DE-NATURING REGULATIONS IN THE UNITED STATES.
The Free Alcohol Act of 1906, and proposed changes therein. The
Amendment of 1907. Internal Revenue Regulations. 224
Index. 261
LIST OF ILLUSTRATIONS
No. PAGE.
1 Vacuum mash cooker _to face_ 10
2 Henze steamer 12
3 Mash cooler, air system 15
4 Mash cooler, water system 17
5 Yeasting and fermenting apparatus _to face_ 22
6 A simple still 34
7 Simple direct-heated still 35
8 Simple still, with rectifier 37
9 Adam's still 39
10 Corty's simplified distilling apparatus 41
11 Double still 42
12 Dorn's compound still 43
13 Compound still 46
14 Compound direct-fire still 47
15 Cellier-Blumenthal still 49
16 Details of rectifier column 50
17 Details of condenser and mash heater 52
18 Coffey's rectifying still 55
19, 20 Rotary current still 59, 60
21 Indicator for regulating the distilling fire 61
22 Diagrammatic view of column still and accessory
apparatus _to face_ 64
23 Distilling plate 64
24, 25 Barbet traps 68
26 Steam regulator 70
27 Gauge glass for regulator 72
28 Continuous distilling apparatus with external tubular
condenser _to face_ 72
29 Detail of chamber, continuous still 73
30, 31 Details of perforated plate _A_ 75, 76
32 Continuous distilling apparatus with goose separator _to face_ 76
33 Section of Gillaume's inclined column still 78
34 Gillaume's inclined column still 79
35 Rectifying still 88
36 Section of rectifying still 89
37 Fractional distilling apparatus 91
38 Rectifying apparatus with external tubular condenser _to face_ 94
39 Twin column Barbet rectifier 95
40 Gillaume's rectifier and inclined still 97
41 Steaming vat for potatoes 112
42 Bottom of steaming vat 113
43 Steam generator 114
44 Potato steamer and crusher 116
45 Bohn's steamer and crusher 118
46 Stack for storing beets 148
47 Storage cellar for beets 149
48 Beet and potato rasp 152
49 Dujardin's roll press 155
50 Defusion battery 158
51 Mixing vat 165
52 Syke's hydrometer 176
53 Field's alcoholometer 182
54 Geisler's apparatus 184
55 Continuous grain alcohol distillery--Barbet's system 198
56 Grain distillery, capacity 2500 bushels per day _to face_ 198
57 Small beet distillery 200
58 Large beet distillery 202
59 Molasses distillery, capacity 2500 gallons per day _to face_ 206
60 Molasses fermenting house 207
CHAPTER I.
ALCOHOL, ITS VARIOUS FORMS AND SOURCES.
=Alcohol.= (Fr., _alcool_; Ger., _alkohol_.) Formula, C_{2}H_{6}O.
Pure alcohol is a liquid substance, composed of carbon, hydrogen, and
oxygen, in the following proportions:
C 52.17
H 13.04
O 34.79
------
100.00
It is the most important member of an important series of organic
compounds, all of which resemble each other closely, and possess many
analogous properties. They are classed by the chemist under the generic
title of "Alcohols."
Alcohol does not occur in nature; it is the product of the decomposition
of sugar, or, more properly, of _glucose_, which, under the influence of
certain organic, nitrogenous substances, called _ferments_ is split up
into alcohol and carbonic anhydride. The latter is evolved in the form of
gas, alcohol remaining behind mixed with water, from which it is
separated by distillation. The necessary purification is effected in a
variety of ways.
TABLE I.--THE BOILING POINTS OF ALCOHOLIC LIQUORS OF DIFFERENT
STRENGTHS, AND THE PROPORTIONS OF ALCOHOL IN THE VAPORS GIVEN OFF.
===========+===========+===========+===========+===========+===========
Proportion| |Proportion |Proportion | |Proportion
of alcohol|Temperature|of alcohol |of alcohol |Temperature|of alcohol
in the | of the |in the | in the | of the | in the
boiling | boiling |condensed | boiling | boiling |condensed
liquid in | liquid. |vapor in | liquid in | liquid. | vapor in
100 vols. | |100 vols. | 100 vols. | | 100 vols.
-----------+-----------+-----------+-----------+-----------+-----------
92 | 171.0 F. | 93 | 20 | 189.5 F. | 71
90 | 171.5 F. | 92 | 18 | 191.6 F. | 68
85 | 172.0 F. | 91.5 | 15 | 194.0 F. | 66
80 | 172.7 F. | 90.5 | 12 | 196.1 F. | 61
75 | 173.6 F. | 90 | 10 | 198.5 F. | 55
70 | 175.0 F. | 89 | 7 | 200.6 F. | 50
65 | 176.0 F. | 87 | 5 | 203.0 F. | 42
50 | 178.1 F. | 85 | 3 | 205.1 F. | 36
40 | 180.5 F. | 82 | 2 | 207.5 F. | 28
35 | 182.6 F. | 80 | 1 | 209.9 F. | 13
30 | 185.0 F. | 78 | 0 | 212.0 F. | 0
25 | 187.1 F. | 76 | | |
===========+===========+===========+===========+===========+===========
Pure, absolute alcohol is a colorless, mobile, very volatile liquid,
having a hot, burning taste, and a pungent and somewhat agreeable odor.
It is very inflammable, burning in the air with a bluish-yellow flame,
evolving much heat, leaving no residue, and forming vapors of carbonic
anhydride and water. Its specific gravity at 0∞ C (32∞ F.) is .8095, and
at 15.5∞ C. (60∞ F.) .794; that of its vapor is 1.613. It boils at 78.4∞
C. (173∞ F.). The boiling point of its aqueous mixtures are raised in
proportion to the quantity of water present. Mixtures of alcohol and
water when boiled give off at first a vapor rich in alcohol, and
containing but little aqueous vapor; if the ebullition be continued a
point is ultimately reached when all the alcohol has been driven off and
nothing but pure water remains. Thus, by repeated distillations alcohol
may be obtained from its mixtures with water in an almost anhydrous
state.
Absolute alcohol has a strong affinity for water. It absorbes moisture
from the air rapidly, and thereby becomes gradually weaker; it should
therefore be kept in tightly-stoppered bottles. When brought into contact
with animal tissues, it deprives them of the water necessary for their
constitution, and acts in this way as an energetic poison. Considerable
heat is disengaged when alcohol and water are brought together; if,
however, ice be substituted for water, heat is absorbed, owing to the
immediate and rapid conversion of the ice into the liquid state. When one
part of snow is mixed with two parts of alcohol, a temperature as low as
5.8∞ F. below zero is reached.
When alcohol and water are mixed together the resulting liquid occupies,
after agitation, a less volume than the sum of the two original liquids.
This contraction is greatest when the mixture is made in the proportion
of 52.3 volumes of alcohol and 47.7 volumes of water, the result being,
instead of 100 volumes, 96.35. A careful examination of the liquid when
it is being agitated reveals a vast number of minute air-bubbles, which
are discharged from every point of the mixture. This is due to the fact
that gases which are held in solution by the alcohol and water separately
are less soluble when the two are brought together; and the contraction
described above is the natural result of the disengagement of such
dissolved gases. The following table represents the contraction undergone
by different mixtures of absolute alcohol and water.
