DISEASE GERMS 
85 
must be capable of and receive complete sterilization. 
Any faucet filter which allows a generous stream of 
water to issue quickly after it is turned on is practical¬ 
ly useless so far as the removal of bacteria is con¬ 
cerned. 
A suspected water or one of unknown quality would Filter 
better be filtered and then boiled rather than boiled ajid Boif 
filtered, if it needs to be filtered to remove suspended 
matter. Distilled water or water turned into steam 
and condensed is a pure water; but to remain so it 
must be received into perfectly clean vessels and not 
exposed to dust. 
Ice as ordinarily delivered frequently shows three Ice 
layers. One, usually at the top, the snow ice, is scarce¬ 
ly transparent and when melted shows impurities not 
visible in the ice. This usually holds many bacteria 
and should always be rejected. Another layer, par¬ 
tially transparent, is more or less bubbly. These 
bubbles contain air which allows any living forms 
therein to remain alive if not to grow. If derived 
from impure water the bubbles may contain some 
of the germs which will make the ice undesirable, 
since many bacteria survive a lower temperature than 
ice ever attains. A third portion is wholly trans¬ 
parent. This last, the crystal clear ice, is the only ice 
which should ever be used directly to cool drinking 
water, for this alone is purified by crystallization al¬ 
though not perfectly. 
Ice should always be washed from surface dirt before 
