ances, but especially with hydrogen; if chlorine comes in contact
with steam, it abstracts the hydrogen and unites with it to form
hydrochloric acid, but it leaves the oxygen free and uncombined. This
tendency of chlorine to combine with hydrogen makes it valuable as a
bleaching agent. In order to test the efficiency of chlorine as a
bleaching agent, drop a wet piece of colored gingham or calico into
the bottle of chlorine, and notice the rapid disappearance of color
from the sample. If unbleached muslin is used, the moist strip loses
its natural yellowish hue and becomes a clear, pure white. The
explanation of the bleaching power of chlorine is that the chlorine
combines with the hydrogen of the water and sets oxygen free; the
uncombined free oxygen oxidizes the coloring matter in the cloth and
destroys it.

Chlorine has no effect on dry material, as may be seen if we put dry
gingham into the jar; in this case there is no water to furnish
hydrogen for combination with the chlorine, and no oxygen to be set
free.

219. Bleaching Powder. Chlorine gas has a very injurious effect on
the human body, and hence cannot be used directly as a bleaching
agent. It attacks the mucous membrane of the nose and lungs, and
produces the effect of a severe cold or catarrh, and when inhaled,
causes death. But certain compounds of chlorine are harmless, and can
be used instead of chlorine for destroying either natural or
artificial dyes. One of these compounds, namely, chloride of lime, is
the almost universal bleaching agent of commerce. It comes in the form
of powder, which can be dissolved in water to form the bleaching
solution in which the colored fabrics are immersed. But fabrics
immersed in a bleaching powder solution do not lose their color as
would naturally be expected. The reason for this is that the chlorine
gas is not free to do its work, but is restricted by its combination
with the other substances. By experiment it has been found that the
addition to the bleaching solution of an acid, such as vinegar or
lemon juice or sulphuric acid, causes the liberation of the chlorine.
The chlorine thus set free reacts with the water and liberates oxygen;
this in turn destroys the coloring matter in the fibers, and
transforms the material into a bleached product.

The acid used to liberate the chlorine from the bleaching powder, and
the chlorine also, rot materials with which they remain in contact for
any length of time. For this rea