TABLE II.--100 VOLUMES OF MIXTURE AT 59∞ F.
========+============++========+============++========+============
Alcohol.|Contraction.||Alcohol.|Contraction.||Alcohol.|Contraction.
--------+------------++--------+------------++--------+------------
100 | 0.00 || 65 | 3.61 || 30 | 2.72
95 | 1.18 || 60 | 3.73 || 25 | 2.24
90 | 1.94 || 55 | 3.77 || 20 | 1.72
85 | 2.47 || 50 | 3.74 || 15 | 1.20
80 | 2.87 || 45 | 3.64 || 10 | 0.72
75 | 3.19 || 40 | 3.44 || 5 | 0.31
70 | 3.44 || 35 | 3.14 || |
========+============++========+============++========+============
Alcohol is termed "absolute" when it has been deprived of every trace of
water, and when its composition is exactly expressed by its chemical
formula. To obtain it in this state it must be subjected to a series of
delicate operations in the laboratory, which it would be impossible to
perform on an industrial scale. In commerce it is known only in a state
of greater or less dilution.
Alcohol possesses the power of dissolving a large number of substances
insoluble in water and acids, such as many inorganic salts, phosphorus,
sulphur, iodine, resins, essential oils, fats, coloring matters, etc. It
precipitates albumen, gelatine, starch, gum, and other substances from
their solutions. These properties render it an invaluable agent in the
hands of the chemist.
Alcohol is found in, and may be obtained from, all substances--vegetable
or other--which contain sugar. As stated above, it does not exist in
these in the natural state, but is the product of the decomposition by
fermentation of the saccharine principle contained therein; this
decomposition yields the spirit in a very dilute state, but it is readily
separated from the water with which it is mixed by processes of
distillation, which will subsequently be described. The amount of alcohol
which may be obtained from the different unfermented substances which
yield it varies considerably, depending entirely upon the quantity of
sugar which they contain.
Alcohol is produced either from raw materials containing starch, as
potatoes, corn, barley, etc., or raw materials containing sugar, as
grapes, beets, sugar-cane, etc.
The following are some of the most important sources from which alcohol
is obtained: Grapes, apricots, cherries, peaches, currents, gooseberries,
raspberries, strawberries, figs, plums, bananas, and many tropical
fruits, artichokes, potatoes, carrots, turnips, beet-root, sweet corn,
rice and other grains. Sugar-cane refuse, sorgum, molasses, wood, paper,
and by a new French process from acetylene. On a large scale alcohol is
usually obtained from sugar beets, molasses or the starch contained in
potatoes, corn and other grains. The starch is converted into maltose by
mixing with an infusion of malt. The maltose is then fermented by yeast.
Sulphuric acid may be used to convert even woody fibre, paper, linen,
etc., into glucose, which may in turn be converted into alcohol.
TABLE III.--PRINCIPAL ALCOHOLS.
=================+=======================+==============+==============
Chemical Name. | Source. | Formula. |Boiling Point
∞F.
-----------------+-----------------------+--------------+--------------
1 Methyl Alcohol|Distillation of Wood |CH_{3}OH | 150.8
2 Ethyl " |Fermentation of sugar |C_{2}H_{5}OH | 172.4
3 Propyl " | " " grapes |C_{3}H_{7}OH | 206.6
4 Butyl " | " " beets |C_{4}H_{9}OH | 242.6
5 Amyl " | " " potatoes|C_{5}H_{11}OH | 278.6
6 Caproyl " | " " grapes |C_{6}H_{13}OH | 314.6
7 Aenanthyl " |Distillation castor oil|C_{7}H_{15}OH | 347.
| with potatoes | |
8 Capryl " |Essential oil hog weed |C_{8}H_{17}OH | 375.8
9 Nonyl " |Nonane from petroleum |C_{9}H_{19}OH |
10 Rutyl " |Oil of Rue |C_{10}H_{21}OH|
11 Cytyl " |Spermaceti |C_{16}H_{33}OH|
12 Ceryl " |Chinese wax |C_{26}H_{53}OH|
13 Melisyl " |Bees' wax |C_{30}H_{61}OH|
=================+=======================+==============+==============
Among a variety of other substances which have been and are still used
for the production of alcohol in smaller quantities, are roots of many
kinds, such as those of asphodel, madder, etc. Seeds and nuts have been
made to yield it. It will thus be seen that the sources of this
substance are practically innumerable; anything, in fact, which contains
or can be converted into sugar is what is termed "alcoholisable."
Alcohol has become a substance of such prime necessity in the arts and
manufactures, and in one form or another enter so largely into the
composition of the common beverages consumed by all classes of people
that its manufacture must, of necessity, rank among the most important
industries of this and other lands.
Of the alcohols given in the above table only two concern the ordinary
distiller, or producer of alcohol for general use in the arts. Methyl
alcohol, the ordinary "wood alcohol," or wood naphtha, and Ethyl alcohol,
which is produced by the fermentation of sugar and may therefore be made
from anything which contains sugar.
Ethyl alcohol forms the subject of this treatise. Aside from its chemical
use in the arts as a source of energy and as a fuel, alcohol will likely
soon compete with petroleum, gasoline, kerosene, etc., under the Act of
Congress freeing the "de-naturized" spirit from the Internal Revenue tax.
This act and the de-naturing process are covered in the last chapters of
this book.
CHAPTER II.
THE PREPARATION OF MASHES, AND FERMENTATION.
Alcohol may be produced either from, (1) farinacious materials, such as
potatoes or grains, (2), from sacchariferous substances such as grapes,
sugar beets, sugar cane, or the molasses produced in sugar manufacture.
THE PREPARATION OF STARCHY MATERIALS.
=Saccharification.= =Preparatory Mashing.= With starchy materials it is
first necessary to convert the starch into a sugar from which alcohol can
be produced by the process of fermentation. This is called
saccharification.
=Gelatinizing.= The first step in this process is gelatinizing the
starch;--that is, forming it into a paste by heating it with water, or
into a liquid mass by steaming it under high pressure. The liquid or
semi-liquid mass is then run into a preparatory mash vat and cooled.
=Saccharifying.= The disintegrated raw materials or gelatinized starch in
the preparatory mash vat is now to be "saccharified" or converted into
sugar. This is effected by allowing malt to act on the starch. This malt
contains a certain chemical "ferment" or enzyme, called "diastase" ("I
separate").
This is able under proper conditions to break up the gelatinized starch
into simpler substances--the dextrins--and later into a fermentable sugar
called maltose.
=Fermentation.=--The maltose or sugar in the "mash" is now to be
converted into alcohol. This is accomplished by fermentation, a process
of decomposition which converts the sugar into carbonic acid and alcohol.
