assorted sizes and get the sand by itself, we would pass the mass through
a series of sieves of gradually smaller mesh. The first sieve of course
would catch all the largest pebbles, the next in size would let all the
second sized gravel through, and so on until the final sieve would have
separated the coarse sand from the fine. In this figure of illustration,
the coarse pebbles may be taken to represent the water and the fusel oils
which are mixed and partly tend to rise with the alcohol, and the alcohol
may be represented as the gravel larger than the sand, and the fine sand
as the etheric vapors. If this gravel were forced upwardly through a
series of sieves gradually growing finer, it would be analogous
figuratively to the upward passage of the vapors through a distilling
column composed of plates or chambers; the water and fusel oils would be
retained in the lower portion of the column and continually sent back
there; the alcohol would pass into the upper chambers of the column and
the ethers or fore-shots would pass out from the very fine sieve at the
top of the column.
The vertical chambers above each plate of the rectifying column are
to-day used as the separate eliminating chambers referred to above. It
has been found in practice that as before stated, each plate of a column
contained upon it liquid of a certain temperature and above it vapors of
a certain degree of vaporization. That is, in a continuous column fed
regularly by condensation from above and supplied with a constant flow of
phlegm, each plate carries upon it a liquid of constant composition
relative to the boiling point of the fluid on that plate. As many
extractions may thus be made from the various plates as there are
different liquids to be isolated. Thus by tapping different portions of
the column, vapors of different degrees of vaporization are found and may
be carried off and the phlegm be thus fractionated. In the case of one
column the first runnings or fore-shot would be found in the upper
portion of the column to which they would have risen by reason of their
degree of volatility. The last runnings or oils, aldehydes, etc., would
be found in the lower portion of the column still mixed with the spirit,
while upon the plates of the middle portion of the column would be found
the vapor of the alcohol freed from the fusel oils and from the,ethers.
It is understood, of course, throughout this description that the liquid
being treated is not wash but phlegm; that is, the raw spirit containing
the fusel oils, ethers, water and alcohol.
Fig. 38 represents a simple rectifying apparatus designed for small or
medium sized plants, and manufactured by the Vulcan Copper Works Co., of
Cincinnati. The still is upright, with a chambered column above it, of
the usual type. The chambers are fitted with a vapor boiling pipe and cap
and a drop pipe, and each is provided with cocks whereby it may be
drained for cleansing. Above the column is a separator, comprising a
casing containing a series of tubes. The vapor from the column circulates
around the tubes through which passes a current of cool water. The
condenser is of the same construction as the separator and is provided
with a gage glass and a draw-off cock. The operation is the same as in
other simple rectifiers; part of the vapor from the column is condensed
in the separator and passes back on to the upper plates, while the more
highly vaporized portions pass over into the condenser.
[Illustration: FIG. 38.--Rectifying Apparatus with External Tubular
Condenser. (_To face page 94_)]
The diameter of the still is large relatively to its depth so as to yield
an economical and at the same time highly effective distribution of heat
through the charge. This also affords an extended boiling area from which
the vapor rises evenly and regularly, thus ensuring conditions peculiarly
conducive to produce the best fractionating. The floor space required for
this still and others of the same character built by this company is very
compact and excessive weight on the top floor of the building is
dispensed with.
We have shown in Figs. 39 and 40 two forms of rectifying apparatus, one a
twin column Barbet rectifier and the other a rectifier of the Gillaume
type combined with inclined column still.
[Illustration: FIG. 39.--Twin Column Barbet Rectifier.]
In the twin column apparatus, Fig. 39, the first column or clarifier _A_
receives the raw phlegm and accomplishes the elimination of ethers. The
clarified phlegm passes then to the second column where the alcohol
is separated from the last runnings or fusel oil. In other words, the
phlegm or impure raw alcohol is only raised to such a temperature in the
first column as to drive off the very volatile constituents such as the
ethers. These therefore pass off at the top of the first column into the
condenser _C_, the retrogradation or condensed alcohol being returned to
_A_, while the boiling phlegm taken from the middle of the column and
still containing the aldehydes, oils, etc., is conducted by a pipe _E_ to
the second column _B_ wherein the last runnings or amylic oils, etc., are
separated from the purified spirits.
The vapors in this column are carried to the condensers _D_ and _F_ and
from there to a refrigerator _G_. The fusel oils are extracted from the
plates slightly below the center of the column and are carried to an oil
concentrating apparatus _H_.
In the most complete forms of apparatus used to-day, there is a variation
of this construction. The first runnings, middle runnings and the last
runnings are each led off from the main column to separate coolers,
condensers, etc., and the purified result from each of these columns is
in turn led to a trunk rectifier common to all where the product is
redistilled and entirely freed from impurities. This gives a very high
grade of alcohol by a process practically continuous. At the same time
the impurities are not returned to the first or main column to
contaminate the vapors therein and add to the amount of fusel oils
contained on the lower plates. In construction of this character there
is a very large saving in the cost of the fuel and the result is much
better in every way.
[Illustration: FIG. 40.--Gillaume's Rectifier and Inclined Still.]
FIG. 40.--GUILLAUME'S DIRECT DISTILLATION-RECTIFICATION APPARATUS FOR
"AGRICULTURAL" DISTILLATIONS.
_A_ Distilling Column.
_a_ Tank for Wash to be Distilled.
_b_ Cold Water Tank.
_C_ Rectification Column.
_D_ Final Purification Column.
_I_ Wash Heater.
_K_ Condenser.
_K¥_ Refrigerator of Ethers.
_O_ Refrigerator for high-grade Alcohol and the First Runnings.
_Q_ Refrigerator for the Products of the Last Runnings.
_R_ Spent Wash Extractor.
_r_ Siphon Carrying off Spent Wash.
_S_ Steam Regulator.
_s_ Tap and Pipe for Carrying Wash to Distilling Column.
_U_ Water Regulator.
_u_ Taps for the Extraction of Intermediate Impurities.
_V_ Receiver Accumulator.
_v_ Tap for the Extraction of the Last Runnings.
_X_ Test Glass for the High-Grade Alcohol.
_Y_ Test Glass for First Runnings.
_Y¥_ Test Glass for Last Runnings.
_Z_ Test Glass for Determining Degree of Exhaustion of Spent Wash.
In this apparatus the still proper is of the form heretofore described on
page 78. The liquid to be distilled enters at the top of the inclined
column _A_ and descends to the base thereof. The alcoholic vapor rises
through the column and passes off from the head thereof into the
rectifying column. At the head of the column _A_ it has a strength of
about 40∞ to 50∞ F. The column _C_ is supported upon an accumulating
reservoir _V_ which acts to regulate the flow of the phlegm through the
rectifying column and prevents too great an exhaustion of the plates of
the column. It acts as a reservoir to contain any excess of phlegm or to
supply an additional amount of phlegm to the plates when they have become
nearly exhausted.
The oils or products of the last running accumulate at the base of the
column, and are carried off to their special refrigerator _Q_. The
alcoholic vapors concentrate while rising in the column and quickly
attain a strength of 92∞ or 94∞ F. At a height within the column
corresponding to the plates whereon alcohol of that strength is to be
found, there are provided three taps _u_ whereby the middle runnings or
medium grade of alcohol may be drawn off, which have a maximum
concentration of 92∞ and 94∞ F. Above these middle plates the alcohol
vapors are completely separated from the products of the "tail" that is
the aldehydes, amylic oils, etc., and at the upper portion of the column
there is found the condenser _K_ which separates the products of the
head; that is the first runnings from the alcohol which has passed over
with such products to the condenser. The alcohol so separated is
completely rectified in the column of final purification _D_ and the
finished alcohol is cooled in the refrigerator _O_ below the column of
final condensation. In this apparatus the gauge glasses which regulate
the exit of the various alcohols and mixtures are controlled by taps
having verniers or scales whereby they may be very carefully adjusted, to
regulate the relative proportion of the various products. This apparatus
is able to produce about 75 or 80 per cent. of first-class alcohol, 10 to
15 per cent. of middle class alcohol, and 5 per cent. of ethers and 5 per
cent. of fusel oils, the alcohol produced being about 96∞ Cartier.
The alcohol is thus obtained in one single operation and with, it is
asserted, only a very small loss in rectification. The apparatus is
claimed to be so simple that it may be operated even by unskilled farm
labor. It is also claimed that purification by chemical treatment or
filtration is unnecessary with the Guillaume apparatus. It may be stated,
however, that the Guillaume system has many opponents.
The capacity of the rectifying apparatus has a good deal of influence
upon both the quantity and the quality of the spirit obtained. Besides
being much more difficult to manage, a small apparatus will not yield so
large a proportion of spirit as a more capacious one, nor will its
products be of equally good flavor. The proportion of alcohol which may
be obtained from a successful rectification is very variable; it depends
upon the nature of the spirit rectified, the method of extracting the
sugar, and the manner of conducting the distillation; it will also be in
inverse proportion to the quantity of fusel-oil contained in the raw
spirit. The average loss of pure alcohol during the process of
rectification is generally estimated at about five per cent.
In addition to the rectifying as above described, alcohol may be further
purified by filtration through charcoal, by chemical means or by
electrolysis. The last two methods have not so far been successful. The
chemicals used merely act to disguise the disagreeable taste or smell of
the spirit and do not really purify. They but substitute one impurity for
another. The agents used are many--sulphuric and nitrate acids, soaps,
oils and fats soda, lime and potash have each and all been tried, but
with no permanent success. As agents for disguising the taste of new and
raw spirits, alcoholic extracts of fruits have also been used.
Purification and aging by electricity has been tried many times and in
many different forms, but so far has not been commercially practicable.
Filtration still remains the best and simplest adjunct to the rectifier.
In small plants, a filter bed several feet in thickness of bone black
or beachwood or charcoal is used, laid upon a foundation of gravel in a
filtering tank. In the larger plants a series of these vats is used, the
charcoal being used in lumps varying from 1/4 to 1/2 inch in diameter.
Two different views of the purification by charcoal are held--one that
the charcoal purifies by chemical means, the other that it is purely a
physical filtration agent. After filtration the charcoal must be steamed
to recover the spirits retained therein and should be heated to a red
heat every now and then to cleanse and regenerate it.
CHAPTER VI.
MALTING.
Wheat, oats, rye, potatoes, and other amalyceous or starchy materials
contain starch insoluble in water and to render it soluble, and to change
the starch to maltose they must be mashed with a certain small proportion
of malt,--or grain in which germination has been artificially induced and
then interrupted at a certain stage. This increases the diastase
contained in the grain so germinated, and this diastase is able to
transform starch into soluble form. Hence, malted grain gives lightness
and liquidity to the wash, and prevents the starch falling to the bottom
of the mash tub or "back," and also prevents the starch falling to the
bottom of the still and consequent burning.
While all varieties of grain including rice are suitable for the
preparation of malt, barley is preferred to all others, and is most
commonly used.
=The best barley= for malting is that having the following
characteristics; a thin skin; a mealy interior; grains of a uniform size;
of the greatest weight; which has been stored for three months. Barley on
harvesting has but slight germinating power. The reason for the
uniformity in the grains lies in necessity of a uniform steeping of the
grain so that the period of germination shall be the same for the whole
mass.
Like all materials for distillation, the barley should be thoroughly
cleaned of impurities--not only dust, seeds and weeds, but fungi and
bacteria.
This may be partly accomplished in the ordinary fanning mills, usual on
farms, but a better machine would be a "tumbling box" of wire mesh. This
is inclined, so that grain put in the upper end, will pass downward to
the lower, being thrown about as the box or cylinder is rotated. The
dust, seeds, etc., fall through the meshes of the wire as do the smaller
grains. After this cleaning, the barley should be thoroughly washed. This
may be either done in the steeping vat itself--and the water afterwards
drawn off--or in special machines. If the barley be allowed to soak in
water for a day or two, the later washing will completely cleanse it.
This preliminary cleaning is most important as impurities reduce the
germinating power of the grain, as well as introduce bacteria inimical to
fermentation.
