214 



FIEST YEAR SCIENCE 



preserves it ; that salt acts as a preservative ; that if fruit 

 is heated to a boiling temperature and tightly sealed in 

 cans it will keep, and that fruits do not spoil if placed in 

 strong sugar sirups. 



These and many other methods are used to keep bacteria 

 away from food and to prepare the food in such a way that 

 bacteria cannot live in it. It is found that bacteria do not 



PREPARING SMOKED FISH AT GLOUCESTER. 



thrive as well if placed where it is cold, so foods are kept 

 in cold places. Many bacteria cannot stand the sunlight; 

 that is one of the reasons why it is so much more healthful 

 to live in sunny rooms. 



Steam is sufficient to kill bacteria as they usually 

 exist. Under some conditions they can, however,- with- 

 stand a greater temperature than that required to boil 

 water. We found that they did not pass through ab- 



