52 PREPARATION OF CULTURE-MEDIA. 
9. Heat over boiling water (or steam) bath thirty 
minutes. 
10. Restore weight lost by evaporation to origi- 
nal weight of filtered meat-infusion, for bouillon 
and gelatin, and to éwce that weight for agar— 
1800 grams in each case. 
11. Titrate, reaction probably + 0.3 to + 0.5 per 
cent. 
12. Adjust reaction to final point desired, + 1.5 
per cent. 
9... Graniteware funnel. 
f---. Layer of absorbent 
cotton. 
Seserananstebenseceecelier Coil of wire to pre- 
vent cotton from 
entering tube of 
funnel 
Fic. 27.—Filter for culture-media. 
13. Boil five minutes over free flame, with stir- 
ring. 
14. Add water if necessary to make up loss by 
evaporation to 1800 grams. 
15. Filter through absorbent cotton, passing 
the filtrate through the filter repeatedly until 
clear. 
16. Titrate to determine whether or not the de- 
sired reaction has been maintained. 