Washing in some instances is done by forcing compressed air into the
steeping tub, thus violently agitating and swirling the water therein,
and washing away the impurities. Another method is by passing the steeped
grains along a trough supplied with moving water, the trough being
provided with rotary agitators. Any fairly ingenious mechanic could
devise a capable cleansing machine. Care being taken that it shall not
injure the grains.
After cleansing, the barley should be steeped. For this purpose tanks of
metal or cement are to be preferred to wood. All vats should be kept
thoroughly cleaned by frequent scrubbing with lime water.
The barley placed therein should at all times be entirely covered with
fresh water to a depth of a few inches, and for the first few hours the
grains should be carefully stirred in order that no grain should escape
wetting. At the end of that time the still floating grains should be
removed.
In 36 or 48 hours the grain will usually be sufficiently steeped,--but
this varies with weather conditions. The warmer the water the quicker the
steeping, and in winter proper steeping may not be accomplished before
four or five days.
A simple test is to rub the grain strongly between the hands, If it is
entirely crushed, and no solid matter is left it has been steeped
sufficiently. Barley should be capable of compression lengthwise and the
hull should become easily detached. It should be easily bitten, and not
crack under the teeth. In order to prevent fermentation in summer, it is
well to renew the water a few times during steeping. Over steeping is
worse than under steeping.
After the barley is in proper condition the vat or tank is opened and the
water drained away. The draining should be complete, and therefore the
grain should be left to drain about 12 hours.
=Germinating.= The grain is now taken to the malting floor. In practice
it is well to locate the steeping vat above the malting floor, so that
the steeped grain may be run down on to the floor without inconvenience.
It is best to first spread the grains out on the floor to a depth of a
few inches in order that it may somewhat dry out. This is not necessary
when it has not been steeped to a great extent.
After 10 or 12 hours of drying, the grain is placed in a heap until warm
to the touch, which may occur in from 12 to 24 hours. It is then disposed
in a layer from eight inches to 20 inches thick. This is called the "wet
couch." The lower the temperature the thicker the couch should be. It
should be turned every six or eight hours in this stage.
The heat so germinated after 25 or 30 hours produces at the end of each
grain a small white rootlet. The grain in the middle of the layer is the
first to sprout, as it is the warmest, hence the couched grain should be
frequently turned so as to give all the grains a uniform heat, and a
uniform germination. At this period the grains beneath the surface are
dampish to the touch.
The height of the couch is now successively lessened to layers of from
six to two inches called "floors," the height of each floor of course
depending on the temperature, as before.
It is to be understood that the growing grain requires both dampness and
air, hence the "floor" should not be thinned so rapidly as to deprive it
of moisture, and the barley should be turned at least twice a day to give
each grain a proper aeration. During this period the small white rootlets
or radicals should be white and shiny. If they begin to fade, it is a
sign that they lack water and the grain should be sprinkled. Germination
usually requires from a week to ten days, or sometimes two weeks,
depending on the previous steeping, the quality of the grain and the
temperature. When the fibers or rootlets of the grain are about equal to
the length of the grain, germination is complete.
It used to be considered that malt was in its best condition in eight or
ten days. To-day, however, "long malt" is used,--requiring a germinating
period of twenty days, being frequently moistened and turned during this
time, and the temperature being kept at 65∞ F. This malt is very strong
in diastase.
The effect of germination is to produce a change particularly favorable
to mashing. The barley becomes sweetish, the gluten is partially
destroyed and what is left is soluble. Thus the fecula or starch is set
at liberty and free to be acted on by the yeast used in fermenting.
March is the best month in which to malt; and while the malt is best used
immediately, it can not be kept in its green state and must be therefore
dried for future use.
=Drying.= This is accomplished either in the air of a warm, dry room in
hot weather, or by means of a drying kiln. In the first process the malt
is spread in a thin layer and frequently turned. In the second the grain
is spread out in a layer from eight inches to a foot thick on the grain
floor of the kiln.
Beneath the grain floor a fire is maintained. In the beginning the
temperature of the drying floor should be about 85∞ F., but this is
increased gradually to about 104∞ F. until most of the moisture has been
removed. The heat is then raised to from 120∞ F. to 130∞ F., thus
completely drying the grain.
The germinated green or dried barley is called malt. It is of good
quality when the grain is round and flowery; when it crumbles easily and
when its taste is sweetish and agreeable. Pale malt or that which has
been hardly altered from its original color is the best for distillation.
Before the malt can be used it should be screened so as to remove the
rootlets.
Two hundred and twenty lbs. of barley should yield from 275 to 350 lbs.
of green malt, about 200 lbs. of air dried malt, and from 175 to 190 lbs.
of kiln dried malt.
In large plants malting is now so carried on that the steeping
germination and drying are all accomplished in one vessel or container,
by one continuous operation. This vessel is commonly in the form of a
drum of sheet iron, revolving at a very slow speed. Moist air is
introduced and the carbonic acid laden air withdrawn. After germination
the malt is dried by passing in dry air at the proper temperature.
As these systems are only adopted to large distilleries, using expensive
machinery, further reference to them is not considered necessary in this
volume.
Previous to use the malt must be finely ground or crushed either before
or after mixing with the materials to be mashed. It is not necessary or
advisable that the malt be reduced to flour. The use of malt with other
materials in order to form a fermentible mash, will be considered in the
chapters on specific mashes.
CHAPTER VII.
ALCOHOL FROM POTATOES.
In certain countries, as for instance Germany and France, potatoes form
the greatest source of alcohol, particularly for industrial purposes.
With the possible exception of corn and beets they will probably be most
used in America.
The best potatoes for distilling are those which are most farinaceous
when boiled. In other words, those which are "mealy" and most appetizing.
These give the largest yield of alcohol per bushel. The best season of
the year in which to use potatoes is from October to March, when they
germinate.
The potatoes should be kept in dry cellars, and at even temperatures,
warm enough to prevent freezing and yet not so warm that they will rot or
sprout. Diseased potatoes may however be used, if they have not been
attacked by dry rot, though they are not so easily worked. Frosted
potatoes may be also used, but they must not have been completely frozen.
Before being steamed, the potatoes should be washed, either by hand or by
a machine, care being taken to remove all stones, clods of earth, and
other foreign substances which might impede the subsequent operations.
There are three main methods of saccharifying the fecula or starch of the
potato. The first and most important by reducing the tubers to a pulp,
and malting the entire mass. The second and third, by rasping the
potatoes and so separating the fecula or starch grains from the mass, and
then making a thin liquor or wash containing this fecula.
Originally, in the first process, the washed potatoes were submitted to
the action of boiling water, but later cooking by steam at a temperature
of 212∞ F. was used, as being much more convenient to handle and more
effective in action. The object of steaming is to break the coating and
reduce the contents thereof to a pasty condition, wherein the starch is
more effectively acted on by the malt and yeast. Ordinary steaming does
not, however, render the pulp sufficiently pasty; some of the starch
remains undissolved and is lost, hence in the modern practice, steam is
turned into the steaming vat under a pressure of three or four atmosphere
(45 to 60 lbs. to the square inch).
High pressure steaming will be later described but the simple and older
method of mashing and apparatus therefor, used prior to 1870, was as
follows:
Fig. 41 shows a section of a steaming vat. This consists of a conical
wooden tub _H_ provided at its top with a suitable cover _O_ having a
trap or door _P_ for putting in the potatoes. This as shown, consists of
a hinged lid, having a button _p_ or other fastening means. This lid and
cover should be of course steam tight, and it would be better to have it
clamped down by a screw clamp than held by a button.
Somewhat above the bottom of the vat, a steam inlet pipe _I_ enters,
connected at its other end by a coupling _i_ with a suitable steam
generator (see Fig. 43), Preferably the outlet of this pipe is screened
by a perforated plate _M_ so that it may not be clogged by the pulp. It
is also best that a filling piece be placed at the junction of the bottom
with the sides in order that there be no sharp corner from which the pulp
may not be easily cleaned out.
[Illustration: FIG. 41.--Steaming Vat for Potatoes.]
The bottom of the vat may either have a discharge door at the side as in
Fig. 44 or at the bottom, as in Fig. 41.
An under side view of the latter construction is shown in Fig. 42. The
bottom of the vat is made in two parts or doors _J K_. These are held
closed by a transverse bar _L_ inserted at its end into a stirrup _l¥_
and supported at its other end by a button _l_, or other means.
While various forms of steam generators may be used, Fig. 43 shows a
simple construction well adapted to the needs of a small distillery. _D_
designates the brick work of a furnace, and _A_ the boiler. This is so
set that an annular space _E_ surrounds the sides of the boiler, through
which the products of combustion must pass.
[Illustration: FIG. 42.--Bottom of Steaming Vat.]
The head of the boiler is connected by a pipe _B_ and collar _b_ to the
steam inlet pipe _I_ of the steaming vat, heretofore described, as by the
collars _b i_.
A filling tube _C_ enters the boiler and projects nearly to the bottom,
and the water outlet-pipe _F_ with cock _f_ leads off from the upper
water line. The tube _C_ forms also a safety valve, for if the steam
pressure becomes too great in the boiler and connected vat, it will force
water up and out through the tube. If, however, the water falls below the
level of the lower end of the tube, steam will issue and warn the
attendant that water is too low. It would be best however, to provide a
steam gauge, whereby the pressure of steam in the boiler and vat could be
accurately indicated.
[Illustration: FIG. 43.--Steam Generator.]
It is to be noted that when steamed the potatoes will swell and occupy
more space and that the steam vat should therefore not be much more than
two-thirds filled with potatoes.
With the steaming vat above shown, the potatoes are delivered mixed with
a considerable quantity of water, but a better plan is to have a
perforated false bottom to the tub, whereby the condensed water may be
carried away, the steamed potatoes remaining behind.
[Illustration: FIG. 44.--Potato Steamer and Crusher.]
Two hours of steaming should reduce the potatoes to proper condition,
which may be tested by introducing a pointed iron rod through a suitable
aperture, normally kept closed. If the rod passes freely inward, the
potatoes are done and may be discharged into the crusher, shown in Fig.
44. In this Fig. the steaming vat _A_ is shown mounted above the crusher.
A pipe _B_ with cock _b_ leads to the steam generator. The steamed
potatoes are shoveled out through the door _a_, which is usually held
closed by means of the clamps or buttons _a¥ a¥¥_.
=The crusher= consists of a hopper _C_ whose bottom fits closely against
two adjacent smooth faced rolls _H I_ of iron. These are driven by gears
_D E_. The shafts of these gears have cranks _d d_ whereby it may be
operated. These gears are unequal so that the rolls shall move at
different speeds, and thus one will have a grinding action against the
face of the other. A counter weighted scraper _e_ bears against the face
of the roll.
The crushed potato pulp passes between the rolls and into a bin beneath,
having adjustable walls made of boards _F_, sliding in suitable guides
_f_, from which the pulp may be shoveled into the mashing tank or "back."
The crusher might, however, be arranged to deliver immediately into the
mashing tank, if the latter is provided with means for stirring the
delivered pulp.
The pulp or paste thus made is now placed in a vat, holding about 650 to
850 gals., in which the saccharification takes place. About 2200 lbs. of
the crushed potatoes and 155 lbs of broken malt are introduced, and
immediately afterwards water is run in at a temperature of about 97∞ F.
to 104∞ F., the contents being well stirred with a fork meanwhile. The
vat is then carefully closed for half an hour, after which boiling water
is added until the temperature reaches 140∞ F., when the whole is left
for three or four hours. The process of fermentation is conducted in the
same vat. Alternate doses of cold and boiling water are run in upon the
mixture, until the quantity is made up to 700 or 775 gallons, according
to the size of the vat, and so as finally to bring the temperature to 75∞
F. or 79∞ F. Five and a half to six gallons of liquid brewer's yeast are
then added, and fermentation speedily sets in. This process complete, the
fermented pulp is distilled in the apparatus devised by
Cellier-Blumenthal (see Fig. 15) for distilling materials of a pasty
nature; the product has a very unpleasant odor and taste.
