“Well, it’s like this,” said Waters. “When the planet cooled, the molecules of that original inorganic planetary matter were symmetric—if crystallised, the crystals were symmetric also. That is, they were alike on both sides, like a geometrical cube, and their reversed or mirror-images would be identical with themselves. Substances of this kind are said to be optically inactive; that is to say, if viewed through the polariscope, they have no power to rotate the beam of polarised light.”
“We will take your word for it,” said Perry.
“Oh, well, that’s quite simple. Ordinarily speaking, the vibrations in the aether—need I explain aether?”
“I wish you could,” said Hoskyns.
“We will pass aether,” said Perry.
“Thank you. Well, ordinarily the aetheric vibrations which propagate the light takes place in all directions at right angles to the path of the ray. If you pass the ray through a crystal of Iceland spar, these vibrations are all brought into one plane, like a flat ribbon. That is what is called a beam of polarised light. Very well, then. If you pass this polarised light through a substance whose molecular structure is symmetric, nothing happens to it; the substance is optically inactive. But if you pass it through, say, a solution of cane sugar, the beam of polarised light will be twisted, and you will get a spiral effect, like twisting a strip of paper either to the right or to the left. The cane sugar is optically active. And why? Because its molecular structure is asymmetric. The crystals of sugar are not fully developed. There is an irregularity on one side, and the crystal and its mirror image are reversed, like my right hand and my left.” He laid the palm of the right hand on the back of the left to show his meaning. We all frowned and practised on our own hands.
“Very good,” continued Waters. “Now, we can produce in the laboratory, by synthesis from inorganic substances, other substances which were at