sterilised in this manner.

NOTE.--Tubes, flasks, filter flasks, pipettes, glass tubing,
etc., may be rapidly sterilised, in case of emergency, by
washing, in turn, with distilled water, perchloride of
mercury solution, alcohol, and ether, draining, and finally
gently heating over a gas flame to completely drive off the
ether vapor. Chloroform or other volatile disinfectants may
be added to various fluids in order to effect the
destruction of contained bacteria, and when this has been
done, may be completely driven off from the fluid by the
application of gentle heat.

~Dry Heat.~--The _naked flame_ of the Bunsen burner is invariably used for
sterilising the platinum needles (which are heated to redness) and may
be employed for sterilising the points of forceps, or other small
instruments, cover-glasses, pipettes, etc., a very short exposure to
this heat being sufficient.

_Ether Flame._--In an emergency small instruments, needles, etc., may be
sterilised by dipping them in ether and after removal lighting the
adherent fluid and allowing it to burn off the surface of the
instruments. Repeat the process twice. It may then be safely assumed
that the apparatus so treated is sterile.

[Illustration: FIG. 25.--Muffle furnace.]

_Muffle Furnace_ (Fig. 25).--Although this form of heat is chiefly used
for the destruction of the dead bodies of small infected animals, morbid
tissues, etc., it is also employed for the sterilisation of porcelain
filter candles (_vide_ p. 42).

Filter candles are disinfected immediately after use by boiling in a
beaker of water for some fifteen or twenty minutes. This treatment,
however, leaves the dead bodies of the bacteria upon the surface and
blocking the interstices of the filter.

To destroy the organic matter and prepare the filter candle for further
use proceed as follows:

1. Roll each bougie up in a piece of asbestos cloth, secure the ends of
the cloth with a few turns of copper wire, and place inside the muffle
(a small muffle 76x88x163 mm. will hold perhaps four small filter
candles).

2. Light the gas and raise the contents of the muffle to a white heat;
maintain this temperature for five minutes.

3. Extinguish the gas, and when the muffle has become quite cold remove
the filter candles, and store them (without removing the asbestos
wrappings) in sterile metal boxes.

NOTE.--The too rapid cooling of the candles, such