The process above described is the old method of pulping the potatoes by
using steam. Under the modern method, however, and with modern apparatus,
in preparing potatoes for distillation in large quantities, the steaming
of the material is accomplished at one time and under a high steam
pressure. The apparatus is also used for the preparation of corn,
potatoes and other starch-containing substances.
There are many apparatuses which have been devised for the purpose, but
the principle on which they work is practically the same in all cases.
They comprise a closed tank, fitted with stirrers, agitators, or other
means for mixing and comminuting the contents, means for admitting steam
under pressure, means for cooling the mixture to the proper mashing
temperatures, and means for forcing the steamed material out of the tank.
[Illustration: FIG. 45.--Bohn's Steamer and Crusher.]
=The Steamer.= One of the earliest forms of steamer was that of
Hallefreund devised in 1871, and adapted for working on a large scale. A
modified form of the apparatus known as Bohn's steamer and masher is
illustrated in Fig. 45. This comprises a steaming cylinder _A_, having a
securely closed opening _D_ for the introduction of the potatoes.
Centrally through the cylinder passes a hollow shaft _B_, which is
rotated by the power pulley _K_. Hollow arms _b_ project radially from
the shaft _B_. These act as mixers of the mash and as coolers. The shaft
_B_ at one end is connected to a cold water supply pipe _M_ as by a
coupling _C_, the supply pipe being provided with a cock. _E_ designates
a discharge opening for the mash. A pipe _F_ provides for the entrance of
steam into the cylinder. _G_ is a pipe through which malt is put in to be
mixed with the pulp. _L_ is a steam gauge and _J_ a safety valve. _H_
designates a water pipe. For the relation of the steamer to other
apparatus, see Fig. 1.
In operation the potatoes are placed in the cylinder _A_ and submitted to
the action of steam at about 46 lbs. to the square inch, and at a
temperature of from 266∞ F. to 275∞ F.
When disintegrated, the steam is blown off, and the potatoes crushed by
rotating the stirring shaft. As the pulp must be reduced from 275∞ F. to
149∞ F., the mashing temperature, cold water is forced into the stirrer
which chills the blades and quickly cools the mass.
In the vacuum mash cooker shown in Fig. 1, the steaming cylinder is
partly filled with hot water at 140∞ F. to 150∞ F. The potatoes to be
mashed are fed into the cylinder whole. The steamer is then closed and
steam admitted while the mash is stirred until a pressure of 65 pounds is
reached, when the dissolution of the starch is complete. The steam is
then exhausted and the temperature reduced to 212∞ F. To reduce this
temperature to the proper saccharifying point of 145∞ F., the hot air is
exhausted.
Barley malt meal in the proportion of 6 to 10 per cent. is used. This has
been previously mixed with cold water in the small grain masher. The malt
is admitted to the cylinder and thoroughly mixed with the potato, when
the mixture is withdrawn into a drop tub, where it is still further
stirred. It is then cooled as described on page 15 and then fermented.
While the crushed potatoes are being cooled and stirred, a mixture of
green malt with water is prepared in an adjacent vat, and when the pulp
in the cylinder has been reduced to 149∞ F. the malt mixture is
introduced into the cylinder through the pipe _G_, and thoroughly mixed
with the crushed potatoes. The mass is now left to saccharify; the
stirrer being operated at intervals throughout this period. This machine
might be readily modified so that the steam should enter through the
stirrers, by tubes attached to the arms, then the steam may be shut off
and cold water sent into the arms themselves to cool the mash.
A variety of steamer used in various forms and modifications in all the
larger distilleries, is known as the Henze steamer, Fig. 2. In this,
there are no stirrers. The cylinder is conical, and has steam pipes
leading to the interior. At the end of its cone-shaped bottom it
terminates in a blow-off tube, having in it a grate formed of sharp-edged
bars. In operation, steam is introduced at a pressure of one to two
atmospheres until the potatoes are cooked. More steam is then suddenly
admitted at high pressure and the softened potatoes forced through the
grating at the bottom and into the mashing apparatus in a finely divided
state.
In steaming under pressure it is best that the safety valve be so
regulated that the steam will constantly blow off as this action keeps
the potatoes in motion and facilitates disintegration. Care should also
be taken to see that everything about the apparatus is in good condition,
as in working under the high pressures used in the last apparatus there
is liability of explosion. Rust should be particularly guarded against.
With this apparatus a preparatory mash vat is used into which the
contents of the steamers are blown out, malt and water to form milk
having been previously let into the mash vat. Blowing out is accomplished
in 45 or 50 minutes at 130∞ F. and about one-sixth of the charge in the
steamer is retained in the steamer. The mash in the vat is stirred and
cooled and the remainder of the mash blown in raising the temperature to
145∞ F. when the mash is left to stand from half an hour to an hour. With
heavy mashes, rich in sugar, even higher temperatures than 145∞ F. can be
used for saccharifying.
The processes of crushing and saccharifying, above referred to, which are
almost entirely used to-day, require steam. The following methods provide
for the isolation of the fecula or starch, without steam and the
production of a wash of a more watery consistency, therefore easier to
handle in ordinary stills, and with less liability to burn.
Two operations are necessary by this method: First, rasping, or reducing
the potatoes to a finely crushed and pulpy condition by means of a
machine described in the chapter on Beet Mashing; and second, the
separation of the fecula.
To this latter end the potato pulp is placed on a sieve, having side
walls and net work of horse-hair, which is placed over a suitable tub.
Water is run gradually through the pulp and sieve, while the pulp is
rubbed up by hand. When the water comes through clear, then all the
fecula of the pulp has been washed out, and the refuse left in the sieve
can be thrown aside or used as a food for cattle.
=For a mashing tub= of say about 32 bushels capacity, the fecula from
about 800 lbs. of potatoes is used. This is deposited in the mash tub
with sufficient cold water to form a fairly clear paste. About twice as
much water as fecula will bring the paste to proper consistency. This
mixture should be constantly stirred as otherwise the fecula will sink to
the bottom. About 40 gallons of boiling water are then added gradually.
The mixture has at first a milky appearance, but at the last becomes
entirely clear.
This liquid is mashed with about 45 lbs. of malted barley or Indian corn,
ground into coarse flour. In ten minutes the mixture will be completely
fluidified. It is then left to subside for three or four hours when it
will have acquired a sweetish taste and be what is termed as "sweet
mash." The fluid is then further diluted by the addition of sufficient
water to give about 290 gallons of wash. Two or three pints of good yeast
will bring this mixture to a ferment.
A less laborious method of accomplishing the same result is that at one
time used in English distilleries. In this a double bottom tub is used,
something like that shown in Fig. 41, the upper bottom of which is
perforated, and raised above the solid lower bottom. A draw-off cock
opens out from the space between the two bottoms.
Assuming that the tub is of 220 gallons capacity, then from 2 to 20 lbs.
of chaff are spread over the perforated bottom and pulp from 800 lbs. of
raw potatoes placed on that. This is thoroughly drained for half an hour,
through the draw-off cock. The pulp is then stirred while from 90 to 100
gallons of boiling water are added gradually. The mass then thickens into
a paste. The paste is mashed with about 65 lbs. of well steeped malt,
and the liquid left to subside for three or four hours. It is then
drained off through the perforated bottom into a fermenting back or tub.
For this amount of material the back should be of about 300 gallons
capacity.
=The leavings= left in the preparatory tub still contain considerable
starch, and after they are well drained they should be mixed with from 50
to 55 gallons of boiling water. The mixture is then agitated and drained
off into the fermenting back. The sediment left is again sprinkled with
water, this time cold, which is drained off into the back. This
completely exhausts the husks left on the upper bottom. By this process
200 lbs. of potatoes should produce something over 12-1/2 gallons of
spirit.
The objection to the last method described is that the spirit so obtained
is unpleasant to taste and smell, but this would probably not be an
objection for industrial uses.
The only means of obtaining alcohol of good quality from potatoes is to
extract the starch separately and then convert it into sugar. This
saccharification of the starch may be accomplished by sulphuric acid or
by the action of diastase.
By the first of these methods the potatoes are disintegrated in such an
apparatus as the Bohn steamer described on page 118. A mixture is made of
one-third potatoes, two-thirds water, and onetenth part of sulphuric
acid. The mixture is steamed for six or eight hours under pressure. The
mash is then cooled and the acid neutralized by milk of lime. It is then
fermented.
By the second and preferable method, dry or wet potato starch is used,
which is malted, and the saccharine solution fermented with yeast. The
proportions and method for a vat of say 800 gallons capacity are as
follows:
Two hundred and sixty-five gallons of water are mixed with 1100 lbs. of
dry or 1650 lbs. of moist starch. This mixture is well agitated, and 450
gallons of boiling water run in, together with 165 lbs. of malt. The
whole is then stirred energetically and left to saccharify for three or
four hours. The saccharine solution thus formed must be brought to 6∞ or
7∞ Baume, at a temperature of from 71∞ to 75∞ F. To this is then added
1-1/100 lbs. of dry yeast for every 220 gallons of "must." Fermentation
is soon established and usually occupies about 36 hours. After remaining
at rest for 24 hours the "must" is distilled. From each 220 lbs. of
starch there should be a yield of about nine gallons of alcohol,
at 90∞ F.
The fermentation of the potato mash is carried on as described in Chapter
II. For the preparation of malt see Chapter VI.
CHAPTER VIII.
ALCOHOL FROM GRAIN--CORN, WHEAT, RICE, AND OTHER CEREALS.
The different cereals constitute a very important source of alcohol in
all countries, particularly of course for use in the manufacture of
whiskey and gin.
All cereals contain an abundance of starchy substance which under the
influence of diastase,--that is, malt,--is converted into fermentible
sugar. The quantity of sugar and hence the yield of alcohol differs
widely. The following table shows the results obtainable by good
workmanship.
220 lbs. Wheat gives 7.0 gallons pure alcohol
" " Rye " 6.16 " " "
" " Barley " 5.5 " " "
" " Oats " 4.8 " " "
" " Buckwheat " 5.5 " " "
" " Corn (Indian) " 5.5 " " "
" " Rice " 7.7 " " "
In addition to these there are other raw materials containing starch
which are sometimes used, as millet (55 per cent starch), chestnuts (28
per cent.), and horse chestnuts (40 per cent.). The last is very
difficult to work however.
Rice, wheat, rye, barley and corn are more frequently employed than other
grains. Wheat gives a malt which is as rich in diastase as barley. Barley
and buckwheat are added to these in some proportions. Oats, owing to
their high price, are rarely used. Rice, of all the grain is the most
productive to the distillers, but on account of its value as a food is
not much used for the production of alcohol, unless damaged. Corn is the
cereal most largely used for the production of industrial alcohol.
Great care should be exercised in making choice of grain for fermentation
where the best results are desired. Wheat should be farinaceous, heavy
and dry. Barley should be free from chaff, quite fresh and in large
uniform grains of a bright color (see Malting, Chapter VI).
Rice should be dull white in color, slightly transparent, without odor,
and of a fresh, farinaceous taste.
The flour or farinaceous part of grain is composed of starch, gluten,
albumen, mucilage, and some sugar. The following table gives the
proportions of these substances in the commonest grains.
Under certain conditions the albumen or gluten in the grain has the power
of converting starch into saccharine matter. This is better effected by
an acid such as sulphuric acid, or by a diastase. This latter substance
is a principle developed during the germination of all cereals but
especially of barley. It has the property of reacting upon starchy
matters, converting them first into a gummy substance called dextrine,
and then into glucose or grape sugar, see Chapter II.
The action of diastase upon starch or flour made into a paste is
remarkable, 50 grains of diastase being sufficient to convert 220 lbs.
(100 kilogrammes) of starch into glucose. The rapidity of this change
depends on the quantity of water employed, and the degree of heat
adopted in the operation.
