Carbon dioxide is an innocuous gas; water charged with it squirts from soda-fountain nozzles to make the fizz in sodas.
As "dry ice" it is used to keep things cold.
Last week carbon dioxide, liquefied, solidified and then crushed, was used in Denver to propel bullets from guns.
Inventor Ray J. Monner thought he had something. Colorado's Home Guard thought so, too; it ordered a hundred of Monner's cartridge-less dry-ice guns to replace the regulation rifles taken over by the Army.
Monner confines crushed dry ice in a special chamber of the gun. There it...