I sat up. "What have found out from my notes? Don't deceive yourself, father."
He laughed uproariously. "Thanks for the advice. But, Ted, I'm an old newspaper man, and I spent a good many years finding out things I was not supposed to know about. When I went over your notes I observed something I think you have missed."
My face burned. If true, of course it meant I was a damned incompetent person to trust with a responsible job. I felt Helen's hand on my knee.
"It isn't your fault, Ted—don't look so melodramatic. Now listen to me. You have tested and analyzed all your raw materials—and have bought different lots of them from various sources?"
"Yes—I have been all over the market for them."
"But you have bought your most important reagent—a commercial acid—from only one particular firm. Did you analyze that acid?"
"No."
"I thought not. There was no record of it in your books."
The sensation of feeling an utter fool is not comfortable. It was the even pressure of Helen's hand on my knee that kept me from an outburst. The instant my father had asked me the question about the acid, I knew he had found the only untested link. But why in the name of all that is intelligent had I missed it? Simply because I had been working on the set idea that the raw materials furnished contained somewhere an impurity, and I had taken the reagent on faith.
"Well," my father called out gaily, "is the old man right?"