6 HOUSEHOLD BACTERIOLOGY. 



What did you find on your return ? A slimy film ovei 

 the surface of the water, did you not? 



Such experiences may be familiar to all. A few 

 years ago these changes were thought to be due to the 

 oxygen of the air, which in some way, under certain 

 conditions, made some things sour, some bitter, and 

 others putrid. 



^ n ^ e ^ a y s ^ our g Tan d r nothers much of the 

 bread was made with leaven like that used in Bible 

 times a mixture of flour and water exposed to the 

 air and whatever the air contained. This, was called 

 "barm." Such bread is still common in some parts 

 of our country, and known as "salt-rising bread," 

 and the barm when made with milk is called "milk 

 emptins." 



In the old days a portion of the leavened mass 

 was kept to start the next batch of bread. Occa- 

 sionally this was forgotten or it spoiled, then the 

 housewife borrowed from her neighbor, as when the 

 fire on the hearth was out, a coal was borrowed. 

 Sometimes now the yeast raised sponge becomes slight- 

 ly sour before it is ready for baking. Why ? 



Apple or other sauces containing sugar ferment 

 or sour and the housewife scalds them. This may 

 make them as palatable as when freshly stewed. Yet 

 they often turn sour again and, after a while, scalding 

 or even boiling does not remove the sharp or sting- 

 ing effect upon the tongue. 



MOW The moist bread in the jar is found specked with 

 mold ; some August morning the sprinkled clothes 