TABLE IV.
PROPORTIONS OF STARCH, GLUTEN, ETC., IN PRINCIPAL GRAINS.
Column A = Grains.
Column B = Starch.
Column C = Gluten and other Azotized Substances.
Column D = Detrine, Glucose and similar Substances.
Column E = Fatty Matter.
Column F = Cellulose.
Column G = Inorganic Salts. (Silica, Phosphates &c.)
-----------+-- ----+--------+-------+-----+---------+------
A | B | C | D | E | F | G
-----------+-------+--------+-------+------+--------+------
Wheat }| 65.99 | 18.03 | 7.63 | 2.16 | 3.50 | 2.69
(average }| | | | | |
of five }| | | | | |
varieties)}| | | | | |
Rye | 65.65 | 13.50 | 12.00 | 2.15 | 4.10 | 2.60
Barley | 65.43 | 13.96 | 10.00 | 2.76 4.75 | 3.10
Oats | 60.59 | 14.39 | 9.25 | 5.50 7.06 | 3.25
Indian Corn| 67.55 | 12.50 | 4.00 | 8.80 | 5.90 | 1.25
Rice | 89.15 | 7.05 | 1.00 | 0.80 | 1.10 | 0.90
-----------+-------+--------+-------+------+--------+------
Inasmuch as barley germinates very readily, and develops a larger
proportion of diastase than any other grain, except wheat, it is
generally used as a producer of diastase. Barley germinated according to
proper methods is called malt, and its preparation is fully described in
Chapter VI.
There are many methods of preparing grain for fermentation, but all use
at least two of the following operations:--grinding, gelatinizing,
steeping, or steaming, mashing saccharifying.
=Grinding.= Where cookers or the Henze steamers are not used every form
of grain should be crushed or ground into a coarse flour. This is in
order that the starchy interior may be easily acted on by the diastase.
If the grain is not to be mixed with malt later it must be ground more
finely so that it may be thoroughly penetrated by the water. The grains
should not be ground except as required, as ground grain is liable to
heating and consequent loss of fermentability, and is also liable to
become musty, in which condition it loses much of its fermentability.
=Steeping.= This operation is best carried on in vats or tanks of iron or
cement, for the reason that wood absorbs impurities, which are
communicated to the grain, thus lessening its germinative power. Wooden
vats should be thoroughly scrubbed after use, and be kept continually
whitewashed. The steeping tub should hold about two-thirds more than the
amount of ground grain to be steeped.
Steeping is affected by pouring on to the crushed grain hot and cold
water in such quantity that after 10 minutes or so of brewing the mixture
will have a temperature of 75∞ to 95∞ F.
This warmth makes the water more penetrating. The water should not be
poured in all at once, but a little at a time, until the grain is covered
to a depth of three or four inches. Care should be taken not to let the
temperature get too high, not above 95∞ F., as a temperature above that
point kills the germinating power.
The mixture of crushed grain and water is now stirred for 10 minutes and
then left to subside for half an hour. It is then stirred again and the
mixture left to steep for 30 or 40 hours, depending on the temperature of
the atmosphere, the dryness of the grain, and the character of the water.
In very warm weather the water should be changed every few hours by
running it off through a hole in the bottom of the tub and running in
fresh at the top. This prevents fermentation setting in prematurely.
When the grain swells, and yields readily between the fingers it has been
sufficiently steeped, and the water is run off. This is an old method of
gelatinizing grain, but a better is by the use of cookers or high
pressure steamers as described for potatoes.
=Mashing.= This consists in mixing the coarse flour with malt and then by
means of certain operations and mechanisms bringing it to a condition
most favorable to fermentation through the action of yeast. The mixing of
the raw flour with barley or other malt effects the conversion of the
starch of the grain into maltose. The yeast afterwards converts this
maltose into sugar.
=Saccharifying.= To effect the action of the diastase of the malt on the
grain, in the old methods, boiling water must be poured into the vat
until the temperature of the mass reaches about 140∞ to 168∞ F., the
whole being well stirred meanwhile; when this temperature has been
reached, the vat is again covered and left to stand for four hours,
during which time the temperature should, if possible, be maintained at
140∞ F., and on no account suffered to fall below 122∞ F., in order to
avoid the inevitable loss of alcohol consequent upon the acidity always
produced by so low a temperature. In cold weather the heat should of
course be considerably greater than in hot. It should be also remarked
that the greater the quantity of water employed, the more complete will
be the saccharification, and the shorter the time occupied by the
process.
Having undergone all the above processes, the wash is next drawn from the
mash tub into a cistern, and from this it is pumped into the coolers.
When the wash has acquired the correct temperature, viz., from 68∞ to 78∞
F., according to the bulk operated upon, it is run down again into the
fermenting vats situated on the floor beneath. Ten to twelve pints of
liquid or 5-1/2 to 6-1/2]** fraction] lbs. of dry brewer's yeast are then
added for every 220 lbs. of grain; the vat is securely covered, and the
contents are left to ferment. The process is complete at the end of four
or five days, and if conducted under favorable conditions there should be
a yield of about 6-1/6 gallons of pure alcohol to every 220 lbs. of grain
employed.
There are a number of different methods of mashing, having each its
advantages, and applicable to particular varieties of grain.
We will first consider the mashing of the steeped grain in general by one
of the older and simpler processes.
The grain to be mashed, which has been ground and steeped as before
described, is mixed with malt in the proportion of four to one, or even
eight to one. In addition, three or four pounds of chaff to every hundred
or so pounds of steeped grain should be used.
=Mash.= Water is then run into the mash tub in the proportion of about
600 gallons to each 60 bushels of grain. Its temperature should be
between 120∞ and 150∞ F. During the entrance of water, the mass is well
stirred so as to cause the whole of the grain to be thoroughly soaked and
to prevent the formation of lumps. It is best to add the grain to the
water gradually and to stir thoroughly.
To this mass about 400 gallons of boiling water is gradually added to
keep the temperature at about 145∞ F. During the addition of the boiling
water the mash should be continually stirred so that the action of the
water shall be uniform. This operation should last about two and one half
hours. The vat should be then covered and left to stand from
three-quarters to one hour for saccharification.
Another method of saccharifying is to turn boiling water gradually into
the mash tank until the mixture has acquired a temperature of from 140∞
to 180∞ F. The mass is thoroughly stirred and the tub is covered and left
to subside for from two to four hours, during which time the temperature
should not be allowed to fall below 120∞ F. A small tub needs more heat
than a larger tub, and more heat is required in winter than in summer.
A convenient method of regulating the temperature of the mash tank, would
be by a coil of pipes on the bottom. This would be connected by a two-way
cock to a steam boiler and to a source of cold water. Heat should never
be carried over 180∞ F., and the best temperature is from 145∞ to 165∞ F.
The greatest effect of the diastase of the malt upon the gelatinized
starch is at 131∞ F. For ungelatinized starch this is not great enough,
hence the greater part of the mashing is carried on at the lower
temperature and only towards the end should the temperature be raised to
the maximum 150∞ F.
Every distiller uses his own judgment as to the amount of the mashing
water used, its temperature, the length of time during which the mash
rests, and the length of time for saccharification.
Saccharification may be recognized by the following signs: The mash loses
its first white mealy look, and changes to dark brown. It also becomes
thin and easily stirred. The taste is sweet and its odor is like that of
fresh bread.
Corn and other grain may be mashed conveniently in such an apparatus as
that described on page 10, as used for potatoes the steam being
introduced under pressure.
The water is first placed in the steamer. Steam is introduced into the
water and it is brought to a boil. The corn is then introduced gradually,
the steam pressure increased to its maximum, and the mass blown out as
described in Chapter VII. Hellefreund's apparatus (see page 118) may also
be used with ground corn.
The corn or grain not previously crushed or ground is introduced into a
steamer in the proportion of 200 lbs. of corn to 40 gallons of water. The
steamer should have about 100 gallons of steam space for this amount.
The mashes described above are thick, more or less troublesome to distil,
and only simple stills can be used. By the following method a clear
saccharine fluid or wort can be obtained.
=A mash vat= is used having a double bottom. The upper bottom is
perforated and between the two bottoms is a draw-off pipe and a pipe for
the inlet of water.
Upon the upper perforated bottom is first placed a layer of between two
and three pounds of chaff. Upon this is turned in a mixture of 400 lbs.
corn and malt in the proportions of 1/5 malt to 4/5 grain. Eighty-seven
gallons of water at a temperature of from 85∞ to 105∞ F. is then let in
to the bottom, while the mixture is thoroughly agitated for 10 minutes.
It is then left to subside for half an hour.
After this steeping process, the mass is again agitated while 175 gallons
of water at 190∞ F. are let into the tub while the mass is continually
and thoroughly stirred by mechanical stirrers. Brewing lasts for half an
hour, and the liquid is then left to stand for seven hours.
At the end of this period the grain is covered by clear liquid which is
drained off through the draw-off cock into the fermenting back.
To the contents left in the steeping tank 135 gallons of boiling water
are added as before and the liquid therefrom drawn into the fermenting
back.
It usually requires three infusions to extract the whole of the
saccharine and fermentiscible matters contained in the grain. In some
places, it is customary to boil down the liquors from the three mashings
until they have acquired a specific gravity of about 1.05, the liquor
from a fourth mashing being used to bring the whole to the correct degree
for fermentation, the liquors from the third and fourth being boiled down
to the same density and then added to the rest. In a large Glasgow
distillery, the charge for the mash tubs is 29,120 lbs. of grain together
with the proper proportion of malt. Two mashings are employed, about
28,300 gallons of water being required; the first mashing has a
temperature of 140∞ F., and the second that of 176∞ F. In Dublin the
proportion of malt employed is only about one-eighth of the entire
charge. One mashing is employed, and the temperature of the water is kept
at about 143∞ F. The subsequent mashings are kept for the next day's
brewing.
By this process the grain is entirely deprived of all fermentible
substances which have been carried away in a state of liquid sugar.
The whole operation of preparing and saccharifying grain is to-day
carried on in steamers, such as described on page 11, and cooking
apparatus such as shown in Fig. 1, or in the Henze high pressure steamers
and preparatory mash vats described in Chapter II.
In steaming grain without pressure, the finely crushed grain is poured
slowly into a vat previously nearly filled with water at a temperature of
about 140 degrees F. A little less than half a gallon of water is used
for each pound of grain. Care must be taken to stir the mass constantly
to prevent lumping. When all the corn is mixed in, steam is allowed to
enter and the temperature raised to about 200 degrees F. It should be
left at this temperature for an hour, or an hour and a half, when the
temperature is reduced to 140∞ F. when about 10 per cent. of crushed malt
is added and the temperature reduced to 68∞ F. by means of suitable
cooling devices.
When steam cookers are used, the cylindrical boiler is first filled to
the proper degree with water at a temperature of 140∞ F. The meal is then
let in gradually being constantly stirred the while. The boiler is then
closed and steam gradually let in while the mass is stirred until a
pressure of 60 pounds and a temperature of 300∞ F. has been reached. The
starch then becomes entirely gelatinized, the pressure is relieved, and
the temperature reduced to 212∞ F. and then rapidly brought to 145∞ F.
The malt is added mixed with cold water, at such a stage before the
saccharifying temperature is reached that the cold malt and water will
bring it to 145∞ F. The malt is stirred and mixed with the mash for five
or ten minutes and the mixed mass let into a drop tub when
saccharification is completed. It is then cooled as described.
When the Henze steamers are used the grain may be treated in either the
whole grain or crushed, as the high pressure to which it is subjected and
the "blowing out" act to entirely disintegrate it. In this mode of
operation, water is first let into the steamer and brought to a boil by
the admission of steam. The grain is then slowly let into the apparatus.
The water and grain should fill the steamer about two thirds full. The
steamer is left open and steam circulated through the grain and water
for about an hour, but without any raising of pressure. This acts to
thoroughly cook and soften the grain.
