er consists of a glass tube containing a chemical with a strong
odor; the tube is fitted with a glass cover, held in place by a string
and a paper band. When the tester is thrown into the pipes and hot
water poured after it, the paper band breaks, the spring opens the
cover, and the contents of the tube fall into the drain.

Recently Dr. W. G. Hudson, an inspector in the Department of Health of
New York, has invented a very ingenious "peppermint cartridge" for
testing plumbing. The invention is, however, not yet manufactured, and
is not on the market.

CHAPTER X

=Infection and Disinfection=

Disinfection is the destruction of the infective power of infectious
material; or, in other words, disinfection is the destruction of the
agents of infection.

An infectious material is one contaminated with germs of infection.

The germs of infection are organic microoerganisms, vegetable and
animal--protozoa and bacteria.

The germs of infection once being lodged within the body cause certain
reactions producing specific pathological changes and a variety of
groups of symptoms which we know by the specific names of infectious
diseases, e. g., typhoid, typhus, etc.

Among the infectious diseases known to be due to specific germs are
the following: typhoid, typhus, relapsing fevers, cholera, diphtheria,
croup, tuberculosis, pneumonia, malaria, yellow fever, erysipelas,
_septicaemia_, anthrax, _tetanus_, gonorrhea, etc.; and among the
infectious diseases the germs of which have not as yet been discovered
are the following: scarlet fever, measles, smallpox, syphilis,
varicella, etc.

The part of the body and the organs in which the germs first find
their entrance, or which they specifically attack, vary with each
disease; thus, the mucous membranes, skin, internal organs,
secretions, and excretions are, severally, either portals of infection
or the places where the infection shows itself the most.

The agents carrying the germs of infection from one person to the
other may be the infected persons themselves, or anything which has
come in contact with their bodies and its secretions and excretions;
thus, the air, room, furniture, vessels, clothing, food and drink,
also insects and vermin, may all be carriers of infection.

=Sterilization= is the absolute destruction of _all_ organic life,
whether infectious or not; it is therefore _more_ than disinfection,
which destroys the germs of infection alone.

A =Disinf