tter is done in various types of presses. In one of the most
frequently used types, the mass is poured into circular steel pots, the
top and bottom of which are loose perforated plates lined with felt
pads. A number of such pots are placed one above another, and then
rammed together by a powerful hydraulic ram. They look like the parts of
a slowly collapsing telescope. The "mass" is only gently pressed at
first, but as the butter flows away and the material in the pot becomes
stiffer, it is subjected to a gradually increasing pressure. The ram,
being under pressure supplied by pumps, pushes up with enormous force.
The steel pots have to be sufficiently strong to bear a great strain, as
the ram often exerts a pressure of 6,000 pounds per square inch. When
the required amount of butter has been pressed out, the pot is found to
contain not a paste, but a hard dry cake of compressed cocoa. The
liquified cacao bean put into the pots contains 54 to 55 per cent. of
butter, whilst the cocoa press-cake taken out usually contains only 25
to 30 per cent. The expressed butter flows away and is filtered and
solidified (see page 158). All that it is necessary to do to obtain
cocoa from the press cake is to powder it.

[Illustration: SECTION THROUGH CACAO PRESS-POT AND RAM-PLATE.]

(_j_) _Breaking Down the Press Cake to Cocoa Powder._

The slabs of press-cake are so hard and tough that if one were banged on
a man's head it would probably stun him. They are broken down in a
crushing mill, the inside of which is as full of terrible teeth as a
giant's mouth, until the fragments are small enough to grind on steel
rollers.

(_k_) _Sieving._

As fineness is a very important quality of cocoa, the powder so obtained
is very carefully sieved. This is effected by shaking the powder into an
inclined rotating drum which is covered with silk gauze. In the cocoa
which passes through this fine silk sieve, the average length of the
individual particles is about 0.001 inch, whilst in first-class
productions the size of the larger particles in the cocoa does not
average more than 0.002 inch. Indeed, the cocoa powder is so fine that
in spite of all precautions a certain amount always floats about in the
air of sieving rooms, and covers everything with a brown film.

(_l_) _Packing._

The cocoa powder is taken to the packing rooms. Here the tedious
weighing by hand has been replaced by ingenious machines, which deliver
with remarkable accur