Fermentation is started by yeast, a fungus growth, which in the course of
its life history produces a matter called zymose which chemically acts on
the sugar to split it up into carbonic acid gas and alcohol.
Yeast may be either "wild" or cultivated. If the mash is left to stand
under proper condition the wild yeast spores in the air, will soon settle
in the mash and begin to multiply. This method of fermentation is bad
because other organisms than yeast will also be developed,--organisms
antagonistic to proper fermentation. As a consequence, pure or cultivated
yeast is alone used.
This yeast is cultivated from a mother bed in a special yeast mash and
when ripened is mixed with the mash in the fermenting vat. At a
temperature between 50∞ F. and 86∞ F. the yeast induces fermentation,
converting the sugar of the mash into carbon dioxid which escapes, and
alcohol which remains in the decomposed mash, or "beer" as it is termed
in the United States.
It now remains to separate the alcohol from the water of the beer with
which it is mixed. This is accomplished by distillation and
rectification, as will be fully described in the chapters following.
PRODUCTION OF ALCOHOL FROM SACCHARIFEROUS SUBSTANCES.
Substances such as grape juice, fruit juice, sugar beets, cane sugar and
molasses already contain fermentable sugar. Saccharification is therefore
not needed and juices or liquids from these matters are either directly
fermented as in the case of sugar cane, or--as in the case of sugar
beets--the sugar in juice is transferred by yeast into a fermentable
sugar.
MASHING STARCHY MATERIALS.
We will now consider in more detail the preparation of mashes from
starch-containing substances.
=Gelatinizing Apparatus.= These comprise either ordinary vats, into which
steam at low pressure is admitted (see Fig. 44), cookers and stirrers
such as shown in Fig. 1 and 45 or the Henze steamer (Fig. 2.)
[Illustration: FIG. 1.--Vacuum Mash Cooker. (_To face page 10_)]
An example of a cooking and mashing apparatus and its connections is
shown in Fig. 1. This is the vacuum cooker put on the market by the
Vulcan Copper Works Company, of Cincinnati, Ohio. This consists of a
cylindrical steel vessel the interior of which is fitted with stirrer
arms attached to a shaft making about sixty revolutions per minute. The
steam enters the vessel at the bottom by means of pipes conducting it
from a manifold, or header, in the same manner as is shown in the
apparatus illustrated in Fig. 45. Attached to each pipe at its point of
entrance is a check valve to spray the steam through the mash. A
thermometer for registering the temperature and a water gauge are placed
in the manifold. The grain enters the cooker from the grain hopper by way
of a spout. The cylinder has been previously supplied with hot water and
during the mixing of the meal with the hot water the mass is constantly
stirred. The malt is mixed with water in the small grain tub which is
provided with a stirrer. The malt mash is admitted into the cooker and
the mass thoroughly mixed by the arms. After the mashing, the product
passes off to the drop tub and from thence to the mash coolers where it
is cooled to the proper temperature for fermentation. The gearing for
agitating the malt mash and the grain or potato mash is evident from the
drawing.
The pressure steamers used in mashing are shown in Fig. 2. They comprise
a cylindrical vessel preferably conical or partly conical, provided with
steam entrance pipes, air valves and a manhole. At the bottom of the cone
forming the lower end of the steamer is a grating located in an exit
pipe provided with a valve. One of the steam entrance pipes is so located
that the steam is forced in at the top of the cylinder while the other
allows steam to enter at the bottom of the cylinder. The device is
provided with a pressure gauge and an air cock.
[Illustration: FIG. 2.--Henze Steamer.]
In use the body of the apparatus is partly filled with water and the
material to be treated. This is acted upon by a steam pressure of two
atmospheres, which is later increased to three, steam entering by the
lowermost pipe, passing up through the water and potatoes thoroughly
agitating the same and passing away by the steam gauge. After standing at
the last pressure for ten or fifteen minutes the lower steam inlet is
closed; the upper inlet and the blow-out valve are opened. The steam is
then increased to its highest point or about four atmospheres and the
lower valve is opened. The disintegrated material is forced out by the
steam through the grating at the bottom of the cone. This comminutes it
and pulps it before it passes into the preparatory mash tub. Blowing out
requires about 40 to 50 minutes. Steaming and blowing out together cover
a space of two hours. The pressure of the steam before blowing out should
be such that the steam is constantly being blown off through the safety
valve. Thus the mass in the steamer is agitated and the material entirely
disintegrated and gelatinized.
=Process.= Into these apparatuses the potatoes and corn or grain first
ground into mash, or even corn or grain unground, if the pressure is high
enough, are disintegrated and cooked by steam under high pressure. During
this process the starch becomes partially dissolved and partially
gelatinized, which occurs when a pressure of some 65 pounds has been
attained, with a temperature of about 300∞ F.
=Saccharifying.= It is now necessary to saccharify the gelatinized mass.
This is accomplished by adding to it a certain amount of malt, whereby
maltose or sugar is formed through the action of the diastase. The amount
of maltose so created is in proportion to the amount of malt used, the
length of time it is acting, the dilution of the mash, and the existence
of a proper temperature. The temperature best fitted for this action lies
above 122∞ F., but in order to entirely dissolve the starch a temperature
of 145∞ F. should be used. In addition, at this higher temperature, the
bacteria inimical to fermentation are destroyed. A higher temperature
than 145∞ F. should not be allowed, except in extraordinary cases as it
injures the effectiveness of the diastase.
=Apparatus.= The mixture of the malt with the mash may either take place
in the heater and cooker itself (see Fig. 2) or in a preparatory mash
vat.
In the first instance, the malt is allowed to enter the cooking cylinder
when the temperature of the mash is about 145∞ F. The mash is stirred
until thoroughly mixed when the product is drawn into a receptacle called
a drop tub and later reduced to a proper fermenting temperature.
When the Henze type of steamer is used, the pulped mass (see Page 121) is
blown into a preparatory mash vat, at the proper temperature. It is left
to stand at this temperature for a period varying from twenty minutes to
an hour and a half.
=Cooling the Mash.= Saccharification takes place at a temperature above
122∞ F., but the proper fermenting temperature is only about 63∞ F. to
68∞ F., and hence some means must be adopted for cooling the hot mash to
this temperature and for so cooling it in a relatively short time.
[Illustration: FIG. 3.--Mash Cooler, Air System.]
=Cooling= may be accomplished by submitting the mash to currents of air;
to contact with cold water coils or by the use of ice. One of the
simplest coolers of the first class is shown in Fig. 3.
This consists of a shallow panlike tank A having means for introducing
and drawing off the mash. Rotating in the center of the tank is a
vertical shaft _C_ carrying radiating stirrer arms _B_. Braces _M_
extend to the middle of these arms and the arms carry a number of blades
or paddles _b_, which extend down into the mash. Above the arms, mounted
loosely on the same shaft, but rotating in the opposite direction, are
fans _H_ supported by arms _J_ which create air currents over the
agitated mash. These fans move at a much faster rate than the stirrers
_B_.
