DAIRY MACHINERY
MILKING MACHINES--CREAM SEPARATORS--A MACHINE FOR DRYING MILK
MILKING MACHINES
The farm labourer, perched on a three-legged stool, his head leaning
against the soft flank of a cow as he squirts the milk in snowy jets
into the frothing pail, is, like the blacksmith's forge throwing out
its fiery spark-shower, one of those sights which from childhood up
exercise a mild fascination over the onlooker. Possibly he or she may
be an interested person in more senses than one, if the contents of the
pail are ultimately to provide a refreshing drink, for milk never looks
so tempting as when it carries its natural froth.
Modern methods of dairying demand the most scrupulous cleanliness in
all processes. Pails, pans, and "churns" should be scoured until their
shining surfaces suggest that on them the tiniest microbe could not
find a footing. Buildings must be well aired, scrubbed, and treated
occasionally with disinfectants. Even then danger may lurk unseen, and
the milk is therefore for certain purposes sterilised by heating it to
a temperature approaching boiling-point and simultaneously agitating it
mechanically to prevent the formation of a scum on the surface. It is
then poured into sealed bottles which bid defiance to exterior noxious
germs.
The human hand, even if washed frequently, is a difficult thing to keep
scientifically clean. The milkman has to put his hand now on the cow's
side, now on his stool; in short, he is constantly touching surfaces
which cannot be guaranteed germless. He may, therefore, infect the
teats, which in turn infect the milk. So that, for health's sake as
well as to minimise the labour and expense of milking, various devices
have been tried for mechanically extracting the fluid from the udder.
Many of these have died quick deaths, on account of their practical
imperfections. But one, at least, may be pronounced a success--the
Lawrence-Kennedy cow-milker, which is worked by electricity, and
supplies another proof of the adaptability of the "mysterious fluid" to
the service of man.
On the Isle de la Loge in the Seine is a dairy farm which is most
up-to-date in its employment of labour-saving appliances, including
that just mentioned. Here a turbine generates power to work vacuum
pumps of large capacity. The pumps are connected to tubes terminating
in cone-shaped rubber caps that can be easily slipped on to the teat;
four caps branching out from a single suction chamber. As soon as they
have been adjusted, the milkman--now shorn of a great part of his
rights to that title--turns on the vacuum cock, and the pulsator, a
device to imitate the periodic action of hand milking, commences to
work. The number of pulsations per minute can be regulated to a nicety
by adjusting screws. On its way to the pail the milk passes through a
glass tube, so that the operator may see when the milking is completed.
This method eliminates the danger of hand contamination. It also
protects the milk entirely from the air, and it has been stated that,
when thus extracted, milk keeps sweet for a much longer time than
under the old system. The cows apparently do not object to machinery
replacing man, not even the Jersey breed, which are the most fidgety of
all the tribe. Under the heading of economy the user scores heavily,
for a single attendant can adjust and watch a number of mechanical
milkers, whereas "one man, one cow" must be the rule where the hand is
used. From the point of romance, the world may lose; the vacuum pump
cannot vie with the pretty milkmaid of the songs. Practical people
will, however, rest content with pure milk _minus_ the beauty, in
preference to milk _plus_ the microbe and the milkmaid, who--especially
when she is a man--is not always so very beautiful after all.
CREAM SEPARATORS
In the matter of separating the fatty from the watery elements of milk
machinery also plays a part. The custom of allowing the cream to "rise"
in open pans suffices for small dairies where speed and thoroughness of
separation are not of primary importance. But when cream is required in
wholesale quantities for the markets of large towns, or for conversion
into butter, much greater expedition is needed.
The mechanical cream separator takes advantage of the laws of
centrifugal force. Milk is poured into a bowl rotating at high speed
on a vertical axis. The heavier--watery--portions climb up the sides
of the bowl in their endeavour to get as far away as possible from the
centre of motion; while the lighter particles of cream, not having
so much momentum, are compelled to remain at the bottom. By a simple
mechanical arrangement, the--very--skim milk is forced out of one tube,
and the cream out of another. An efficient separator removes up to 99
per cent. of the butter fat. Small sizes, worked by hand, treat from 10
to 100 gallons of milk per hour; while the large machines, extensively
used in "creameries," and turned by horse, steam, electric, or other
power, have a capacity of 450 gallons per hour. The saving effected
by mechanical methods of separation is so great that dairy-farmers
can now make a good profit on butter which formerly scarcely covered
out-of-pocket expenses incurred in its manufacture.
A MACHINE FOR DRYING MILK
Milk contains 87 per cent. of water and about 12 per cent. of nutritive
matter. Milk which has had the water evaporated from it becomes a
highly concentrated food, very valuable for many purposes which could
not be served by the natural fluid. Until lately the process of
separating the solid and liquid constituents was too costly to render
the manufacture of "dried milk" a profitable industry. But now there is
on the market a drying apparatus, manufactured by Messrs. James Milnes
and Son, of Edinburgh, which almost instantaneously drives off the
water.
The machine used for this--the Just-Hatmaker--process is simple.
It consists of two large metal drums, 28 inches in diameter and 5
feet long, mounted horizontally in a framework with a space of about
one-eighth of an inch between them. High-pressure steam, admitted to
the drums through axial pipes, raises their surfaces to a temperature
of 220° Fahr. The milk is allowed to flow in thin streams over the
revolving drums, the heat of which quickly evaporates the water. A
coating of solid matter gradually forms, and this is scraped off by a
knife and falls into a receptacle.
The milk is not boiled nor chemically altered in any way, though
completely sterilised by the heat. This machine promises to
revolutionise the milk trade, as farmers will now be able to convert
the very perishable product of their dairies into an easily handled and
imperishable powder of great use for cooking and the manufacture of
sweetmeats. Explorers and soldiers can have their milk supply reduced
to tabloid form, and a pound tin of the lozenges will temper their tea
or coffee over many a camp fire far removed from the domestic cow.