"_Puratylene,_" a mixture of bleaching powder and hydroxide of lime,
made very porous, and containing from eighteen to twenty per cent of active
chlorine.

"_Frankoline,_" a mixture of cuprous and ferric chlorides dissolved in
strong hydrochloric acid absorbed in infusorial earth.

A test for impure acetylene gas is made by placing a drop of ten per cent
solution of silver nitrate on a white blotter and holding the paper in a
stream of gas coming from the torch tip. Blackening of the paper in a short
length of time indicates impurities.

_Acetylene in Tanks._--Acetylene is soluble in water to a very limited
extent, too limited to be of practical use. There is only one liquid that
possesses sufficient power of containing acetylene in solution to be of
commercial value, this being the liquid acetone. Acetone is produced in
various ways, oftentimes from the distillation of wood. It is a
transparent, colorless liquid that flows with ease. It boils at 133
Fahrenheit, is inflammable and burns with a luminous flame. It has a
peculiar but rather agreeable odor.

Acetone dissolves twenty-four times its own bulk of acetylene at ordinary
atmospheric pressure. If this pressure is increased to two atmospheres,
14.7 pounds above ordinary pressure, it will dissolve just twice as much of
the gas and for each atmosphere that the pressure is increased it will
dissolve as much more.

If acetylene be compressed above fifteen pounds per square inch at ordinary
temperature without first being dissolved in acetone a danger is present of
self-ignition. This danger, while practically nothing at fifteen pounds,