i6o HOUSEHOLD BACTERIOLOGY 
MEETING IV 
(Study pages 49-62) 
Work of Bacteria 
Fermentation and putrefaction. 
References: The Story of Germ Life, by H. W. Conn. Chap¬ 
ters II III, IV. (35c., postage 6c.) 
Bacteria, Yeasts, and Molds, by H. W. Conn. 
Chapters IX-XIII. ($1.00. postage 10c ) 
Our Secret Friends and Foes, by Percy F. Frank- 
land. Chapters IV, V. ($1.25, postage 12c.) 
See also U. S. Government Bulletins. 
MEETING V 
(Study pages 63-96.) 
Harmful Dust Plants 
(a) Perform the experiments outlined on pages 64-66. 
(b) Boil a pint of milk 15 minutes. Pour into bottle 
which has been boiled in water the same time. Close 
with cork which has also been boiled. 
Pasteurize an equal portion (bottle and cork as above). 
Keep this at about 155 0 F. for 15 minutes. Keep both 
under same conditions. Test each day with blue litmus 
paper. Note first trace of acid. Test by smell and 
note first signs of coagulation. Compare results in time. 
When opening, expose as little as possible to dust. Do 
not lay cork down or touch lower part with fingers. If 
cork is handled or exposed to more dust, boil again. 
While cork is out, lay a clean wet cloth over mouth of 
bottle. 
References: Dust and Its Dangers, by T. M. Prudden. 
Chapters VI, VII, VIII. (75c., postage 6c.) 
The Story of Germ Life, by H. W. Conn. Chapters 
V, VI. (35c., postage 6c.) 
