CANNOT BE FILTERED OUT 19 
BACTERIA CANNOT BE FILTERED OUT 
Dirt and bacteria travel together. Because the 
strainer removes dirt, some think it removes 
bacteria. The fact is that the finest strainer 
used by dairymen removes only the very coarse 
dirt, and leaves still in the milk all of the fine 
dirt. Bacteria are much smaller than even the 
finest dirt, and easily pass through the strainer 
with the milk. 
The cheese cloth or wire commonly used for 
straining is 32 meshes to the inch. The finest 
cheese cloth that can be purchased has 64 meshes 
to the inch. Under a magnifying glass the meshes 
of fine cheese cloth appear very large. Since 
it takes 25,000 bacteria to cover 1 inch in length, 
400 bacteria could be placed in a row in the 
space between two threads of the finest cheese 
cloth, and through one of the square openings 
of such a cloth a regiment of 160,000 bacteria 
could march abreast. 
Bacteria are much smaller than the drops of 
butter fat in milk, therefore a strainer fine enough 
to remove bacteria would also remove all of the 
butter fat, and allow only skim-milk to pass 
through. 
