As already suggested, the walls are constructed of the largest possible
sheets of copper with a minimum number of seams and opportunities for
leakage. In testing the apparatus for leaks, the greatest precaution is
taken. A small air-pressure is applied and the variations in height of a
delicate manometer noted. In cases of apparent leakage, all possible
sources of leak are gone over with soapsuds when there is a slight
pressure on the chamber. As a last resort, which has ultimately proven
to be the best method of testing, an assistant goes inside of the
chamber, it is then hermetically sealed, and a slight diminished
pressure is produced. Ether is then poured about the walls of the
chamber and the odor of ether soon becomes apparent inside of the
chamber if there is a leakage. Many leaks that could not be found by
soapsuds can be readily detected by this method.