4 General Bacteriology. 
be so arranged that a temperature of 150° C. can be quickly reached and readily main- 
tained. In such a sterilizer all glassware to be used for the reception of culture media, 
such as flasks, test-tubes, Petri dishes, etc., is submitted to a temperature of 140-150° C. 
for 1 hour, or until the cotton plugs are slightly browned; this change being due to the 
incipient charring of the cotton. The test-tubes are placed erect in square baskets made 
of galvanized iron wire. When the air in the sterilizer has cooled to about 40° C. the 
glassware can be taken out and stored ready for use. The Petri dishes are not to be opened 
until used for culture purposes. 
Rererences. A. 71 and 121; H. 32; L. & K. 74; M. & R. 36; N. 159; McF. 
106; P. 228; S. 51. 
SpectaL Directions. Ail glassware prepared in I. is to be sterilized for one 
hour at 150° C. The small pipettes should be placed in brass tubes, provided for the 
purpose, and also sterilized. 
EXERCISE IV. PREPARATION OF BOUILLON. 
GENERAL Directions. Any one of the three methods (A B or C) may be used. 
They are arranged in order of preference, but method C is the most convenient, and 
hence most used. 
A. 
a. From 500 grams (14 Ib.) of lean 
beef, remove the fat and connective tis- . 
sue and mince (Hamburg steak). 
b. Add 1 liter of distilled water and 
after thoroughly shaking set in ice chest 
for 12 to 24 hours. : 
c. Squeeze through a cloth and add 
enough distilled water to make 1 liter 
and place in vessel to cook. This may be 
done either in a flask which is heated ina 
water-bath or a sterilizer, or in a rice 
cooker. In this case use 250% solution of 
calcium chloride in outer vessel instead 
of water as by this means the contents 
of the inner vessel can be brought to a 
rapid ebullition, something impossible by 
the use of water alone. 
d. Boil + hour and make up loss of 
water. 
e. Add to any of the above solutions: 
B. 
Secure meat as 
under A a, add 1 liter 
of distilled water, 
weigh (see e below), 
cook for } hour at 
about 70° C., and pro- 
ceed as directed under 
e below. 
Cc. 
Weigh out three 
grams of beef extract 
(such as Liebig’s), 
add 1 liter of water, 
and then proceed as 
directed under e be- 
low. 
1% (10 gms.) peptone (Witte) and +% (5 gms.) common salt (NaCl), then weigh 
solution, with vessel, so that the water which is subsequently driven off in cooking can 
be accurately replaced. 
f. Heat until ingredients are in solution, then restore the water lost by evaporation. 
g. Neutralize or render slightly alkaline. 
great care. 
work. For ordinary routine work B may be employed. 
This is a very important step and calls for 
Method A is more accurate and should be employed for special or research 
