CONTROL OF CITY MILK SUPPLY G37 
that milk be sold as it comes from the cow; that is, it 
would be illegal to remove a part of the fat from milk, 
even if this would leave it above the minimum composi- 
tion fixed by law. 
The matter of detecting watering and skimming is 
discussed in chapter VIII. 
Preservatives and Dirt. Preservatives are often 
found in market milk. Those most commonly used are, 
boracic acid, formalin, salicylic acid and carbonate of 
soda. The use of these preservatives materially prolongs 
the keeping quality of the milk owing to their antiseptic 
properties. Every effort should be made, however, to 
inflict maximum punishment upon users of preservatives 
because their poisonous nature makes them very detri- 
mental to health. 
So far as dirt is concerned, it cannot technically be 
classed as a milk adulterant, though in its effects it may 
be fully as detrimental to health as preservatives. 
The presence of dirt in milk presupposes the presence 
of an undue number of dirt-loving bacteria which, at 
least so far as babies and young children are concerned, 
are perhaps just as detrimental to health as preservatives. 
Filthy milk has killed thousands of children under two 
years of age, and its use should be strictly prohibited. 
The methods of determining preservatives and dirt in 
milk are discussed in Chapter XXV. 
Bad Fermentations. It has already been stated that 
the number of bacteria in any given sample of milk is 
of less consequence than the class to which they belong. 
Filthy milk, if promptly and thoroughly cooled, may 
come within the numerical limit established for bacteria 
by any particular city, yet such milk may be extremely 