When sufficiently softened the steam escape cock in the upper part of the
steamer (see Fig. 2) is regulated to allow a partial flow of steam
through it and a greater flow of steam is admitted through the lower
inlet. This keeps the grain in constant ebullition under a pressure of 30
lbs. or so. After another period of an hour the pressure in the steamer
is raised to 60 lbs. at which point it is kept for half an hour, when the
maximum steam pressure is applied, and the greater portion of the
disintegrated mass blown out into a preparatory mass tub, into which malt
has been placed mixed with water. The blowing out should be so performed
that the temperature in the mass in the tubs shall not exceed 130∞ F. The
mass is stirred and cooled and then the remainder of the mass in the
steamer admitted to the tub which should bring the temperature of the
mass up to 145∞ F. It is kept at this temperature for a period varying
from half an hour to one and one-half hours and is then cooled to the
proper fermenting temperature.
Another method of softening corn so that its starch is easily acted upon
by the diastase of the malt is to steep it in a sulphurous acid solution
at a temperature of about 120∞ F. for from fifteen to twenty hours. The
mass is then diluted to form a semi-liquid pulp and heated to about 190∞
F. for an hour or two during which the mass is constantly stirred. The
malt is then added, the mass is saccharified, cooled and then fermented.
Another method is to place mixed grain and hot water in a cooker of the
Bohn variety (Fig. 45). After half an hour of stirring and cooking under
ordinary pressure, the steam pressure is raised to 45 lbs. This is kept
up for from two to three hours when the grain is reduced to a paste.
Concentrated muriatic acid equal to 2-1/2 per cent of the weight of
grain is then forced in, under steam pressure. In half an hour the grain
will be entirely saccharified and ready for fermenting.
CHAPTER IX.
ALCOHOL FROM BEETS.
=Cultivation.= The beetroot (_Beta vulgaris_), indigenous to Europe, is
cultivated in France, Germany, Belgium, Holland, Scandinavia, Austria,
Russia, and to a very small extent in England and New Zealand, and to a
very large extent in the United States and Canada. There are many
varieties. The most important to the sugar-maker is the white Silesian,
sometimes regarded as a distinct species (_B. alba_); it shows very
little above ground, and penetrates about 12 in.; it has a white flesh,
the two chief forms being distinguished by one having a rose-colored skin
and purple-ribbed leaves, the other a white skin and green leaves. Both
are frequently grown together, and exhibit no marked difference in
sugar-yielding qualities.
Good sugar-beets possess the following broad characteristics: (1) Regular
pear-shaped form and smooth skin; long, tapering, carrot-like roots are
considered inferior; (2) white and firm flesh, delicate and uniform
structure, and clean sugary flavor; thick-skinned roots are spongy and
watery; those with large leaves are generally richer; (3) average weight
1-1/2 to 2-1/2 lbs., neither very large nor very small roots being
profitable to the sugar-manufacturer; as a rule, beets weighing more than
3-1/2 lbs. are watery, and poor in sugar; and roots weighing less than
3/4 lb. are either unripe or too woody, and in either case yield
comparatively little sugar; the sp. gr. of the expressed juice, usually
1.06 to 1.07, even reaching 1.078 in English-grown roots, indicating over
14 per cent. of crystallizable sugar, is the best proof of quality; juice
poor in sugar has a density below 1.060; (4) in well-cultivated soil, the
roots grow entirely in the ground, and throw up leaves of moderate size.
=Composition of the Roots.= Internally the root is built up of small
cells, each filled with a juice consisting of a watery solution of many
bodies besides sugar. These include several crystallized salts (mostly of
which are present in minute traces only), such as the phosphates,
oxalates, malates, and chlorides of potassium, sodium, and calcium, the
salts of potash being by far the most important; and several colloid
bodies (albuminous [nitrogenous] and pectinous compounds); as well as a
substance which rapidly blackens on exposure to the air. The greater part
of the sugar in ripe beets is crystallizable, and, when perfectly pure,
is identical in composition and properties with crystallized cane-sugar;
but it is more difficult to refine this sugar so as to free it from the
potash salts, and commercial samples have not nearly so great sweetening
power as ordinary cane-sugar. Beets contain no uncrystallizable sugar;
the molasses produced in beet-sugar manufactories is the result of
changes which cannot be entirely avoided in extracting the crystallizable
sugar.
=Soil.= The best soil for beets contains a fair proportion of organic
matter, is neither too stiff nor too light, and crumbles down into a nice
friable loam; it must be capable of being cultivated to a depth of at
least 16 in. The subsoil should be thoroughly well drained, and rendered
friable by autumn-cultivation and free admission of air. A deep friable
turnip-loam, containing fair proportions of clay and lime, appears to be
the most eligible land for sugar-beets. Lime is a very desirable element.
Well-worked clay-soils, especially calcareous clays, are well adapted, if
properly drained and of sufficient depth. Peaty soils and moorlands are
quite unsuitable, as well as lands which are too dry, like the thin
gravelly soils resting on siliceous gravel sub-soils, or too wet and
cold, like many of the thin soils above impervious chalk marl.
Speaking generally, the best soils for sugar-beet are precisely those on
which other root-crops can be grown to perfection, that is, land which is
neither too heavy nor too light, which has a good depth, is readily
penetrated by the roots, and naturally contains lime, potash, clay, and
sand, as well as organic matter, is such proportions as in good friable
clay-loams. An analysis of the soil should be made previous to planting
it with the sugar-beet, as the salts presented in solution in the soil
will pass into the juice, and greatly interfere with the processes of
sugar manufacture. Certain soils may be at once indicated as unsuitable;
they are clover-land, recent sheep-pastures, forest-land grubbed during
the preceding 15 years, the neighborhood of salt works, volcanic and
saline soils of all kinds. The beet requires a certain supply of potash
and soda salts in the soil, but if these are present in excess, as in
recent forest-land, the juice does not work well, nor give its proper
yield of sugar.
=Manures.= Sugar-beets should be grown with as little farmyard manure as
possible; when dung has to be used, as in the case of very poor soils, it
should be applied in autumn, or as early as possible during the winter
months. The effect of heavy dressings of animal nitrogenous matters or
ammoniacal salts, is to produce abundance of leaves, and big watery
roots; the latter are comparatively poor in sugar, and contain potash
salts derived from the animal matters, which greatly interfere with the
extraction of sugar in a crystallized state. Common salt, and saline
manures in general, though useful in moderate doses (224 lbs. to 336 lbs.
per acre on light soils), should be avoided on the majority of soils, for
sugar-beets grown on soils highly manured with common salt produce juice
largely impregnated with salt, which is dreaded by the manufacturer even
more than albuminous impurities, and nearly as much as excess of potash
salts.
If the land is in good condition, containing sufficient available
nitrogen to meet the requirements of the crop, neither guano nor sulphate
of ammonia should be used. They largely increase the weight of the
produce per acre; but heavy crops are generally poor in sugar, and
furnish a juice that presents much difficulty to the manufacturer. If the
land is very poor, and if farmyard manure cannot be obtained and be
applied in autumn, 336 to 448 lbs. of Peruvian guano, or 224 lbs. of
sulphate of ammonia, mixed with 224 lbs. of superphosphate of lime, per
acre, may be sown broadcast in autumn, and 224 lbs. more of
superphosphate may be drilled in with the seed in spring. Superphosphate
of lime and bones are excellent for sugar-beets, and never injure the
quality of the crop, like the indiscriminate use of ammoniacal manures.
On light soils, in which potash is often deficient, the judicious use of
potash salts has been found serviceable, but only in conjunction with
superphosphate and phosphatic guanos.
=Sowing.= The best time for sowing beetroot is the beginning or middle of
April. If sown too early, the young plants may be partially injured by
frost; if later than the first week in May, the crop may require to be
taken up in autumn, before it has had time to get ripe. About 10 to 12
lbs. of seed is required per acre. As regards the width between the
plants, generally speaking, the distance between the rows and from plant
to plant should not be less than 12 nor greater than 18 in. Should the
young plants be caught by a night's frost, and suffer ever so little, it
is best to plough them up at once and re-sow, for they are certain to run
to seed, and are then practically useless for the manufacture of sugar.
Sugar-beets require to be frequently horse- and hand-hoed. As long as the
young plants are not injured, the application of the hoe from time to
time is attended with great benefit to the crop. It is advisable to
gather up the soil round each plant, in order that the head may be
completely covered with soil. Champonnois' researches point to the
advantage of planting in ridges, by which the supply of air to the roots
is greatly facilitated.
The conditions best calculated to ensure the roots possessing the
characters most desirable from a sugar-maker's point of view are chiefly
as follows: (1) Not to sow on freshly-manured land; it is eminently
preferable not to manure for the beet crop, but to manure heavily for
wheat in the preceding year; (2) not to employ forcing manures, nor to
apply manure during growth; (3) to use seed from a variety rich in sugar;
(4) to sow early, in lines 16 in. apart, at most, the plants being 10 to
11 in. from each other; there will then be 38,000 beets on an acre,
weighing 21 to 28 ounces each, or 52,800 to 70,400 lbs. per acre; (5) to
weed the fields as soon as the plants are above ground, to thin out as
early as possible, and to weed and hoe often, till the soil is covered
with the leaves of the plants; (6) never to remove the leaves during
growth; (7) finally, not to take up the roots, if it can be avoided,
before they are ripe, the period of which will depend upon the season.
Good seed may be raised by the following means: The best roots, which
show least above ground, are taken up, replanted in good soil, and
allowed to run to seed. This seed is already good; but it may be further
improved by sowing it in a well-prepared plot possessing all the most
favorable conditions; the resulting plants are sorted, set out in autumn,
put into a cellar, and in the spring, before transplanting, those of the
greatest density, and which will give seeds of the best quality, are
separated. These are transplanted at 20 in. between the rows and 13 in.
between the feet, which are covered with about 1-1/2 in. of earth.
Finally they are watered with water containing molasses and
superphosphate of lime, as recommended by Corenwinder.
=Harvesting.= Sugar-beets must be taken up before frost sets in. When the
leaves begin to turn yellow and flabby, they have arrived at maturity,
and the crop should be watched, that it may not get over-ripe. If the
autumn is cold and dry, the crop may be safely left in the ground for
seven to ten days longer than is needful, but should the autumn be mild
and wet, if the roots are left in the soil, they are apt to throw up
fresh leaves, and nothing does so much injury. In watching the ripening
of the crop, a good plan is to test the sp. gr. of the expressed juice. A
root or two may be taken up at intervals, and reduced to pulp on an
ordinary hand-grater, the juice obtained by pressing the pulp through
calico, and the density observed by a hydrometer. As long as the gravity
of the juice continues to increase, the crop should be left in the land.
Good sugar-yielding juice has a sp. gr. of about 1.065, rising to about
1.070. Immature roots, cut across, rapidly change color on the exposed
surface, turning red, then brown, and finally almost black. If newly-cut
slices turn color on exposure, the ripening is not complete; but if they
remain some time unaltered, or turn only slightly reddish, they are
sufficiently ripe to be taken up. The crop should be harvested in fine,
dry weather. In order that the roots may part with as much moisture as
possible, they are left exposed to the air on the ground before being
stacked, but not for longer than a few days, and they need to be guarded
against direct sunlight. Perhaps the best plan is to cover them loosely
with their tops in the field for a couple of days, then trim them, and at
once stack them.
=Storing.= For storing roots, especial care should be taken to prevent
their germinating and throwing out fresh tops, which is best done by
selecting a dry place for the storage ground. They may be piled in
pyramidal stacks, about six feet broad at base, and seven feet high. At
first, the stacks should be thinly covered with earth, that the moisture
may readily evaporate; subsequently, when frosty weather sets in, another
layer of earth, not exceeding one foot in thickness, may be added. This
is essentially the method generally adopted for storing potatoes and
beets.
[Illustration: FIG. 46.--Stack for Storing Beets.]
