A soap-bubble as it floats in the light of the sun reflects to the eye
an endless variety of the most gorgeous tints of colour. Newton
shewed, that to each of these tints corresponds a certain thickness of
the substance forming the bubble; in fact, he shewed, in general, that
all transparent substances, when reduced to a certain degree of
tenuity, would reflect these colours. Near the highest point of the
bubble, just before it bursts, is always observed a spot which
reflects no colour and appears black. Newton shewed that the thickness
of the bubble at this black point was the 2,500,000th part of an inch!
Now, as the bubble at this point possesses the properties of water as
essentially as does the Atlantic Ocean, it follows that the ultimate
molecules forming water must have less dimensions than this
thickness.--_Lardner's Handbook._