A simple form of driving gear is shown. The main shaft _C_ is rotated by
a large bevel gear _D_, meshing with a small pinion _E_ on the end of a
driving shaft _F_, which is driven by a belt. This shaft also carries a
bevel gear _L_, which meshes with a bevel gear _K_ mounted on a sleeve.
This sleeve surrounds and rotates freely on the central shaft _C_, being
supported at its lower end in ball bearings _m m_, mounted on the shaft.
This combination gives opposite rotation to the faces and stirrer arms
and at different speeds. The driving mechanism can be of course varied.
Another simple method of air cooling would be to let the mash run down a
series of enclosed steps or chutes, the casing being kept cool by an air
blast. Mashes may be even cooled by mere stirring by paddles, but this
takes a long time and much labor.
The preparatory mash vats used to-day are almost all provided with
stirrers formed of hollow blades capable of a rapid stirring movement
through the mash. Through the hollow blades cold water is forced. Mash
vats of this kind should have the following qualities. They should be
strongly built, particularly as regards the stirrers so as to be used
with thick mashes. They should thoroughly and uniformly stir and mix the
mash and they should be capable of cooling the mash within an hour, and
should be so constructed as to be easily cleaned.
By using coils of pipe which may be inserted or withdrawn from the mash
tub, and through which cold water is forced, the mash may be effectively
cooled, but the best plan for quick cooling is to bring a comparatively
thin layer of the mash in contact with the coils. This may be
conveniently done by using a system of comparatively large water pipes
enclosing small pipes for the passage of the mash.
[Illustration: FIG. 4.--Mash Cooler, Water System.]
This should be arranged in a stand like the coils of a radiator with an
incline from the inlet end of the top pipe to the outlet end of the
lowermost pipe. As stated, the small pipe carries the mash, the large
pipe the water.
Preferably the mash flows downward while the water is forced upward in a
contrary direction by means of a pump or a high level reservoir. The
cooled mash should flow into the fermenting tank at a temperature of
about 68∞ F.
There are many varieties of mash cooling apparatuses on the market of
more or less complication suited to the needs of large and expensive
plants.
The form of cooler best to be used depends upon the circumstances of each
case and whether thick or thin mashes are to be distilled. The cooler
should, however, be capable of thorough cleansing so that no portion of
one mashing be carried to another.
=Fermentation= is an obscure and seemingly spontaneous change or
decomposition which takes place in most vegetable and animal substances
when exposed at ordinary temperatures to air and moisture. While
fermentation broadly covers decay or putrifaction, yet it is limited in
ordinary use to the process for producing alcoholic liquors from
sacchariferous mashes.
Fermentation is brought about by certain bodies called ferments--these
are either organized, as vegetable ferments such as yeast, or unorganized
as diastase--the enzyme of germinated malt. The last is used to convert
starch into maltose, the first is used to convert maltose into
fermentable sugar. The organized ferments are either to be found floating
freely in the air under the name of wild yeast or are artificially
produced. If a solution of pure sugar be allowed to stand so that it can
be acted on by the organisms in the air, it will remain unaltered for a
long time, but finally mold will appear upon it and it will become sour
and dark-colored. If, however, a suitable ferment is added to it, such as
yeast, it rapidly passes into a state of active fermentation by which the
sugar is split up into alcohol and carbon dioxid, the process continuing
from 48 hours to several weeks according to the temperature, the amount
of sugar present, and the nature and quantity of the ferment.
Fermentation cannot occur at a temperature much below 40∞ F., nor above
140∞ F. The limits of practical temperature, however, are 41∞ to 86∞ F.
Brewer's yeast is chiefly employed in spirit manufacture.
The most striking phenomena of fermentation are the turbidity of the
liquid, the rising of gas bubbles to the surface, and the increase in
temperature, the disappearance of the sugar, the appearance of alcohol
and the clearing of the liquid. At the end a slight scum is formed on the
top of the liquid and a light colored deposit at the bottom. This deposit
consists of yeast which is capable of exciting the vinous fermentation in
other solutions of sugar. The lower the temperature the slower the
process, while at a temperature above 86∞ F. the vinous fermentation is
liable to pass into other forms of fermentation to be hereafter
considered.
There are many theories of fermentation, of which the two most important
are those of Pasteur and Buchner. The first teaches that fermentation is
caused purely by the organic life of the yeast plant and is not a mere
chemical action, whereas the second view most largely held to-day is that
fermentation is a purely chemical change due to certain unorganized
substances called "enzymes" present in the yeast.
The theory need not detain us. It is sufficient that the yeast plant in
some manner acts to decompose the saccharified mash into alcohol and
carbonic acid gas.
=Yeast= is a fungus, a mono-cellular organism, which under proper
conditions propogates itself to an enormous extent. There are many races
or varieties of yeast each having its peculiar method of growth.
For our purposes we may divide the yeast races into two classes, wild
yeast and cultivated yeast. Originally any of the yeast races were
supposed to be good enough to effect fermentation but to-day every effort
is made to procure and use only those races which have the greatest power
to decompose sugar. It was for this reason that the old distiller kept
portions of his yeast over from one fermentation to the next. This was
yeast whose action they understood and whose abilities were proven. This
yeast so kept was open, however, to the chance of contamination and yeast
to-day is as carefully selected and bred as is a strain of horses, or
dogs, or plants.
After getting a portion of selected pure yeast for breeding purposes, it
may be sowed, that is, propagated very carefully in a yeast mash, in
sterilizing apparatus, where all chance of contamination by bacteria or
wild yeast is avoided. From this bed of mother yeast, or start yeast, the
yeast for the successive yeast mashes is taken.
The preparation of the various varieties of yeast mashes is too lengthy
to be set forth except in special treatises on the subject, but the
ordinary method of yeasting is as follows, reference being made to Fig.
5, which shows the apparatus used in the yeasting and fermenting
departments of a distillery, as installed by the Vulcan Copper Works, of
Cincinnati. The yeast tubs are shown to the left of the illustration.
They are each provided with cooling coils and stirrers.
The yeast mash we will assume is composed of equal parts of barley malt
and rye meal. Hot water at 166∞ F. is first put into the mash tub. The
rake or stirrers are then rotated and the meal run in slowly. The
stirring is continued for twenty minutes after the meal is all in, during
which the mash has become saccharified.
The mash is then allowed to stand for about twenty hours, and to grow
sour by lactic fermentation. The lactic acid so produced protects the
mother yeast from infection by suppressing wild yeast and bacteria.
During this period great care is taken to prevent the temperature of the
mash falling below 95∞ F. and consequent butyric and acetous fermentation
following. After it has so stood the sour mash is cooled by circulating
water in the coils and stirring until it is reduced to from 59∞ to 68∞ F.
depending on whether the mash is thin or thick. Start yeast during the
cooling of the mash when at above 86∞ F. is added and stirred in. For the
next twelve hours the yeast ferments and when a temperature of 84∞ F. has
been attained the mash is cooled to 65∞ F. at which temperature it is
maintained until allowed to enter the fermenting tubs through the pipe
leading thereto from the yeast tub.