In continental Europe and Canada, extra precaution is necessitated by the
rigorous climate. In S. Russia, the plan shown in Fig. 46 is sometimes
used. The beets are disposed completely below the surface of the soil, in
a trench dug with sharply sloping sides. At about 15 in. from the bottom,
is an openwork floor of reeds, on which the beets are piled to within a
few inches of the level of the exterior soil. On the top, and following
the apex of the heap, is laid a triangular ridge-piece _a_, for the
purpose of facilitating evaporation. The whole is covered with a layer
_b_ of straw and fine earth, the thickness of which is varied according
to the indications of the thermometer _c_ placed in the center of the
mass. Between the floor of the trench and the openwork floor is a space
_d_, communicating with two vertical channels leading to the outer air,
thus providing ventilation. The outlets of the channels can be opened and
closed at will. The Russians also often employ regular cellars, as shown
in Fig. 47. The structure consists of two stories, covered with a bed of
earth, each furnished with a floor of hurdles or open planking, on which
the beets are piled to the depth of about one yard. Lateral passages
facilitate ventilation, and openings in the roof permit the heated air to
escape. The cost of erecting these cellars is heavy, but there is great
saving of labor in storing the beets, as it suffices to simply pile them
up on the floors. Moreover, the arrangement permits the examination of
the contents beyond the indications of a thermometer; and enables any
portion to be removed, even during snowy weather.
[Illustration: FIG. 47.--Storage Cellar for Beets.]
=Alcohol from Beets.= Beets contain 85 per cent. of water, and about 10
per cent. of cane sugar, the remainder being woody fibre and albumen;
cane sugar not being in itself fermentible,--as is grape sugar,--it has
to be converted into "inverted sugar" by a ferment as yeast. Either the
sugar beets may be mashed or the molasses which remains from the
manufacture of beet sugar (as described in Chapter X). The conversion of
the sugar into alcohol is effected in several different ways, of which
the following are the principal:
By rasping the roots and submitting them to pressure, and fermenting the
expressed juice.
By maceration with water and heat.
By direct distillation of the roots.
The first two methods are the best as by them the woody fibre of the
plant which is non-fermentible is separated from the fermentible juice.
In both the first and second processes the beets must first be entirely
cleaned of adhering dirt, trash and clods of earth, and then rasped,
pulped or sliced by certain machinery.
=Cleaning.= Care must be taken in this operation that the beets shall be
freed from small stones and adhering hard lumps of earth which would
otherwise get into the rasping machinery to the damage and stoppage of
the mechanism.
There are many forms of cleaners but all are alike in this,--that the
beets shall be subjected to the action of water while traveling through
or over a perforated casing. The simplest machine, and one easily
constructed by any carpenter, comprises an elongated cylinder formed of
lathes or strips spaced apart such distance as will allow dirt and stones
to pass between them. This is mounted on a central shaft and revolves in
a tank of water. It should be slightly inclined so that the potatoes or
beets to be washed may feed downward from the open upper end-disk or
wheel, to the lower end where they are thrown out. At the upper end is a
hopper and at the lower, the end disk has inwardly projecting lips, which
as the cylinder revolves lifts the beets up and tumbles them out on to an
incline which carries them to the rasping machine.
Another form of machine comprises a perforated cylinder of sheet iron,
revolving in a tank of water. A better form of cleaner than either of
those consists of an inclined trough in which a spiral feeding screw of
sheet iron rotates. The beets are fed into the trough at its lower end
and are carried upward, slowly, by the feeding screw. Above the trough is
a water pipe having a number of outlets by which water may fall on to the
beets and into the trough. The water rushing down the inclined trough
carries with it all dirt and stones, and by the time the beets have
reached the upper end they are entirely cleaned and ready for slicing or
rasping.
For pressing out the juice, the beets are mashed into a pulp, while for
diffusion the beets are sliced.
=Rasping.= Fig. 48 shows one form of rasping machine. On a suitable
supporting frame is mounted a cylinder _a_ having a diameter of about 24
inches. The cylinder is formed of alternate saw blades and wooden washers
holding them a slight distance apart. The saws or teeth are so set on the
cylinder as not to slice the beets but to shred them up into a fine pulp.
The cylinder rotates at a speed of 800 to 1000 revolutions a minute in
front of an inclined table, having a jigger whereby the beets are fed
downward against the toothed cylinder. The teeth carry the pulp downward
and it falls into a receptacle beneath.
[Illustration: FIG. 48.--Beet and Potato Rasp.]
It is best to add to this pulp a small portion of sulphuric acid, say
two-tenths of one per cent. This prevents by-fermentations.
=Pressing.= The pulp obtained from the raspers has now to be expressed.
This is either done by platen presses or by roller presses. With platen
presses the first pressing may be done by screws, but the final pressing
should be accomplished by hydraulic presses.
For the hydraulic press, the pulp is placed in woolen sacks, containing
10 to 12 lbs., superposed in the press with their mouths doubled under,
and separated by iron plates; about 25 are collected, and the pile is put
into a screw-press, called a "preparatory" press, which extracts about 45
to 50 per cent. of the juice. These pressed sacks are piled anew on the
movable plate of a powerful hydraulic press, which takes 50 at a charge.
Each preparatory press can supply four hydraulic presses, which are
ranged around it, so that of the four presses, there will be one
charging, one commencing to press, one in full pressure, and one
discharging, at the same moment. Motion is communicated to the four
hydraulic presses by four pumps mounted on the same bed, and tended by
the same workman who directs the pressing. An improvement upon the
general form of hydraulic press is that devised by Lalouette, which
enables two workmen and one boy to work five presses. These presses turn
out about 34,200 lbs. per 24 hours in the first pressing, and 68,400 lbs.
in the second. Hydraulic presses are rapidly falling into disuse in the
beet-sugar industry, by reason of the superior merits of continuous
presses, and the extended adoption of the diffusion system.
Continuous presses for beet were suggested by the roller-mills used in
the cane-sugar industry. But the conditions in the two cases are widely
different; the begass of the cane is solid, and readily parts from the
juice; whereas the pulp and juice of the beet have a strong tendency to
combine, and the roller-surface must therefore be permeable only by the
juice. In Poizot et Druelle's press, the pulp passes between two
cylinders, carried by endless cloths. The object is to unite the best
features of the hydraulic press. To this end, a first gentle pressing is
produced against the first cylinder by the elasticity of the principal
cloth on which it is borne. Then, encountering a series of four little
rollers, performing the functions of the preparatory press, it is next
seized between the second and first cylinders, and deprived of the
maximum quantity of juice.
[Illustration: FIG. 49.--Dujardin's Roll Press.]
Dujardin's roll press is shown in Fig. 49, which is a vertical section of
the machine, the side plate being removed. The pulp is forced upward
through a pipe _C_ under high pressure. This has a regulating slide valve
_D_. The rolls _B B_ revolve towards and nearly in contact with each
other, and they are perforated so that the expressed juice may run off
through the rolls. These perforations are conical in form with the apex
of the cone outward. The cylinders are also covered with a webbing of
cloth or horse hair. Below the rolls is block _C¥_, which with the outer
walls of the chamber, form diverging passages which extend upward, as
shown, on either side of the rolls and then downward along the lower
faces of the rolls to the point when they contact. The pulp is compressed
with great force against and between the rolls, the juice is forced
through the perforations and the residue passes upward and outward under
the presser bar _E_ in the form of a ribbon which is guided away by the
trough _F_. The pressure of the bar _E_ is regulated by screws and the
tighter said bar is pressed against the rolls the greater will be the
pressure of the pulp behind the bar and against the rolls, and the
greater the juice expressed.
The rolls revolve very slowly only about seven or eight times a minute
but the capacity of the machine is very great, it being capable of
pressing the pulp of from 85,000 to 175,000 lbs. of beets daily. The
residue from the first pressing should be submitted to a further pressing
after being macerated with spent wash. This residue may be fed to cattle.
The utmost cleanliness is essential to these processes; all the utensils
employed should be washed daily with lime-water to counteract acidity.
=Extraction by Maceration and Diffusion.= The object of this process is
to extract from the beets by means of water or spent liquor all the sugar
which they contain, without the aid of rasping or pressure. Spirit is
thus produced at considerably less expense, although it is not of so high
a quality as that yielded by the former process. The operation consists
in slicing up the beets in a specially constructed slicing machine, into
slices of regular thickness, and then allowing the slices to macerate in
a series of vats at stated temperatures. It is essential that the knives
by which the roots are cut should be so arranged that the roots are
divided into slices having a width of 4/10 of an inch and a thickness of
4/100 of an inch, and a variable length; the roots are, of course, well
washed before being placed in the hopper of the cutter.
When cut, the beets are covered with boiling water in a macerator of wood
or iron for one hour, the water should contain 4.4 of sulphuric acid to
every 2200 lbs. of beets. After this, the water is drawn off into a
second vat in which are placed more beets, and allowed to macerate again
for an hour. This is repeated a third time in another vat, and the juice,
which has now acquired a density equal to that obtained by rasping, is
run off into the fermenting vat. When the first vat is empty it is
immediately refilled with boiling water and fresh beets; the juice from
this operation is run into the second vat, when the contents of that one
are run into the third. To continue the operation, the beets are
completely exhausted by being macerated for an hour with a third charge
of boiling water (acidulated as in the former case). The exhausted pulp
is removed to make room for fresh slices; and the first vat is then
charged with juice which has already passed through the second and third
vats. After macerating the fresh beets for one hour, the charge is ready
for fermentation. In ordinary weather, the juice should now be at the
right heat for this process, viz., about 71.1∞ or 75.2∞ F., but in very
cold weather it may require some re-heating.
In Fig. 50 is shown a series of vats for the extraction of the sugar from
beets such as is termed a "diffusion battery."
[Illustration: FIG. 50.--Diffusion Battery.]
The vessels, 1, 2, 3 and 4 are of wood or sheet iron. Each vessel has a
bottom sieve and a top sieve between which the beet slices are to be
placed. From the bottom of each vessel below the sieve a pipe _D_ runs to
the top of the vessel next in order. From the bottom of the last vessel 4
of the series a pipe _C_ runs back to the top of the one first used.
Pipes _A_ and _B_ are connected to each vessel for the admission of water
and spent wash respectively. A discharge pipe _E_ leads from each vessel
to a collecting vat 5.
Maceration and diffusion is accomplished as follows: The sliced beets are
placed between the sieves in vessel 1 and water or spent wash at a
temperature of 185∞ F. is let in and the beets allowed to macerate for
three-quarters of an hour, meanwhile tub 2 is charged with sliced beets.
The cock or pipe _D_ between the vessels is opened when the time, three
quarters of an hour, has elapsed; hot water or spent wash is admitted by
pipes _A_ or _B_ to the vessel 1, which forces the sugar solution therein
into vessel 2. When the required amount of fluid has been passed into 2
from 1, the inlet of water into 1 is stopped, and the vessel heated to
185∞ F.
Vessel 3 is charged with beet slices and in three-quarters of an hour
vessels 1, 2 and 3 are connected and water or wash admitted into 1, which
forces the solution in 1 into 2 and that in 2 into 3 when it is again
raised to 185∞ F.
The same operation is repeated as to vessel 4 and in three-quarters of an
hour all the vessels are connected, hot water or spent wash is admitted
to 1 and the sugar solution drawn off from 4 into the vat.
The beets in tub 1 having now been exhausted, the fluid in that vessel is
drawn off and the exhausted beets thrown away. 1 is now recharged with
beets and the pipe between it and 4 opened. The former operation is
repeated except that now vessel 4 becomes 1, and 1 becomes 4. These
successive chargings and dischargings are continued; vessel 3 becomes 1
in its turn and so on.
=Fermentation.= Before fermentation the juice procured as has been
described is brought to about 82∞ F.; at this temperature it is run off
into the fermenting vats. Here it is necessary, as before noted, to add
to the juice a small quantity of concentrated sulphuric acid, for the
purpose of neutralizing the alkaline salts which it contains, and of
rendering it slightly acid in order to hasten the process; this quantity
must not exceed 5-1/2 lbs. to every 1220 gallons of juice, or the
establishment of fermentation would be hindered instead of promoted. The
addition of this acid tends also to prevent the viscous fermentation
to which the juice obtained by rasping and pressure is so liable.
