eady stated, it
is a common thing for the dairyman to add a small quantity of anatto or
an aniline dye of a similar shade, to give the milk a rich creamy tint.
If the milk is of a reddish colour this may be caused by blood from the
udder, although certain foods, such as beets, mangels, and carrots
sometimes give a similar tint. The milk given by cows immediately after
calving is called "colostrum" or "biestings," and is of a yellow or
yellow-brown colour. It is much thicker than ordinary milk, and
coagulates in boiling.

In dirty byres in which care is not taken in milking, quite considerable
quantities of hairs, pieces of manure, and other filth may get into the
milk. Usually the milk is strained by the dairyman, but sometimes this
is omitted or carelessly done. To test for dirt, a ribbed glass funnel
is useful. Get a piece of the finest muslin about twice the diameter of
the funnel, fold over twice, so that it becomes one quarter of its
original size; open one of the sections and place in the funnel; pass
the milk into this. It will run through quickly and some water may be
run into the funnel to clear away the last traces of milk. The filter
cloth can then be opened out and any dirt retained will become visible.
The apparatus is shown in Fig. 6.

[Illustration: TESTING-GLASS FOR EXTRANEOUS MATTER IN
MILK.

FIG. 6.--A piece of muslin is folded as shown and a
measured quantity of milk is passed through the funnel;
from the sediment left in the muslin, the percentage of
extraneous matter may be arrived at.]

If a glass funnel is not available, a very small jelly bag can be made
of fine gauze and used in the same way. The washing water should be used
in small quantities and directed to concentrating the dirt in the apex
of the bag. After washing, the latter can be turned outside in, to
permit of readier examination of the dirt. The bag should be well
washed in cold water, then boiled and dried, and is then ready for
future use.

The acidity of milk is a very useful guide to its age. Milk has the
curious property of being "amphoteric," _i.e._, it is both slightly acid
and slightly alkaline when fresh. As its age increases, however, so does
its acidity, and at a rate varying with the temperature and moisture
contents of the atmosphere in which it is placed. Old and acid milk is
heavily contaminated with bacteria, a proportion of which are likely to
be injurious to health.

[Illustration: FIG. 7. Lact