There are four principal kinds of fermentation: alcoholic, acetous,
lactic and viscous.
=Alcoholic Fermentation.= This may be briefly described as follows: The
mash in the fermenting vat having been brought to the proper temperature,
the ferment is thrown in, and the whole is well stirred together.
This is known as pitching.
[Illustration: FIG. 5.--Yeasting and Fermenting Apparatus.
(_To face page 22_)]
The proper pitching temperature varies with the method of fermentation
adopted, the length of the fermenting period, the materials of the mash,
its thickness or attenuation. It must always be remembered that there is
a great increase in the temperature of the "beer" during fermentation and
that the temperature at its highest should never under any circumstances,
become greater than 86∞ F. and with thick mashes that even a less heat is
desirable. Therefore the pitching temperature should be such that the
inevitable rise due to fermentation shall not carry the temperature to or
beyond the maximum point desired for the particular mash being
treated. It is to accurately control the pitching temperature and the
fermenting temperature that the fermenting tanks are provided with
cooling appliances.
In about three hours' time, the commencement of the fermentation is
announced by small bubbles of gas which appear on the surface of the vat,
and collect around the edges. As these increase in number, the whole
contents are gradually thrown into a state of motion, resembling violent
ebullition, by the tumultuous disengagement of carbonic anhydride. The
liquor rises in temperature and becomes covered with froth. At this
point, the vat must be covered tightly, the excess of gas finding an exit
through holes in the lid; care must now be taken to prevent the
temperature from rising too high, and also to prevent the action from
becoming too energetic, thereby causing the contents of the vat to
overflow. In about twenty-four hours the action begins to subside, and
the temperature falls to that of the surrounding atmosphere. An hour or
two later, the process is complete; the bubbles disappear, and the
liquor, which now possesses the characteristic odor and taste of alcohol,
settles out perfectly clear. The whole operation, as here described,
usually occupies from forty-eight to seventy-two hours. The duration of
the process is influenced, of course, by many circumstances, chiefly by
bulk of the liquor, its richness in sugar, the quality of the ferment,
and the temperature.
=Acetous Fermentation.= This perplexing occurrence cannot be too
carefully guarded against. It results when the fermenting liquor is
exposed to the air. When this is the case, the liquor absorbs a portion
of the oxygen, which unites with the alcohol, thus converting it into
acetic acid as rapidly as it is formed. When acetous fermentation begins,
the liquor becomes turbid, and a long, stringy substance appears, which
after a time settles down to the bottom of the vat. It is then found that
all the alcohol has been decomposed, and that an equivalent quantity of
acetous acid remains instead. It has been discovered that the presence of
a ferment and a temperature of 68∞ to 95∞ F. are indispensable to acetous
fermentation, as well as contact with the atmosphere. Hence, in order to
prevent its occurrence, it is necessary not only to exclude the air, but
also to guard against too high a temperature and the use of too much
ferment. The latter invariably tends to excite acetous fermentation. It
should also be remarked that it is well to cleanse the vats and utensils
carefully with lime water before using, in order to neutralize any acid
which they may contain; for the least trace of acid in the vat has a
tendency to accelerate the conversion of alcohol into vinegar. A variety
of other circumstances are favorable to acetification, such as the use of
a stagnant or impure water, and the foul odors which arise from the vats;
stormy weather or thunder will also engender it.
=Lactic Fermentation.= Under the influence of lactic fermentation, sugar
and starch are converted into lactic acid. When it has once begun, it
develops rapidly, and soon decomposes a large quantity of glucose; but as
it can proceed only in a neutral liquor, the presence of the acid itself
speedily checks its own formation. Then, however, another ferment is
liable to act upon the lactic acid already formed, converting it into
_butyric acid_, which is easily recognized by its odor of rank butter.
Carbonic anhydride and hydrogen are evolved by this reaction. The latter
gas acts powerfully upon glucose, converting it into a species of gum
called _mannite_, so that lactic fermentation--in itself an intolerable
nuisance--becomes the source of a new and equally objectionable waste of
sugar. It can be avoided only by keeping the vats thoroughly clean; they
should be washed with water acidulated with five per cent of sulphuric
acid. An altered ferment, or the use of too small a quantity, will tend
to bring it about.
The best preventives are _thorough cleanliness_, and the use of good,
fresh yeast in the correct proportion.
=Viscous Fermentation.= This is usually the result of allowing the vats
to stand too long before fermentation begins. It is characterized by the
formation of viscous or mucilaginous matters, which render the liquor
turbid, and by the evolution of carbonic anhydride and hydrogen gases the
latter acting as in the case of lactic fermentation and converting the
glucose into mannite. Viscous fermentation may generally be attributed to
the too feeble action of the ferment. It occurs principally in the
fermentation of white wines, beer, and beet-juice, or of other liquors
containing much nitrogenous matter. It may be avoided by the same
precautions as are indicated for the prevention of lactic fermentation.
=Periods of Fermentation.= The operation of fermentation may be
conveniently divided into three equal periods.
The first or pre-fermentation period is that when the yeast mixed into
the mash is growing; the temperature should then be kept at about 63 to
68∞ F. during which time the yeast is propagated. The growth of the yeast
is manifested by the development of carbonic acid gas and by a slight
motion of the mash. When alcohol is produced to an extent of say five per
cent. the growth of the yeast stops.
The second period of chief fermentation then begins. Carbonic acid is
freely developed and the sugar is converted into alcohol. The temperature
at this time should not exceed 81.5∞ F. The second period of fermentation
continues about 12 hours, when the last period commences.
During the third period or after fermentation there is a lessening of the
formation of carbonic acid and a lowering of the temperature. In this
stage the mash is kept at a temperature of 77∞ to 81∞ F.
In order to conveniently regulate the temperature of the mash the vat may
be provided with a copper worm at the bottom thereof, through which cold
water is forced. This, however, need only be used for thick mashes. There
are also various kinds of movable coolers used for this purpose.
There are a number of different forms which fermentation may take. The
insoluble constituents of the mash in the process of fermentation are
forced to the surface, and form what may be termed a cover. If the
carbonic acid gas bubbles seldom break this cover it indicates that the
conversion of the sugar into alcohol and carbonic acid is proceeding very
slowly and imperfectly. If, however, the cover is swirling and seething,
and particularly if the cover is rising and falling with every now and
then a discharge of gas, it is an indication that the conversion is
properly proceeding. Foaming of the mash is to be prevented, as the froth
or foam flows over the mash tank and considerable loss is sustained. It
may be prevented by pouring a little hot lard into the vat, or petroleum,
provided its odor will not interfere with the use of the alcohol when
distilled.
Water is added in small quantities near the termination of the second
period of fermentation. This dilutes the alcohol, in the mash and lessens
its percentage, and thus the further growth of the yeast is permitted.
After fermentation the mash takes either the form of a thick diluted pulp
or of a thin liquor. Again the reader is reminded that the mash after
fermentation contains alcohol mixed with water--and that the next step in
the process--distillation is necessary merely to separate the alcohol
from the water.
