“I remember. Yes. The band of light will be rotated as it passes through.”
“That’s right. It will come round into line with the foliations of the analyser, and—”
“Come through!” said I, triumphantly.
“Thank God for a man of intelligent mind. As you rightly say, it will come through. And therefore you will see—”
“Light!” said I.
(Pom, pomty; pom, pomty—if I could have got rid of that relentless drumbeat. My heart seemed to be going very heavily too.)
“But if,” went on Waters, with his eye on Sir James, who was stirring his solutions with a glass rod over the sink, “if the substance should be optically inactive—if, for example, it should turn out to be a synthetic product, prepared from inorganic substances in the laboratory—then it will not rotate the beam of polarised light. The darkness will persist.”
I saw that.
“Well, now you perfectly understand. If, when we put the muscarine solution in the polariscope, we get light, it proves nothing. Either the stuff is natural, or else the synthetic preparation has already been split up into its two active forms, and we can make no pronouncement about it. But if we get darkness—then it’s a pretty dark business, Mr. Munting.”
I nodded.
“Well, Waters,” said Sir James, cheerfully, “finished your lecture?”
“Quite. The pupil is highly commended.”
“Good. Now, I’m in your hands, Waters. What do you want me to do?”