"However, successful means have been developed for the detection
of falsehood by the study of experimental psychology. Walter, I
think you will recall the test I used once, the psychophysical
factor of the character and rapidity of the mental process known
as the association of ideas?"

I nodded acquiescence.

"Well," he resumed, "in criminal jurisprudence, I find an even
more simple and more subjective test which has been recently
devised. Professor Stoerring of Bonn has found out that feelings
of pleasure and pain produce well-defined changes in respiration.
Similar effects are produced by lying, according to the famous
Professor Benussi of Graz.

"These effects are unerring, unequivocal. The utterance of a false
statement increases respiration; of a true statement decreases.
The importance and scope of these discoveries are obvious."

Craig was figuring rapidly on a piece of paper. "This is a certain
and objective criterion," he continued as he figured, "between
truth and falsehood. Even when a clever liar endeavors to escape
detection by breathing irregularly, it is likely to fail, for
Benussi has investigated and found that voluntary changes in
respiration don't alter the result. You see, the quotient obtained
by dividing the time of inspiration by the time of expiration
gives me the result."

He looked up suddenly. "Armstrong, you are telling the truth about
some things--downright lies about others. You are a drug fiend--