el, the vessel
lifted off the stand, and heated to sterilising point on a stove. Cold
water is then run in through the funnel until the temperature is low
enough for incubation. Culture is added to each bottle and the lids
screwed on, the vessel lifted on to its stand, and the lamp lighted. The
cover of the apparatus has a thermometer fixed on it.

On the large scale the treatment of the milk would take place entirely
in the jars in which it would be sent out, and the sterilisation and
incubation would be conducted in different pieces of apparatus. The
sterilisation would be effected either (1) by direct steaming, or (2) by
hot water heated by steam. Fig. 55 shows the first type of
sterilisation. The tank is of wrought iron or steel with strengthening
pieces of angle iron. The door, with pulleys and counterweight for easy
handling, is fastened steam-tight by hinged bolts. The apparatus is
mounted on a stand at a convenient height for handling the bottles; and
in front is another stand with channel iron rails to take the waggon in
which the bottles or jars to be sterilised are packed. When the door is
fast, steam is turned on, and regulated to produce the proper
temperature by the thermometer fixed in the shell, in which a pressure
gauge is also secured. After sterilising, the door is opened and the
waggon drawn forward to the outside, allowed to cool, or removed
elsewhere to cool, and allow space for a new charge.

[Illustration: FIG. 55.--Sterilising Apparatus for
sterilising milk on the large scale. The bottles of milk
are sterilised, and the culture can then be added, and the
incubation allowed to proceed in an insulated chamber.]

The second method of sterilising is by hot water, as in Fig. 56. The
bottles or jars are placed on a perforated false bottom in the
rectangular tank, water run in up to the necks, and steam turned on; the
lid is fastened with hinged and hooked bolts; a thermometer fastened in
the lid, and with a long stem enclosed in metal, indicates the
temperature. At the end of the sterilising process cold water is turned
on, and at the same time the overflow water cock is opened; the cold
water gradually reduces the temperature, and the incubating point is
quickly reached.

[Illustration: FIG. 56 Another Method of Sterilising
(Dairy Supply Co., Ltd.).]

Incubation in bottles or jars, sterilised in these ways, can best be
conducted in an insulated room, with say, six inches of silicate