Then he let the toad go and remained sitting for a long time with the copper-wire and the zinc-wire in his hand and gazed before him, plunged in thought. Then he said:
“Come, let us go in.”
“Yes, it’s time for bed,” said the disciple. “It’s quite dark.”
“It’s time for work,” said Two-Legs. “To-night a light has been kindled for me, brighter than any before.”
He told the disciple what he had noticed and explained his thought to him:
“It was the electric spirit,” he said. “I think it was the toad’s moist skin that made him show himself. Now we will experiment with copper and zinc.”
He took a glass and filled if half with water and put into it a small piece of zinc and a small piece of copper. Then he fastened a slender wire to the zinc, let the wire stand up in a wide curve and fastened the other end to the copper:
“What shall we put into the water?” he said. “There is sulphur and there is lime and there are a thousand things, in the toad’s skin.... The question is how to hit upon just the right one.”
He experimented patiently. When he put a piece of sulphur into the water, it began to bubble round the zinc.