On a new method of detecting pyro-electricity

Abstract

Introduction—pyro-electricity has been investigated by various methods. Sir David Brewster heated his crystals and brought them into contact with small, very light, insulating particles: If these adhered, the presence of pyro-electricity in the crystal was inferred. He also used a very delicately suspended brass needle. Being a conductor it was attracted to a charged crystal when this was brought near to it. Hankel placed the crystal under investigation in a small bath of copper or iron filings, which was then put into a hotair oven. The filings did not entirely cover the whole crystal, but one corner, edge, or face, whichever was required, was left exposed. A very small platinum sphere connected to an electrometer was then brought near to the exposed portion. The charge induced on the sphere was taken as a measure of the charge developed at the particular spot on the crystal opposite the platinum sphere.