Although the beet contains albumen, which is in itself a ferment, it
is necessary, in order to develop the process, to have recourse to
artificial means. A small quantity of brewer's yeast--about 1-3/4
oz. per 22 gallons of juice--is sufficient for this; the yeast must
previously be mixed with a little water. An external temperature of
about 68∞ to 78∞ F. must be carefully maintained. Fermentation lasts for
from four to five hours.
The fermentation of acidulated beet-juice sets in speedily. The chief
obstacle to the process is the mass of thick scum which forms upon the
surface of the liquor. This difficulty is sometimes obviated by using
several vats and mixing the juice, while in full fermentation, with a
fresh quantity. Thus, when three vats are employed, one is set to
ferment; at the end of four or six hours, half its contents are run into
the second vat and here mixed with fresh juice. The process is arrested,
but soon starts again in both vats simultaneously; the first is now
allowed to ferment completely, which is effected with much less
difficulty than would have been the case had the vat not been divided.
Meanwhile the second vat, as soon as the action is at its height, is
divided in the same manner, one-half its contents being run into the
third. When this method is employed, it is necessary to add a little
yeast from time to time when the action becomes sluggish.
=Direct Distillation of the Roots.= This process, commonly called
"Leplay's method," consists in fermenting the sugar in the slices
themselves. The operation is conducted in huge vats, holding as large a
quantity of matter as possible, in order that the fermentation may be
established more easily. They usually contain about 750 gallons, and a
single charge consists of 2200 lbs. of the sliced roots. The slices are
placed in porous bags in the vats, containing already about 440 gallons
of water acidulated with a little sulphuric acid; and they are kept
submerged by means of a perforated cover, which permits the passage of
the liquor and of the carbonic acid evolved; the temperature of the
mixture should be maintained at about 77∞ or 80∞ F. A little yeast is
added, and fermentation speedily sets in; it is complete in about 24
hours or more, when the bags are taken out and replaced by fresh ones;
fermentation declares itself again almost immediately, and without any
addition of yeast. New bags may, indeed, be placed in the same liquor for
three or four successive fermentations without adding further yeast or
juice.
The slices of beets charged with alcohol are now placed in a distilling
apparatus of a very simple nature. It consists of a cylindrical column of
wood or iron, fitted with a tight cover, which is connected with a coil
or worm, kept cool in a vessel of cold water. Inside this column are
arranged a row of perforated diaphragms or partitions. The space between
the lowest one and the bottom of the cylinder is kept empty to receive
the condensed water formed by the steam, which is blown into the bottom
of the cylinder in order to heat the contents. Vapors of alcohol are thus
disengaged from the undermost slices, and these vapors as they rise
through the cylinder vaporize the remaining alcohol, and finally pass out
of the top at a considerable strength and are condensed in the worm. When
all the contents of the still have been completely exhausted of spirit,
the remainder consists of a cooked pulp, which contains all the nutritive
constituents of the beet except the sugar.
CHAPTER X.
ALCOHOL FROM MOLASSES AND SUGAR CANE.
Another common source of alcohol is molasses. Molasses is the
uncrystallizable syrup which constitutes the residiuum of the manufacture
and refining of cane and beet sugar. It is a dense, viscous liquid,
varying in color from light yellow to almost black, according to the
source from which it is obtained; it tests usually about 40∞ by Baume's
hydrometer. The molasses employed as a source of alcohol must be
carefully chosen; the lightest in color is the best, containing most
uncrystallized sugar. The manufacture is extensively carried on in
France, where the molasses from the beet sugar refineries is chiefly used
on account of its low price, that obtained from the cane sugar factories
being considerably dearer. The latter is, however, much to be preferred
to the former variety as it contains more sugar. Molasses from the beet
sugar refineries yields a larger quantity and better quality of spirit
than that which comes from the factories. Molasses contains about 50 per
cent. of saccharine matter, 24 per cent. of other organic matter, and
about 10 per cent. of inorganic salts, chiefly of potash. It is thus a
substance rich in matters favorable to fermentation. When the density of
molasses has been lowered by dilution with water, fermentation sets in
rapidly, more especially if it has been previously rendered acid. As,
however, molasses from beet generally exhibits an alkaline reaction, it
is found necessary to acidify it after dilution; for this purpose
sulphuric acid is employed, in the proportion of about 4-1/2 lbs. of
the concentrated acid to 22 gallons of molasses, previously diluted
with eight or ten volumes of water. Three processes are thus employed
in obtaining alcohol from molasses; dilution, acidification, and
fermentation. The latter is hastened by the addition of a natural
ferment, such as brewer's yeast. It begins in about eight or ten hours,
and lasts upwards of 60.
About three gallons of Alcohol may be obtained from one hundred pounds of
molasses.
=Beet Sugar Molasses.= The first step in the process of rendering the
molasses fermentable is to mix the molasses with water, to a certain
dilution, in the proportion of two parts of water to one of molasses.
This may be done by hand, but preferably it is performed in a vat
provided with stirring or agitating mechanism, such as will effectually
mix the water with the viscid syrup, and whereby also the wash may be
thoroughly agitated and aerated.
There are numerous forms of mixing vats, all working however, on the
principle shown in Fig. 51. In this, the vat _A_ is provided with a
central shaft _C_ carrying radial mixing blades _E_. This shaft is
driven by bevel gears _D_, _F_. As the rotation of these blades would
merely tend to create a rotary current of molasses and water, and not to
mix them, some means should be used for impeding and breaking up this
current. To that end the cover is provided with downwardly projecting
rods _I_ which create counter currents, and thoroughly intermingle the
two liquids. Another and even better form of mixer consists of a tank
into the lower portion of which enters a perforated pipe of relatively
large diameter. This is provided at the end with an air entrance and a
steam injector. The injected steam draws in air and the steam and air are
forced under pressure into the vat, thus diluting the contained molasses,
agitating it and thoroughly aerating it.
[Illustration: FIG. 51.--Mixing Vat.]
The molasses as it comes from the sugar house may contain anywhere from
30 to 45 per cent of sugar, and this should be diluted with water to a
concentration of 16 to 18 per cent of sugar.
The density of the wash after "setting up" is 1.060. It is to be noted
that though with improved apparatus a wash as concentrated at 12∞ or 15∞
Baume may be worked; yet where simple apparatus is used six degrees or
eight degrees is better and much more favorable to rapid and complete
fermentation.
After setting up, one gallon of strong sulphuric acid and 10 lbs. of
sulphate of ammonia are added for each 1000 gallons of wash. This
neutralizes the alkaline carbonates in the beet juice which would
otherwise retard fermentation, and it assists the yeast to invert the
cane sugar as formerly described. The addition of ammonia is in order to
give food to the yeast and obtain a vigorous fermentation.
The yeast used for fermenting molasses is prepared either from malt or
grain and is used as concentrated as possible, and in the proportion of
about 2 per cent.
The "pitching" temperature of a molasses wash varies with the
concentration of the wash, being higher for strongly concentrated
solutions than for weak ones. When the wash tests as high as 12∞ Baume,
fermentation begins at about 77∞ F. and is raised during fermentation to
85∞ or 90∞ F. A temperature around 82∞ F. is best on the average as this
is most conducive to the growth of yeast.
Where the vats are large and the syrup considerably diluted the
temperature rises very quickly and must be moderated by passing a current
of cold water through a coil of pipe on the bottom of the vat.
In the making of molasses mashes it must be remembered that every gallon
of molasses will be diluted with about five gallons of water or other
fermented liquid matter, and therefore 50 gallons of molasses wash will
require a still capable of working up about 300 gallons. It is possible
to distill four or five charges during the day of 12 hours and hence a
still of 60 gallons will be capable of distilling the beer or wash made
with 50 gallons of molasses. A still with a capacity of 100 gallons
operating on wash having a strength of one gallon of molasses to five of
water, will produce about 10 gallons of proof spirit from each charge;
thus a 100 gallon still will make from 40 to 80 gallons of spirit in a
day. With unskilled labor, however, it is impossible to get this rate of
production and the best that can be done will be about four charges a
day.
It may be suggested that in getting estimates on stills it is best to
accompany the request with a statement of the character of the mash
intended to be treated, the amount of raw materials intended to be used
up, the charging capacity required, number of gallons of mash desired to
be worked up every 12 hours.
=Fermenting Raw Sugar.= This is accomplished by dissolving the sugar in
hot water, then diluting it, and then adding a ferment,--fermentation
being aided by adding sulphuric acid to the diluted molasses, in the
proportion of one-half to one pound of acid to every hundred pounds of
pure sugar used.
The wash is pitched with compressed yeast in the proportion of 2-1/2[**
fraction] to 8 per cent of the weight of the sugar used. The pitching
temperature is from 77∞ to 79∞ F., and the period of fermentation is 48
hours.
=Cane Sugar Molasses.= Besides the molasses of the French beet sugar
refineries, large quantities result from the manufacture of cane sugar in
Jamaica and the West Indies. This is entirely employed for the
distillation of _rum_. As the pure spirit of Jamaica is never made from
sugar, but always from molasses and skimmings, it is advisable to notice
these two products, and, together with them, the exhausted wash commonly
called _dunder_.
The molasses proceeding from the West Indian cane sugar contains
crystallizable and uncrystallizable sugar, gluten, or albumen, and other
organic matters which have escaped separation during the process of
defecation and evaporation, together with saline matters and water. It
therefore contains in itself all the elements necessary for fermentation,
_i.e._, sugar, water, and gluten, which latter substance, acting the part
of a ferment, speedily establishes the process under certain conditions.
_Skimmings_ comprise the matters separated from the cane juice during
the processes of defecation and evaporation. The scum of the clarifiers,
precipitators, and evaporators, and the precipitates in both clarifiers
and precipitators, together with a proportion of cane sugar mixed with
the various scums and precipitates, and the "sweet-liquor" resulting from
the washing of the boiling-pans, etc., all become mixed together in the
skimming-receiver and are fermented under the name of "skimmings." They
also contain the elements necessary for fermentation, and accordingly
they very rapidly pass into a state of fermentation when left to
themselves; but, in consequence of the glutinous matters being in excess
of the sugar, this latter is speedily decomposed, and the second, or
acetous fermentation, commences very frequently before the first is far
advanced. _Dunder_ is the fermented wash after it has undergone
distillation, by which it has been deprived of the alcohol it contained.
To be good, it should be light, clear, and slightly bitter; it should be
quite free from acidity, and is always best when fresh. As it is
discharged from the still, it runs into receivers placed on a lower
level, from which it is pumped up when cool into the upper receivers,
where it clarifies, and is then drawn down into the fermenting cisterns
as required. Well-clarified dunder will keep for six weeks without any
injury. Good dunder may be considered to be the liquor, or "wash," as it
is termed, deprived by distillation of its alcohol, and much concentrated
by the boiling it has been subjected to; whereby the substances it
contains, as gluten, gum, oils, etc., have become, from repeated
boilings, so concentrated as to render the liquid mass a highly aromatic
compound. In this state it contains at least two of the elements
necessary for fermentation, so that, on the addition of the third, viz.,
sugar, that process speedily commences.
The first operation is to clarify the mixture of molasses and skimmings
previous to fermenting it. This is performed in a leaden receiver holding
about 300 or 400 gallons. When the clarification is complete, the clear
liquor is run into the fermenting vat, and there mixed with 100 or 200
gallons of water (hot, if possible), and well stirred. The mixture is
then left to ferment. The great object that the distiller has in view in
conducting the fermentation is to obtain the largest possible amount of
spirit that the sugar employed will yield, and to take care that the loss
by evaporation or acetification is reduced to a minimum. In order to
ensure this, the following course should be adopted. The room in which
the process is carried on must be kept as cool as it is possible in a
tropical climate; say, 75∞ to 80∞ F.
