the new patent were filled with water and loaded with cartridges of dry
acid and bicarbonate of soda--the cap screwed down hastily, and, as the
chemicals dissolved, the gas was generated, the pressure raised, and
the water charged by absorption. The pressure of some 80 pounds was
sufficient to project a stream 50 feet or more, and the machine was set
upon the shelf so as to be ready for any fire that might occur. In many
cases, however, the pressure escaped after a short time, and the machine
when needed was found to be useless.

The most important step in the evolution of the modern extinguisher was
the adoption of a device for mixing liquid acid with the soda solution,
by the turning of a handle or screw, _after_ the alarm was given. This
was a practical machine, and proved of such value that an immense
business was built up. The result of this prosperity was the development
of new companies with new devices for accomplishing the same result,
which were successfully offered to the public with varying success.

As these were direct infringements upon the patent rights acquired by
the Babcock Company, their encroachments were resisted in the courts,
and much money was spent in the effort of the company to sustain their
rights, including the purchase of the patents of several rival machines
that possessed real merit or whose business was worth controlling.
Among these purchases was the right and good will of the "National"
Extinguisher Co., who used an acid cartridge of glass, the acid being
liberated by breaking the glass. This feature, united with important
improvements in general construction and the use of a peculiar glass
bottle instead of a tube, is the Babcock machine of to-day, the
combination making the simplest and most effective and reliable
apparatus ever built. In the meantime, an investigation before the
courts brought out the fact that the French patent was antedated by an