There is always some loss in the process of fermentation; in other words,
the actual production is below the theoretical amount due. Theoretically
one pound of starch should yield 11.45 fluid ounces of alcohol. With a
good result 88.3 per cent. of this theoretical yield is obtained; with an
average result of 80.2 per cent. and with a bad result only about 72.6
per cent. or less.
=Fermenting Apparatus.= It remains now to describe briefly the vessels or
vats employed in the processes of fermentation. They are made of oak or
cypress, firmly bound together with iron bands, and they should be
somewhat deeper than wide, and slightly conical, so as to present as
small a surface as possible to the action of the air. Their dimensions
vary, of course, with the nature and quantity of the liquor to be
fermented. Circular vats are preferable to square ones, as being better
adapted to retain the heat of their contents. The lid should close
securely, and a portion of it should be made to open without uncovering
the whole. For the purpose of heating or cooling the contents when
necessary, it is of great advantage to have a copper coil at the bottom
of the vat, connected with two pipes, one supplying steam and the other
cold water.
=Iron vats= have also been used, having a jacketed space around them,
into which hot or cold water may be introduced. As wooden vats are porous
and hence uncleanly they have to be constantly scrubbed and disinfected.
It is advisable to cover the interior with linseed oil, varnish or with a
shellac varnish. The diameter of the coil varies according to the size of
the vat.
=The room= in which the vats are placed should be made as free from
draughts as possible by dispensing with superfluous doors and windows; it
should not be too high and should be enclosed by thick walls in order to
keep in the heat. As uniformity of temperature is highly desirable, a
thermometer should be kept in the room, and there should be stoves for
supplying heat in case it be required. The temperature should be kept
between 64∞ F. and 68∞ F.
Every precaution must be taken to ensure the most absolute cleanliness;
the floors should be swept or washed with water daily, and the vats, as
pointed out above, must be cleaned out as soon as the contents are
removed. For washing the vats, lime-water should be used when the
fermentation has been too energetic or has shown a tendency to become
acid; water acidulated with sulphuric acid is used when the action has
been feeble and the fermented liquor contains a small quantity of
undecomposed sugar. Care must be taken to get rid of carbonic anhydride
formed during the operation. Buckets of lime-water are sometimes placed
about the room for the purpose of absorbing this gas; but the best way of
getting rid of it is to have a number of holes, three or four inches
square, in the floor, through which the gas escapes by reason of its
weight. The dangerous action of this gas and its effects upon animal life
when unmixed with air are too well know to necessitate any further
enforcement of these precautions.
=The beer= obtained by mashing and fermenting consist essentially of
volatile substances, such as water, alcohol, essential oils and a little
acetic acid, and of non-volatile substances, such as cellulose, dextrine,
unaltered sugar and starch, mineral matters, lactic acid, etc.
=The volatile constituents= of the liquor possess widely different
degrees of volatility; the alcohol has the lowest boiling point, water
the next, then acetic acid, and last the essential oils. It will thus be
seen that the separation of the volatile and non-volatile constituents by
evaporation and condensation of the vapors given off is very easily
effected, and that also by the same process, which is termed
_distillation_, the volatile substances may be separated from one
another. As the acetic acid and essential oils are present only in very
small quantities, they will not require much consideration.
The aim of distillation is to separate as completely as possible the
alcohol from the water which dilutes it. Table I shows the amount of
alcohol contained in the vapors given off from alcoholic liquids of
different strength, and also their boiling points.
A glance at this table shows to what an extent an alcoholic liquor may be
strengthened by distillation, and how the quantity of spirit in the
distillate increases in proportion as that contained in the original
liquor diminishes. It will also be seen that successive distillations of
spirituous liquors will ultimately yield a spirit of very high strength.
As an example, suppose that a liquid containing five per cent, of alcohol
is to be distilled. Its vapor condensed gives a distillate containing 42
per cent. of alcohol which, if re-distilled, affords another containing
82 per cent. This, subjected again to distillation, yields alcohol of
over 90 per cent. in strength. Thus three successive distillations have
strengthened the liquor from five per cent. to 90 per cent.
It will thus be clear that the richness in alcohol of the vapors given
off from boiling alcoholic liquids is not a constant quantity, but that
it necessarily diminishes as the ebullition is continued. For example a
liquor containing seven per cent. of alcohol yields, on boiling a vapor
containing 50 per cent. The first portion of the distillate will,
therefore, be of this strength. But as the vapor is proportionally richer
in alcohol, the boiling liquor must become gradually weaker, and, in
consequence, must yield weaker vapors. Thus, when the proportion of
alcohol in the boiling liquid has sunk to five per cent., the vapors
condensed at that time will contain only 40 per cent.; at two per cent.
of alcohol in the liquor, the vapors yield only 28 per cent., and at one
per cent., they will be found when condensed to contain only 13 per cent.
From this it will be understood that if the distillation be stopped at
any given point before the complete volatilization of all the alcohol the
distillate obtained will be considerably stronger than if the process had
been carried on to the end. Moreover, another advantage derived from
checking the process before the end, and keeping the last portions of the
distillate separate from the rest, besides that of obtaining a stronger
spirit, is that a much purer one is obtained also. The volatile,
essential oils, mentioned above, are soluble only in strong alcohol, and
insoluble in its aqueous solutions. They distill also at a much higher
temperature than alcohol, and so are found only among the last products
of the distillation, which results from raising the temperature of the
boiling liquid. This system of checking the distillation and removing the
products at different points is frequently employed in the practice of
rectification.
CHAPTER III.
DISTILLING APPARATUS.
=The Apparatus= employed in the process of distillation is called a
_still_, and is of almost infinite variety. A still may be any vessel
which will hold and permit fermentated "wash" or "beer" to be boiled
therein, and which will collect the vapors arising from the surface of
the boiling liquid and transmit them to a condenser. The still may be
either heated by the direct application of fire, or the liquid in the
still raised to the boiling point by the injection of steam. The steam or
vapor rising from the boiling liquid must be cooled and condensed. This
is done by leading it into tubes surrounded by cold water or the "cold
mash."
The very simplest form of still is shown in Fig. 6, and consists of two
essential parts, the still, or boiler _A_, made of tinned copper, the
condenser _C_ which may be made of metal or wood and the worm _B_ made of
a coil of tinned copper pipe.
The liquor is boiled in _A_ and the vapors pass off into the worm _B_,
which is surrounded by the cold water of the condenser, the distillate
being drawn off at _f_.
The heated vapors passing through the worm _B_ will soon heat up the
water in _C_ thereby retarding perfect condensation. To prevent this, a
cold water supply pipe may be connected to the bottom of _C_ making a
connection at the top of _C_ for an over flow of the warmed up water. By
this means the lowest part of the worm will be kept sufficiently cool to
make a rapid condensation of the vapors.
[Illustration: FIG. 6.--A Simple Still.]
