At the moment, her class was either looking at her or their open books, and all of them were fidgeting. They wound their legs around the metal supports of the seats in front of them, sliding down farther and farther in their chairs and doodling aimlessly with their pens. Lisa Hamilton talked on, and she was only half-heard, the teenagers impatient to get outside in the lovely weather, their eyes rolling around the room like cattle in a small enclosure.

Finally the voluptuous blonde teacher made a complete circuit of her class and came once more to her desk. It was on a raised platform and was much larger than any of the others, and was cluttered with reports and bunsen burners and all the paraphernalia necessary to conduct experiments. When she stood behind her desk and stared out at them, the students all knew it was time to pay closer attention, as much as they wished not to, and there was the soft sibilant sound of cleared throats and shifting clothes, like the rustle of dry leaves across the ground.

"Bertram," she said, indicating a tow-headed boy. "Would you tell us all what happens when acids are added to bases?"

"Uh… salts are formed, Mrs. Hamilton."

"Very good. And what determines the number of salts which can be formed? Not you, Elmira, I can see you've done your homework! Sherry? Will you tell the class the answer?"

The girl in the third row, fourth seat blushed a violent red, and lowered her head. "It… it is determined by… by… by…"

"Don't you know, Sherry?"

"Yes, Ma'am… only I can't say it."

Lisa Hamilton made a mark in her grade book with an indelible pencil. "Then I'll say it for you, Sherry. A salt is formed by the replacement of the atom or atoms of hydrogen in the acid by the metallic atoms of the base. Thus acids which contain more than one atom of hydrogen can have more than one salt. How many salts can sulfuric acid have, ah… Jerrold?"