Year: 1871

10 increase 10 an apprecliDle extent tnat oil the
canejuice to which the mixture is added only in
the proportion Of from 2 to per cent, serves to
keep isolated, and in pure state, the fine parti.
cles which constitute the powder under form Of
which the sulphite Of lime has been obtained. 1t
prevents in fact their change on their surface
into mixture of Sulpkate and Sub-Sulphite.
which, enveloping them as it were in shell,
renders them unadapted to be submitted to the
action Of weak and diluted acids.


To resume, then


l. The sulphite of lime must be prepared at
the same moment that it is to be employed
| 2. 1t must be obtained in the form Of very
fine powder.


3. 1t must be retained in the liquid in the form
in which it has been made so that the particles
or grains of which it is constituted shall remain
isolated and entirely pure.


| Before using the lime in the preparation Of the
sulphte it will always be well to wash it, as by
this means the small quantity of soluble salts it
contains will be removed


MODE OF EMPLOYMENT FoR cASE-JUIcE.


Mono-Sulphite of Lime being insoluble, neces-
states certain precautions if it is to be success
fully employed. 1t is not sufficient that it should
be mixed with the cane,juice, but care must be
taken that it is in contact with the sugar,juice
during the greater part Of the time occupied in
the process of evaporation.


When the cane-iuice flows from the rollers of
the sugar-mill it ought to be rapidly cleared from
all the bits of cane-trash it brings with it by
means of strip OF brass net. 1t should then be
allowed to settle in the tank from eight to ten
minutes so as to allow Of the precpitation of the
finer particles of trash which the sieve has let
pass.


During this time, in order to prevent any
! fermentation, the surface of the cane-juice is
sprinkled with small quantities of the sulphite Of
lime mixture3 which will accumulate in great
measure in the scum thrown up, and will ulti-
mately be found at the bottom of the tank when
the canejuce is run out.


The cane juice is then conducted to the evapor-
ating apparatus. and to it is to be added from 2
to per cent Of the yellowish liquid, or slightly
acid liquid containing the sulphite of lime in
suspension.


By the movement given to the cane juice, the
sulphte of lime, owing to the smallness of the
particles 10 which it has been obtained. spreads
easily over the whole mass of the sugar-liqud,
upon which it will soon exercise its double
influence, that is to say, its purifying an deeolor-
izing action


Here it must be observed that there are two
methods of operation, depending on, lst, whether
the cane juice is TO be sent directly into the bat
terry (boilingpaus) or, %, whether it has to
submit to preliminary DELEGATION in double
bottomed tanks heated by steam, and then con
centrated in the battery, or in the trippleeifect
apparatus.


l. In the first case the chief care during the
open fire evaporation process should be the isoIa-
tion of the scum thrown up in the first two boil
ing pans, and to prevent its mixture with the
liquid contained in the forward pans. The surest
means to obtain this result is to make use Of a
plank fixed at Is inches below the surface Of the
liquid, aud adjusted throughout the length of the
partition which separates the second and third
pans, and to form an opening in the middle of
the plank in which should be placed moveable





the purified canejuice to pass free from scum.


But there is one popularity which can not be
too mach insisted on as upon it depends entirely
the success Of the process it is that which con-
Germs the reaction in the sugarjniee II is es-
sential that this reaction be slightly acid during
the whole duration Of the work. not alone when
the juice is ia the battery, but when the clarified
juice after sufficient decanterug, is concentrated
in the vacuum pan, or in a low-temperature Gp-
paratus The naturalization Of this acidity, even
for moment, will inevitably lead to modification
in the results the process is destined io realize.
At the same time it would be wrong to allow
this acidity to develop itself beyond certain
degree for pushed too far it will cause great in
conveniences Here, again, the litmus parper is
to be employed, so as to ascertain the precise
limit which should be preserved 4 slip Of this
paper plunged in the different pans viii constantly
indicate tue acidity, which increases as the last
pan is approached; and this is explained by the
fact Of the concentration Of the liquid and the
liability Of the cane juice to become acid nnder
the influence Of heat II no lime were added,
the natural acidity of the juice, which is gradually
evaporating would exceed the degree necessary
to be maintained.


1t is requisite, then, to throw on the boiling
surface in the fourth and ifth pans, land there
only,l certain quantity Of very weak lime and
water, in such way as 10 reduce the acidity Of
the sugar liquid when that acidity augnenis be-
yond measure; but too large quantity Of lime
and water must be carefully avoided fJr it is inn
pOrtant that the acid or acids Of the juice shall
never be altogether neutralized.


To determine this essential point in the process,
it must be stated that the acid reaction to be
maintained ought to be such the. the clarified
juice marking 20 to % Beaume shall radder
the litmns paper to a somewhat greater extent
than when it "a placed 10 the cansjace directed
into the battery.


The careful observation Of this degree Of scidity
is most important In point Of fact, the acidity
to be maintained should be only somezhai more
apparent than that which is natural to the cane
juice.


By acting in the way described, the quantity
Of sugar irterverted "a has haan ubour h. ,r