A. Pp. H. 4. PHENOL COEFFICIENT 167 
is placed at the right of the worker so that he can push the loop rack 
away from him and draw the inoculator toward him and when through 
inoculating reverse the action. 
Water Bath. The water bath consists of a wooden box about 18 ins. 
square and deep, containing a three- or four-gallon pail packed around 
with sawdust which is lightly oiled so as not to become dusty. The 
bath is raised from the floor about 6 ins. by cleats and castors, and when 
not in use is rolled under the bench. During the test it is on the floor 
at the right of the worker. 
Timepiece. A watch or small clock of fair accuracy, provided 
-with a second hand, is so mounted as to be conveniently and com- 
fortably read by the worker from his place at the bench. 
Culture Media, Broth. Ten grams of peptone (Witte’s), 3 gms. of 
extract of meat (Liebig’s), 5 gms. of sodium chloride, C. P. Distilled 
water 1000 c.c. Boil for fifteen minutes, make up to weight, filter tube, 
sterilize at 10 lbs. pressure for twenty minutes. No adjustment what- 
ever of the acidity should be attempted. Determine and record the 
P;, value. This should be between 6 and 7. 
Agar. To 1000 c.c. of the standard broth add 15 gms. of best grade 
agar, boil thirty minutes, make up to weight, filter and sterilize at 1 Ib. 
for twenty minutes. Do not use egg albumen to clanfy. 
Organism. For the standard test organism in determining the 
coefficient against the typhoid organism a twenty-four-hour-old broth 
culture of B. typhosus (Hopkins) 1s used. Before beginning a test the 
culture is carried over in broth at 37° every twenty-four hours for at 
least five successive days, and the last culture well shaken and filtered 
through sterile filter paper. For carrying over the culture one standard 
loop is.used. It is important that the transfers be made as nearly as 
possible as exactly on the twenty-four-hour interval, although a varia- 
tion of not more than two hours is allowable. The stock culture of B. 
typhosus (Hopkins) is kept on agar slants. These cultures are incubated 
at 37° C. for twenty-four hours and then placed in the refrigerator 
until ready for use. In no case should they be kept more than 
one month. 
Phenol. While pure phenol crystals are undoubtedly the best stand- 
ard which we have at present, they are far from being entirely satis- 
factory. Commercial phenol crystals are often contaminated with 
cresols and other phenol homologues. It is important that nothing 
but the highest grade of pure white synthetic phenol crystals be used 
of a solidifying point not less than 40° C. as determined by the method 
of Weiss and Downs. 