The boiler _A_ can be made in two parts; the upper part fitting into the
lower part snugly at _d_. The pipe from the upper part fitting the worm
snugly at _e_. This will enable the operator to thoroughly cleanse the
boiler before putting in a new lot of liquor. The joints at _e_ and _d_
should be luted with dough formed by mixing the flour with a small
portion of salt and moistening with water. This is thoroughly packed at
the junctions of the parts to prevent the escape of steam or vapor.
Fig. 7 shows such a Still as manufactured by the Geo. L. Squier Mfg. Co.,
Buffalo, N. Y.
[Illustration: FIG. 7.--Simple Direct-Heated Still.]
In an apparatus of this kind, the vapors of alcohol and water are
condensed together. But if instead of filling the condenser _C_ with cold
water, it is kept at a temperature of 176∞ F. the greater part of the
water-vapor will be condensed while the alcohol, which boils at 172.4∞ F.
passes through the coil uncondensed. If therefore the water be condensed
and collected separately in this manner, and the alcoholic vapors be
conducted into another cooler kept at temperature below 172.4∞ F., the
alcohol will be obtained in a much higher state of concentration than it
would be by a process of simple distillation.
Supposing, again, that vapors containing but a small quantity of alcohol
are brought into contact with an alcoholic liquid of lower temperature
than the vapors themselves, and in very small quantity, the vapor of
water will be partly condensed, so that the remainder will be richer in
alcohol than it was previously. But the water, in condensing, converts
into vapor a portion of the spirit contained in the liquid interposed, so
that the uncondensed vapors passing away are still further enriched by
this means. Here, then, are the results obtained; the alcoholic vapors
are strengthened, firstly, by the removal of a portion of the water
wherewith they were mixed; and then by the admixture with them of the
vaporized spirit placed in the condenser. By the employment of some such
method as this, a very satisfactory yield of spirit may be obtained, both
with regard to quality, as it is extremely concentrated, and to the cost
of production, since the simple condensation of the water is made use of
to convert the spirit into vapor without the necessity of having recourse
to fuel. The construction of every variety of distilling apparatus now in
use is based upon the above principles.
A sectional view of another simple form of still is shown in Fig. 8; _V_
is a wooden vat having a tight fitting cover _a_, through the center of
which a hole has been cut. The wide end of a goose neck of copper pipe
_g_ is securely fitted over this aperture, the smaller end of this pipe
passes through the cover of the retort _R_ extending nearly to the
bottom; _f_ is the steam supply pipe from boiler; _M_ the rectifier
consisting of a cylindrical copper vessel containing a number of small
vertical pipes surrounded by a cold water jacket; _o_ the inlet for the
cold water which circulates around these small pipes, discharging at _n_;
the pipes in _M_ have a common connection to a pipe _p_, which connects
the rectifier with coil in cooler _C_; _s_ is a pipe to the receptacle
for receiving the distillate; _u_ cold water supply pipe to cooler, and
_W_ discharge for warmed-up water, _k_ discharge for refuse wash in vat
_V_.
[Illustration: FIG. 8.--Simple Still, with Rectifier.]
The operation is as follows: The vat _V_ is nearly filled with fermented
mash and retort _R_ with weak distillate from a previous operation. Steam
is then turned into the pipe _f_ discharging near the bottom of the vat
_V_ and working up through the mash. This heats up the mash and the
vapors escape up _g_ over into _R_ where they warm up the weak
distillate. The vapors thus enriched rise into _M_, where a good
percentage of the water vapor is distilled, that is, condensed by the
cold water surrounding the small pipes. The vapor then passes over
through _p_ into the coil, where it is liquified and from whence it
passes by pipe _s_ into the receiver. The cold water for cooling both _M_
and _C_ can be turned on as soon as the apparatus has become thoroughly
heated up.
The stills in use to-day in many parts of the South for the production of
whiskey are quite as simple as those above described, and some for the
making of "moonshine" liquor are more so.
The first distilling apparatus for the production of strong alcohol on an
industrial scale was invented by Edward Adam, in the year 1801. The
arrangement is shown in Fig. 9, in which _A_ is a still to contain the
liquor placed over a suitable heater. The vapors were conducted by a tube
into the egg-shaped vessel _B_, the tube reaching nearly to the bottom;
they then passed out by another tube into a second egg _C_; then, in some
cases, into a third, not shown in the figure, and finally into the worm
_D_, and through a cock at _G_ into the receiver. The liquor condensed in
the first egg is stronger than that in the still, while that found in the
second and third is stronger than either. The spirit which is condensed
at the bottom of the worm is of a very high degree of strength. At the
bottom of each of the eggs, there is a tube connected with the still, by
which the concentrated liquors may be run back into _A_ for
redistillation after the refuse liquor from the first distill has been
run off.
[Illustration: FIG. 9.--Adam's Still.]
In the tube is a stop-cock _a_, by regulating which, enough liquor could
be kept in the eggs to cover the lower ends of the entrance pipes, so
that the alcoholic vapors were not only deprived of water by the cooling
which they underwent in passing through the eggs, but were also mixed
with fresh spirit obtained from the vaporization of the liquid remaining
in the bottom of the eggs, in the manner already described.
Adam's arrangement fulfilled, therefore, the two conditions necessary for
the production of strong spirit inexpensively; but unfortunately it had
also serious defects. The temperature of the egg could not be maintained
at a constant standard, and the bubbling of the vapors through the liquor
inside created too high a pressure. It was, however, a source of great
profit to its inventor for a long period, although it gave rise to many
imitations and improvements.
The operation of distilling is often carried on in the apparatus
represented in Fig. 22. It is termed the Patent Simplified Distilling
Apparatus; it was originally invented by Corty, but it has since
undergone much improvement. _A_ is the body of the still, into which the
wash is put; _B_ the head of the still; _c c c_ three copper plates
fitted in the upper part of the three boxes; these are kept cool by a
supply of water from the pipe _E_, which is distributed on the top of the
boxes by means of the pipes _G G G_. The least pure portion of the
ascending vapors is condensed as it reaches the lowest plate, and falls
back, and the next portion as it reaches the second plate, while the
purest and lightest vapors pass over the goose-neck, and are condensed in
the worm. The temperature of the plates is regulated by altering the flow
of water by means of the cock _F_. For the purpose of cleaning the
apparatus, a jet of steam or water may be introduced at _a_. A regulator
is affixed at the screw-joint _H_, at the lower end of the worm, which
addition is considered an important part of the improvement. The part of
the apparatus marked _I_ becomes filled soon after the operation has
commenced; the end of the other pipe _K_ is immersed in water in the
vessel _L_. The advantage claimed for this apparatus is that the
condensation proceeds in a partial vacuum, and that there is therefore a
great saving in fuel. One of these stills, having a capacity of 400
gallons, is said to work off four or five charges during a day of 12
hours, furnishing a spirit 35 per cent. over-proof.
[Illustration: FIG. 10.--Corty's Simplified Distilling Apparatus.]
Fig. 11 represents a double still which was at one time largely employed
in the colonies. It is simply an addition of the common still _A_ to the
patent still _B_. From time to time the contents of _B_ are run off into
_A_, those of _A_ being drawn off as dunder, the spirit from _A_ passing
over into _B_. Both stills are heated by the same fire; and it is said
that much fine spirit can be obtained by their use at the expense of a
very inconsiderable amount of fuel.
