Hi from the 'tipodes, Recent posts suggest that P.C.B.s won't float on water.Is this a reasonably conclusive test ? A 1924 text which I'm reading speaks highly of zinc for multiple stationary s-gaps. Could anyone comment ( or direct me to previous posts ) ? I've been lurking in the wings for a while now, and enjoying every minute of it .Many thanks for a terrific exchange of information. Regards Neil Walker