, 1881-05-04

facture, there is only one critical time
when by inattention or negligence on
the part of the head wall-man the SUI
gar may be materially damaged. Al
though wandering a little from my
subject, it may not be out Of place for
mi to briefly point out here when this
critical time occurs, and of what the
danger consists, that is to be appre-
hended. The difficulty is the deter
mining the exact moment when the
boiling of the sling in the striking
teache must cease, or in other words,
the exact moment when to make a
skip great skill and experience being
required to determine the exact boil
ing time suitable for every kind OF
juice. The main point is to bring
about crystallisation in the sling in as
great mass as possible after it cools ;
for if the sling be taken out of the
teache too 500 there will be seen in
it, after cooling, only a few large irreg-
ular crystals, and a quantity of sugar
will be left in the molasses on the
other hand if the sling has been allow
ed to boil too long a sticky mass of
very tiny crystals and syrup will
result, from which the molasses can
not be drained off ut all, or only
with great difficulty, and from which
it will be impossible to obtain clean,
dry and hard crystals. An expert
enced wall-man knows, from the APP
pearance of the waves and bubbles,
the approach of the striking point, but
if a test is wanted the best / know
of is the following. Take a tin cup
of the boiling sling and pour a spoon
full of it into a glass Of clear
water if after a minutes cooling the
sling can be formed into a ball which
does not stick to the fingers, and
which slightly ffattens itself on,
the bottom of the glass by the mere
weight of its descent if dropped in,
the correct period has arrived for
striking,-I will now proceed to the
vacuum pan.
In as few words as possible, @ C
pan is a globular or pear shaped vessel of
hard copper or cast iron (the former is the
best) Of from 6 to 10 feet in diameter, pro.
vided with a steam jacket over it's lower
portion, and with three or six large and
long coils, or h~elices, of copper steam pipe
in it's interior. At the lowermost part of
the PAL there is an outlet which is closed
with aside valve or other suitable arrange.
ment, and on the top it has a wide neck
leading to the conde nsing apparatus, and
vacuum pump.
There is an arrangement in its side, or
near the top, for taking samples or sSproofs"
of the sugar when boiling al inlet for the
admission of the syrup which is to be boil
ed, an air cock, thermometer and vacuum
guage and two or more bulls eyes or peep
glasses through which to watch the pro-
gress of the boiling. The condenser Is
usually an iron vessel or cylinder from
two to four feet in diameter furnished with
a supply of water which falls ON to a per-
forated tray; a largo pipe passes from ito
bottom to the pump to take off the water
used in condensing the vapour coming
from the pan, and there is a delivery pipe
from the pump to carry away the water
outside. The vacuum pump is generally
twenty inches in diameter, makes q two
foot stroke, and is capable of removing so
much of the air from the pan that what
remains has only elastic force enough to
support a column of mercury two inches in
height instead of the thirty inches, which
it does when at full pressure.
In using the vacuum pan the pumpS ara