Supposing that the fermenting vat has a capacity of 1000 gallons, the
proportions of the different liquors run in would be 200 gallons of
well-clarified skimmings, 50 gallons of molasses, and 100 gallons of
clear dunder; they should be well mixed together. Fermentation speedily
sets in, and 50 more gallons of molasses are then to be added, together
with 200 gallons of water. When fermentation is thoroughly established, a
further 400 gallons of dunder may be run in, and the whole well stirred
up. Any scum thrown up during the process is immediately skimmed off. The
temperature of the mass rises gradually until about 4∞ or 5∞ above that
of the room itself. Should it rise too high, the next vat must be set up
with more dunder and less water; if it keeps very low, and the action is
sluggish, less must be used next time. No fermenting principle besides
the gluten contained in the wash is required. The process usually
occupies eight or ten days, but it may last much longer. The liquid now
becomes clear, and should be immediately subjected to distillation to
prevent acetous fermentation.
Sugar planters are accustomed to expect one gallon of proof rum for every
gallon of molasses employed. On the supposition that ordinary molasses
contains 65 parts of sugar, 32 parts of water, and three parts of organic
matter and salts, and that, by careful fermentation and distillation, 33
parts of absolute alcohol may be obtained, we may then reckon upon 33
lbs. of spirit, or about four gallons, which is a yield of about 5-2/3[**
fraction] gallons of rum, 30 per cent. over-proof, from 100 lbs. of such
molasses.
The following process is described in Deerr's work on "Sugar and Sugar
Cane."
"In Mauritius a more complicated process is used; a barrel of about 50
gallons capacity is partly filled with molasses and water of density 1.10
and allowed to spontaneously ferment; sometimes a handful of oats or rice
is placed in this preliminary fermentation. When attenuation is nearly
complete more molasses is added until the contents of the cask are again
of density 1.10 and again allowed to ferment. This process is repeated a
third time; the contents of the barrel are then distributed between three
or four tanks holding each about 500 gallons of wash of density 1.10 and
12 hours after fermentation has started here, one of these is used to
pitch a tank of about 8,000 gallons capacity; a few gallons are left in
the pitching tanks which are again filled up with wash of density 1.10
and the process repeated until the attenuations fall off, when a fresh
start is made. This process is very similar to what obtains in modern
distilleries save that the initial fermentation is adventitious.
"In Java and the East generally, a very different procedure is followed.
In the first place a material known as Java, or Chinese, yeast is
prepared from native formulÊ; in Java, pieces of sugar cane are crushed
along with certain aromatic herbs, amongst which galanga and garlic are
always present, and the resulting extract made into a paste with rice
meal; the paste is formed into strips, allowed to dry in the sun and then
macerated with water and lemon juice; the pulpy mass obtained after
standing for three days is separated from the water and made into small
balls, rolled in rice straw and allowed to dry; these balls are known as
Raggi or Java yeast. In the next step rice is boiled and spread out in a
layer on plantain leaves and sprinkled over with Raggi, then packed in
earthenware pots and left to stand for two days, at the end of which
period the rice is converted into a semi-liquid mass; this material is
termed Tapej and is used to excite fermentation in molasses wash. The
wash is set up at a density of 25∞ Balling and afterwards the process is
as usual. In this proceeding the starch in the rice is converted by means
of certain micro-organisms _Chlamydomucor oryzae_ into sugar and then
forms a suitable habitat for the reproduction of yeasts which are
probably present in the Raggi but may find their way into the Tapej from
other sources. About 100 lbs. of rice are used to pitch 1,000 gallons of
wash."
CHAPTER XI.
ALCOHOLOMETRY.
Alcoholmetry is the name given to a variety of methods of determining the
quantity of absolute alcohol contained in spirituous liquors. It will
readily be seen that a quick and accurate method of making such
determinations is of the very utmost importance to those who are engaged
in the liquor traffic, since the value of spirit depends entirely upon
the percentage of alcohol which it contains. When alcoholic liquors
consist of simple mixtures of alcohol and water, the test is a simple
one, the exact percentage being readily deducible from the specific
gravity of the liquor, because to a definite specific gravity belongs a
definite content of alcohol; this is obtained either by means of the
_specific gravity bottle_, or of hydrometers of various kinds, specially
constructed.
All hydrometers comprise essentially a graduated stem of uniform
diameter, a bulb forming a float and a counterpoise or ballast. The
hydrometers may either be provided with a scale indicated on the neck or
else with weights added to sink the hydrometer to a certain mark. The
first instruments are called hydrometers of "constant immersion," the
others, of "variable immersion."
At the latter end of the last century, a series of arduous experiments
were conducted by Sir C. Blagden, at the instance of the British
government, with a view to establishing a fixed proportion between the
specific gravity of spirituous liquors and the quantity of absolute
alcohol contained in them. The result of these experiments, after being
carefully verified, led to the construction of a series of tables,
reference to which gives at once the percentage of alcohol for any given
number of degrees registered by the hydrometer; these tables are
invariably sold with the instrument. They are also constructed to show
the number of degrees over-or under-proof, corresponding to the
hydrometric degrees. Other tables are obtainable which give the specific
gravity corresponding to these numbers.
The measurement of the percentage of absolute alcohol in spirituous
liquors is almost invariably expressed in volume rather than weight,
owing to the fact that such liquors are always sold by volume.
Nevertheless, the tables referred to above show the percentage of spirit
both by volume and weight.
[Illustration: FIG. 52.--Syke's Hydrometer.]
In the United States the standard liquor, known as _proof spirit_,
contains 92.3 per cent. by weight and 94.9 per cent. by volume, of
absolute alcohol; it has a specific gravity of .9186 at 60∞ F. A proof
gallon contains by measurement 100 parts of alcohol and 81.5 parts of
water. The strength and therefore the value of spirituous liquors is
estimated according to the quantity by volume of anhydrous spirit
contained in the liquor with reference to this standard. Thus the
expression "20 _per cent. overproof_," "20 _per cent. underproof_," means
that the liquor contain 20 volumes of water for every 100 volumes over
or under this fixed quantity, and that in order to reduce the spirit to
_proof_, 20 per cent. of water by volume, must be subtracted or added, as
the case may be. Any hydrometer constructed for the measurement of
liquids of less density than water may be employed. That known as
"Syke's" is most commonly used for alcoholometric purposes. It is shown
in Fig. 52 and consists of a spherical brass ball _A_, to which is fixed
two stems; the upper one _B_ is also of brass, flat, and about 3-1/2[**
fraction] in. in length; it is divided into ten parts, each being
subdivided into five, and the whole being numbered as shown in the
figure. The lower stem _C_ is conical, and slightly more than an inch
long; it terminates in a weighted bulb _D_. A series of circular weights,
of the form shown in the figure, accompany the instrument; these are
slipped upon the top of the lower stem _C_, and allowed to slip down
until they rest upon the bulb _D_. The instrument is used in the
following way: It is submerged in the liquor to be tested until the whole
of the upper stem is under the surface, and an idea is thus gained of the
weight that will be required to _partly_ submerge the stem. This weight
is added, and the hydrometer again placed in the liquor. The figure on
the scale to which the instrument has sunk when at rest is now observed,
and added to the number on the weight used, the sum giving, by reference
to the tables, the percentage by volume of absolute alcohol above or
below the standard quantity.
In exact estimations, the temperature of the liquor tested must be
carefully registered, and the necessary corrections made. In Jones's
hydrometer, which is an improvement upon Syke's, a small spirit
thermometer is attached to the bulb, and by noting the temperature of the
liquor at the time of the experiment, and referring to the tables
accompanying the instrument, the strength is found at once without the
need of calculation.
Dica's hydrometer is very similar to Jones's instrument above described.
It is of copper, has a stem fitted to receive brass poises, a
thermometer, a graduated scale, etc.
In Europe, Gay-Lussac's hydrometer and tables are chiefly used for
alcoholometric testing. This instrument is precisely similar in
construction to those of Twaddle and Baume. On the scale, zero is
obtained by placing it in pure distilled water at 59∞ F., and the highest
mark, or 100, by placing it in pure alcohol at the same temperature, the
intermediate space being divided into 100 equal divisions, each
representing one per cent. of absolute alcohol. The correction for
temperature, as in the above cases, is included in the reference tables.
Another hydrometer, used in France for alcoholometric determinations, is
Cartier's. In form it is precisely similar to Baume's hydrometer. Zero is
the same in both instruments, but the point marked 30∞ in Cartier's is
marked 32∞ in Baume's, the degrees of the latter being thus diminished in
the proportion of 15 or 16. Cartier's hydrometer is only used for liquids
lighter than water.
The alcoholmeter of Tralles is the official instrument for testing
alcoholic liquors in the U. S. but the instrument which is most generally
used both here and abroad is that of BeaumÈ. There are two instruments
bearing BeaumÈ's name, one for liquids lighter than water, the other for
those which are heavier. All hydrometers, alcoholmeters and
saccharometers work on the same principle, though they are each
differently graduated for the particular work to be done and the details
of the measuring process are slightly different. All these instruments
are provided with tables whereby their readings may be corrected and the
specific gravity of the liquid determined.
The above hydrometric methods can be safely employed only when the spirit
tested contains a very small amount of solid matter, since, when such
matter is contained in the liquor in quantity, the density alone cannot
possibly afford a correct indication of its richness in alcohol. Many
methods have been proposed for the estimation of alcohol in liquor,
containing saccharine coloring and extractive matters, either in solution
or suspension. Undoubtedly the most accurate of these, though at the same
time the most tedious, is to subject the liquor to a process of
distillation by which a mixture of pure alcohol and water is obtained as
the distillate. This mixture is carefully tested with the hydrometer, and
the percentage of alcohol in it determined by reference to the tables as
above described; from this quantity and the volume of the original liquor
employed the percentage by volume of alcohol in that liquor is readily
found. The condensing arrangement must be kept perfectly cool, if
possible in a refrigerator, as the alcohol in the distillate is very
liable to be lost by re-evaporation. When great accuracy is desired, and
time is at the operator's disposal, the above method is preferable to all
others.
It is performed in the following manner: Three hundred parts of the
liquor to be examined are placed in a small still, or retort, and exactly
one-third of this quantity is distilled over. A graduated glass tube is
used as the receiver, in order that the correct volume may be drawn over
without error. The alcoholic richness of the distillate is then
determined by any of the above methods, and the result is divided by
three, which gives at once the percentage of alcohol in the original
liquor. The strength at proof may be calculated from this in the ordinary
way.
If the liquor be acid, it must be neutralized with carbonate of soda
before being submitted to distillation. From eight to ten per cent. of
common salt must be added, in order to raise the boiling point, so that
the whole of the spirit may pass over before it has reached the required
measure. In the case of the stronger wines it is advisable to distil over
150 parts and divide by two instead of three. If the liquor be stronger
than 25 per cent. by volume of alcohol, or above 52 to 54 per cent.
under-proof, an equal volume of water should be added to the liquid in
the still, and a quantity distilled over equal to that of the sample
tested, when the alcoholic strength of the distillate gives, without
calculation, the correct strength required. If the liquor be stronger
than 48 to 50 per cent. under-proof, three times its volume of water must
be added, and the process must be continued until the volume of the
distillate is twice that of the sample originally taken. In each case the
proportionate quantity of common salt must be added.
For the estimation of alcohol in wines, liquors, etc., the following
method may be employed: A measuring flask is filled up to a mark on its
neck with the liquor under examination, which is then transferred to a
retort; the flask must be carefully rinsed out with distilled water, and
the rinsings added to the liquor in the retort. About two-thirds are then
drawn over into the same measuring flask, and made up to its previous
bulk with distilled water, at the same temperature as that of the sample
before distillation. The strength is then determined by means of Syke's
hydrometer, and this, if under-proof, deducted from 100, gives the true
percentage of proof-spirit in the wine.
[Illustration: FIG. 53.--Field's Alcoholometer.]