Edgar's patent apparatus, the "Lactogenerator," as provided by the Dairy
Supply Co., Ltd., is shown in Fig. 52.

[Illustration: FIG. 52. Edgar's "Lactogenerator"]

The milk is placed in a tinned copper-jacketed vessel and water run in
through a vertical pipe until it runs off at the overflow. Two gas
connections are required with cocks on each, the one to heat up the milk
to the boiling point and maintain it at this for thirty minutes. A
skimmer which has been placed in the milk lifts out the coagulated
protein and albumen which rise to the top. The cock is then shut and
cold water run through the jacket till the thermometer shows 90 deg. F.,
when the culture is added, and the other gas supply with the regulator
turned on, and the temperature is automatically maintained at about 90 deg.
F. Time of incubation eight to nine hours. It is recommended to turn
cold water into the jacket at the end of the period to prevent
overincubation.

A somewhat similar apparatus is that of the Willows Refrigerating Co.,
Ltd. (Fig. 53), with the exception that it has no automatic heat
regulator. It is made of tinned steel, and the operations are the same,
but the sterilising temperature (obtained by a gas ring or hot plate) is
given as 180 deg., and the incubating temperature 100 deg. to 104 deg. F.
for a period of twelve hours. Presumably this temperature is maintained
by a small gas jet or other similar source of heat. The capacity is two
gallons.

[Illustration: FIG. 53

Apparatus of the Willows Refrigerating Co., Ltd.]

In the apparatus hitherto described the milk is sterilised in bulk, and
is filled into bottles or jars after incubation, which is not a
desirable thing to do, unless the soured milk is for immediate
consumption, as there is likely to be contamination with injurious germs
from the atmosphere. In the domestic apparatus the milk is usually
incubated in covered jars in which it can be kept until required for
use, and the practice on the larger scale should be the same.

The Dairy Outfit Co., Ltd., have recognised this in their "Lacto"
apparatus (Fig. 54).

[Illustration: FIG. 54

"Lacto" Apparatus of the Dairy
Outfit Co., Ltd.]

A cylindrical vessel is set loosely on a stand, beneath which is a lamp
calculated to maintain the incubating temperature. The milk is placed in
bottles with metal screw tops, and these are put into the cylindrical
vessel; water is run in round them through the side funn