areful attention.

For the keeping of soured milk, a cold room cooled by a refrigerating
machine would be desirable, so as to maintain the fermented milk at a
low temperature and prevent over-fermentation.

Apparatus has been designed so as to handle soured milk on a large
scale, and one of the machines is shown on the illustration (see Fig.
9). It is simply a jacketed cylinder with a cover and an agitating gear.
The inside of the machine is nickel-plated, and there is an arrangement
whereby the cooling may be done rapidly, through a coil inside the
jacket, this coil being connected to the brine circulation of the
refrigerating machine.

[Illustration: CONTINUOUS APPARATUS FOR THE PRODUCTION OF
LARGE QUANTITIES OF SOURED MILK

FIG. 9--This apparatus is made by the Dairy Machinery and
Construction Company of Shelton, Conn., U S A. The milk is
agitated inside a jacketed cylinder, where it is allowed
to incubate at about blood heat. The milk can be rapidly
heated and also rapidly cooled by means of this
apparatus.]

The machine is filled with milk containing three per cent. of fat, which
has been previously pasteurised to about 190 deg. F., and cooled down to
about 90 deg. F.; at this point the pure culture of _Bacillus bulgaricus_
is introduced, and the agitator is kept working, so as to mingle it
thoroughly with the milk. The agitator is then stopped until the acidity
shows a test of 0.9 to 1.0 per cent., when the agitator is again
started, and cold brine from the refrigerating machine is turned on to
the cooling pipes, so that the product is thoroughly broken up, and
cooled down to 40 deg. F.

The milk is then transferred to a bottle-filling machine (Fig. 10),
poured into bottles and hermetically sealed, after which it is ready for
consumption. When it has to be kept for any time it should be placed
in a cold room where there is a temperature not higher than 40 deg. F.

The process, therefore, is a simple one, and lends itself to the
ordinary dairy business, without involving any great expenditure on
account of a new plant.

CHAPTER V

THE BACTERIOLOGY OF FERMENTED OR SOURED MILK

A CHAPTER FOR STUDENTS

During the last few years much work has been done in investigating the
action of various classes of organisms--bacteria, yeasts, and
moulds--upon milk and its products. While, however, the attention of the
dairyman has been chiefly directed to the propagation of acid-producing
org