this stuff already, of course, as well as an excellent idea of its crystal structure. It's a funny mixture of barium and titanium compounds with some rare earths and—well, read the report for yourself."

Lancaster's eyes skimmed down the sheaf of papers she handed him. "Can't make very good condensers out of this," he objected. "Too brittle—and look how the properties vary with temperature. A practical dielectric has to be stable in every way, at least over the range of conditions you intend to use it in."

She nodded.

"Of course. Anyway, the mineral is very rare on Venus, and you know how tough it is to search for anything in Gorbu-vashtar. What's important is the lead it gave Sophoulis. You see, the dielectric constant of this material isn't constant at all. It increases with applied voltage. Look at this curve here."

Lancaster whistled. "What the devil—but that's impossible! That much variability means a crystal structure which is—uh—flexible, damn it! But you've got a brittle substance here—"

According to the accepted theory of dielectricity, this couldn't be. Lancaster realized with a thumping behind his veins that the theory would have to be modified. Rather, this was an altogether different phenomenon from normal insulation.