he moment Kennedy said nothing, but opened a carefully sealed door
and slid the pallet out, unhinging it, while I saw Castine trembling and
actually turning ashen about the lips.

"This," Kennedy replied at length, "is what is known as a respiration
calorimeter, which I have had constructed after the ideas of Professors
Atwater and Benedict of Wesleyan, with some improvements of my own. It
is used, as you may know, in studying food values, both by the
government and by other investigators. A man could live in that room for
ten or twelve days. My idea, however, was to make use of it for other
things than that for which it was intended."

He took a few steps over to the complicated apparatus which had so
mystified me, now at rest, as he turned a switch on opening the
carefully sealed door.

"It is what is known as a closed circuit calorimeter," he went on. "For
instance, through this tube air leaves the chamber. Here is a blower. At
this point, the water in the air is absorbed by sulphuric acid. Next the
carbon dioxide is absorbed by soda lime. Here a little oxygen is
introduced to keep the composition normal and at this point the air is
returned to the chamber."

He traced the circuit as he spoke, then paused and remarked, "Thus, you
see, it is possible to measure the carbon dioxide and the other
respiration products. As for heat, the walls are constructed so that the
gain or loss of heat in the chamber is prevented. Heat cannot escape in
any other way than that provided for carrying it off and measuring it.
Any heat is collected by this stream of water which keeps the
temperature constant and in that way we can measure any energy that is
given off. The walls are of concentric shells of copper and zinc with
two of wood, between which is 'dead air,' an effective heat insulator.
In other words," he concluded, "it is like a huge thermos bottle."

It was all very weird and fascinating. But what he could have been
doing with a dead body, I could not imagine. Was there some subtle,
unknown poison which had hitherto baffled science, but which now he was
about to reveal to us?

He seemed to be in no hurry to overcome the psychological effect his
words had on his auditors, for as he picked up and glanced at a number
of sheets of figures, he went on: "In the case of live persons, there is
a food aperture here, a little window with air locks arranged for the
passage of food and drink. That large window through which you looke