s as it is to
bacteria and fungi.

It can be used as a solution (one to five per cent) for the washing
of woodwork, or for the treatment of any object, since it has no
corrosive action. It can also be employed as a gaseous disinfectant
for the treatment of rooms. It is most conveniently applied by
suspending large cloths in the room and spraying them with the
solution, then closing the room for a number of hours.

=Bleaching powder.= Chloride of lime, or bleaching powder as it is
often called, is a good disinfectant, as well as a deodorant. It is
used as a wash in the proportion of four to six ounces to a gallon
of water. It must be used with care in factories since the free
chlorine that is given off has a penetrating odor.

CHAPTER VI.

PRESERVATION OF MILK.

It has been shown in a previous chapter that milk becomes
contaminated with a multitude of bacteria not only on the farm where
it is produced, but during the various stages prior to its use. Many
of the bacteria which find their way into milk are readily able to
develop, and by their growth, render the milk unfit, or even harmful
for human food. With the most stringent precautions that can
reasonably be taken, it is impossible to avoid all contamination;
hence, all grades of milk will soon spoil, unless some means of
preservation is employed. Indeed, of all the foods classed as
perishable, milk is the one that most rapidly deteriorates. Produced
under ordinary conditions, it is unfit for ordinary use in a few
hours if kept at 70 deg. F.

There are three possible ways by which milk may be preserved: (1)
The removal of bacteria that have gained entrance to it; (2) The
prevention of growth of the contained bacteria; (3) The destruction
of the contained organisms. In practice at least two and sometimes
all of these methods are employed. The prevention of contamination,
a subject discussed in Chapter III is in reality one of the most
efficient means of preserving milk. In milk production, as
elsewhere, prevention is preferable to cure. Milk produced under
such conditions that its germ content is but a few thousand per
cubic centimeter will keep much longer than that handled in the
ordinary manner.

It might naturally be supposed that any method by which dirt is
removed from milk would improve the keeping quality of milk, due to
the reduction of bacteria, yet while the straining of the milk at
the time of milking removes dirt of various kinds, it doe