The lack of rigor in the experimental design had led directly to a hasty dinner and overtime afterward.
But choosing to experiment with only a single crystal was also a precaution against potential, unknown risks. It was simply an unavoidable choice given their limited understanding.
Kraft might have regretted the time wasted, but he would have hated even more to see several samples undergo some unexpected change all at once. At least an afternoon of experiments had shown that something in the process could make it melt safely and slowly.
In the glow of the candlelight, he began another round of attempts. This time, he set a lens on the table for observation.
"This time, we'll use three portions." The professor picked out three black, salt-like grains of similar size and placed them in a glass dish. After a moment's thought, he added another. "No, let's add a control, too."
On a hunch that some later step had caused the change, he decided to start directly with liquids. He added acidic and alkaline solvents to separate samples, along with another fresh drop of blood taken from the rabbit's ear.
To minimize subjective influence and visual bias, Kraft and Kup each brought over a chair and sat at the table, watching the hourglass. They observed the samples every time they turned it over, then compared their independent conclusions.
Then came the mind-numbingly dull wait.
The hourglass took about five to ten minutes to run out—not long enough to settle into anything, but long enough to interrupt any task or entertainment that needed uninterrupted time.
Having to keep an eye on the time made it difficult to relax completely. They could only let their thoughts wander briefly nearby or pass the time with conversation.
But Kraft had never been much of a