These surround little spherules of glass which are detached when the rock is struck with a hammer.
They are due to the interposition of small spherules of water, which act the part of diffracting obstacles.
G., when formed into a charge of lead shot composed of equal spherules closely packed, will have a G.D.
Magnus showed that the stream of spherules may be diverted into another path by the attraction of a powerfully electrified rod, held a little below the place of resolution.
Small rounded spherules of iron, believed by some to be meteoric dust, have also been obtained in some numbers.