377 
caramel, etc. Generally speaking, the adulteration of milk with 
these artificial coloring matters is in itself of minor importance, inas- 
much as they are used in very small quantities and the coloring mat- 
ters ordinarily employed in the artificial coloring of milk have been 
found to be harmless. The fact, however, that they are employed 
mainly with a view of concealing other more dangerous adultera- 
tions, such as the addition of water to the milk, puts the addition of 
artificial coloring matters to milk in the class of dangerous adultera- 
tions. In this connection it has been pointed out by Winton (6) 
that in the examination of a foodstuff for artificial colors the chemist 
ofttimes encounters the difficulty of distinguishing a harmless from 
a poisonous color. As a rule it is an easy matter to determine when 
a synthetic color is present, but very difficult ofttimes to determine 
its precise nature. Then again, as pointed out by Tolman .(7), the 
, coal-tar colors are frequently contaminated with powerful mineral 
poisons, such as arsenic, copper, tin, lead, and zinc, which are intro- 
duced as impurities in the process of manufacture. It has been 
established further that many of the coal-tar dyestuffs are poisonous 
and that still others not very actively poisonous are still sufficiently 
toxic to interfere with the action of the digestive ferments. For 
example, Houghton (8) found that annotto diminished the digesti- 
bility of casein and egg albumen toward pepsin. For further infor- 
mation regarding the toxicity of the coal-tar dyes the following 
authors should be consulted: Weyl (9), Weber (10), # Winogradow 
(11), Gudeman (12), Chlopin (13), and Meyer (13a). 
Preservatives .-^ We have seen that milk is subject to many changes, 
principally those resulting from the life and growth of micro-organ- 
isms. Indeed it is one of the most perishable of foodstuffs, and it is 
only by exercising the most scrupulous cleanliness in the handling 
of it and by keeping it at low temperatures, generally below 50° F., 
that it can be preserved a sufficiently long time to be delivered to 
the consumer in a fresh condition. This has resulted in the practice 
on the part of the dairyman of adding to the milk small amounts of 
various antiseptics and germicides, which are supplied to the trade 
under the general name of milk preservatives. The effect of such 
substances is to destroy or at least hinder the growth of all micro- 
organisms which the milk may contain, and thereby retard the 
souring of the milk; and to prevent or at least delay the lactic-acid 
fermentation of milk is the principal object to be attained through 
the use of such substances. Among the various substances which 
have been employed as milk preservatives may he mentioned the 
following : 
Common salt, sodium bicarbonate, formaldehyde (solutions of 
which are supplied to the dairyman under the trade name of 1 1 Freez- 
ine”)> borax and boric acid (solutions of the latter once sold under 
