STERILIZATION AND DISINFECTION. 141 
to withstand the pressure of four or five atmospheres. It is fitted with 
a safety valve, which may be set to blow off at any desired pressure. 
Describe the apparatus used in generating dry heat. 
It is a simple, double-walled box of sheet iron or copper. Aper- 
tures are made for the entrance and exit of air between the double 
walls, the heat to be utilized entering from the bottom. 
What form of apparatus is used for discontinuous sterilization ? 
This apparatus consists of a chamber fitted with a cover and covered 
with a non-conducting jacket or an extra wall of metal, so that the 
steam may not be cooled by contact with outside air. The ‘“ Arnold” 
steam sterilizer is well adapted for this work. The steam is generated 
in the lower portion of the vessel and rises into the sterilizing chamber 
through a hollow cylinder. It is so constructed that the water of con- 
densation from the steam is used repeatedly. It therefore requires but 
little attention. 
What is disinfection as differentiated from sterilization ? 
It is a destruction of bacteria by the chemical action exerted upon 
them by certain substances which probably enter into combination 
with the protoplasmic constituents of these organisms. 
In order that a disinfectant may act, what is absolutely necessary ? 
The disinfectant must be brought into direct contact with the organ- 
ism to be destroyed in order that chemical action may take place. The 
idea generally prevalent among the laity, that infectious bacteria may 
be destroyed in apartments by permeating said apartments with dis- 
agreeable odors is erroneous. 
Name some of the chemical agents that are the most reliable as 
infectants. 
Carbolic acid, chlorine preparations, bromine, creolin, sulphurous 
acid and corrosive sublimate in solution. This latter chemical is the 
most powerful of all known chemical disinfectants. 
What is an antiseptic ? 
It is a substance that by its presence inhibits the growth and de- 
velopment of bacteria without necessarily killing them. 
What is the most effective of all disinfectants ? 
Fire. Corrosive sublimate might be placed first on the list of chem- 
ical disinfectants, but if much albuminous material were present, its 
action might be neutralized by combining with the albumen. 