[Illustration: FIG. 11.--Double Still.]
=Compound Distillation.= Where stills of the form shown in Figs. 6 and 8
are used the alcohol obtained is weak. Hence it is necessary that the
distillate be again itself distilled, the operation being repeated a
number of times. In the better class of still, however, compound
distillation is performed the mash is heated by the hot vapors rising
from the still and the vapors are condensed and run back into the still
greatly enriched.
[Illustration: FIG. 12.--Dorn's Compound Still.]
The principle of compound distillation is well shown in Dorn's apparatus,
Fig. 12. This consists of a still or boiler _A_ having a large
dome-shaped head, on the interior faces of which the alcoholic vapors
will condense. Thus only enriched vapors will pass up through goose-neck
_B_ to the mash heater _D_. _C_ is a worm the end of which passes out to
a compartment _E_ through an inclined partition _F_. From the compartment
_E_ a pipe _e_ leads into the still _A_. An agitator _H_ is used for
stirring the mash, so that it may be uniformly heated. A pipe _d_
provided with a cock allows the mash to be drawn off into the still _A_.
From the highest point of the compartment _E_ a pipe _M_ leads to
condensing coil _K_ in a tub _J_ of cold water, having a draw-off cock
_I_.
At the exit end of the condensing worm _K_ the tube is bent in a U form
as at _L_, one arm of which has a curved open-ended continuation _n_,
through which the air in the worm is expelled. The other arm opens into
an inverted jar _l_ containing a hydrometer, for indicating the strength
of the spirit. The spirits pass off through _m_ into a receiver.
In operation the mash is admitted into the heater _D_ through _G_ until
the heating tank is nearly filled. A certain amount of mash is then
allowed to run into the still _A_ through the pipe _d_. The cock in _d_
is closed and the fire lighted.
The vapors from the still are condensed in worm _C_ and the condensed
liquid drops down into compartment _E_. Any vapor passing through _B_ and
_C_ so highly heated as to be uncondensed in coils _C_ passes through
the layer of liquid in compartment _E_, collects in the highest portion
of the compartment and passes through pipe _M_ to coil _K_ where it is
entirely liquefied. If the liquid in _E_ rises beyond a certain level it
passes through pipe _e_ back to the still. Any vapors which may collect
in the upper part of _D_ pass into the small bent pipe opening into the
first coil of worm _C_. Water for rinsing the heater _D_ may be drawn
through cock _s_ from the tub _J_ and warm water for rinsing the still,
through pipe _d_ from the heater.
Another form of compound still is shown in Fig. 13. In this the still _S_
is divided into an upper and lower compartment by a concavo-convex
partition _d_, having at its crown an upwardly extending tube _t_ from
which projects side tubes _p_. A pipe _P_ opens above and extends from
tube _t_. _C_ is the mash heater and condenser. Connected to the head of
the still is a pipe _T_ through which the vapors pass to a condensing
coil _f_ formed on the wall of the heater _C_. At its bottom the coil _f_
extends out of the heater, through the water tub _W_ and out to receiver
as at _F_. In the heat of this heater is a valve _V_ whereby any vapors
which may arise from the heated mash are conducted by pipe _U_ to _T_.
The heater _C_ is filled through funnel _Y_ and the mash is admitted to
the still through pipe _b_ having cock _a_. The pipe _P_ extends to the
upper part of the water tub _W_ and then downward to the bottom, where it
again enters the still.
An opening in the partition _d_ is controlled by a valve _G_ which allows
liquid in the upper compartment of the still to flow into the lower.
Spent mash may be drawn off through _c_ and the height of the water in
tub _W_ be regulated by pipe _Z_.
[Illustration: FIG. 13.--Compound Still.]
The operation of this still is similar to Dorn's still. Mash is put into
_C_ and a quantity of it is let into the upper compartment of the still
and into the lower compartment by valve _G_. This valve is closed and the
fire started. The vapors pass upward through _t_. If they are quite
highly vaporized they pass onward up _P_, are condensed in their passage
through the cool water tub and return as liquid to the upper compartment
where they are further heated.
The liquid in the upper compartment is thus constantly enriched and the
vapor therefrom passes out through pipe _T_ into condensing coils _f_
where it is condensed into spirit and passes off by _F_.
The funnel tube _Y_ acts also as a means of warning the attendant as to
the condition of the mash. If it is too high in level and the pressure of
vapor in the heater _C_ too great, liquid will be forced out of _Y_; if
on the contrary, the mash sinks below the level of the pipe then vapor
will escape and the heater needs refilling.
[Illustration: FIG. 14.--Compound Direct Fire Still.]
Fig. 14 shows a simple form of compound direct fire still as manufactured
by the Geo. L. Squier Mfg. Co., of Buffalo, N. Y.
Cellier-Blumenthal carrying this principle further devised an apparatus
which has become the basis of all subsequent improvements; indeed, every
successive invention has differed from this arrangement merely in detail,
the general principles being in every case the same. The chief defect in
the simple stills was that they were intermittent that is required the
operations to be suspended when they were recharged, while that of
Cellier-Blumenthal is continuous; that is to say, the liquid for
distillation is introduced at one end of the arrangement, and the
alcoholic products are received continuously, and of a constant degree of
concentration, at the other. The saving of time and fuel resulting from
the use of his still is enormous. In the case of the simple stills, the
fuel consumed amounted to a weight nearly three times that of the spirit
yielded by it; whereas, the Cellier-Blumenthal apparatus reduces the
amount to one-quarter of the weight of alcohol produced. Fig. 15 shows
the whole arrangement, and Figs. 16 to 17 represent different parts of it
in detail.
[Illustration: FIG. 15.--Cellier-Blumenthal Still.]
In Fig. 15 _A_ is a boiler, placed over a brick furnace; _B_ is the
still, placed beside it, on a slightly higher level and heated by the
furnace flue which passes underneath it. A pipe _e_ conducts the steam
from the boiler to the bottom of the still. By another pipe _d_, which is
furnished with a stop cock and which reaches to the bottom of the still
_A_, the alcoholic liquors in the still may be run from it into the
boiler; by turning the valve the spent liquor may be run out at _a_. The
glass tubes _b_ and _f_ show the height of liquid in the two vessels. _K_
is the valve for filling the boiler and _c_ the safety valve.
[Illustration: FIG. 16.--Details of Rectifier Column.]
The still is surmounted by a column _C_, shown in section in Fig. 16.
This column contains an enriching arrangement whereby the liquid flowing
down into the still _B_ is brought into intimate contact with the steam
rising from the still. The liquid meets with obstacles in falling and
falls downward in a shower, which thus presents multiplied obstacles to
the ascent of the vapor. The liquid is thus heated almost to the boiling
point before it falls into the still _B_. The construction for effecting
this is shown at _C_, Fig. 16 and consists of an enclosed series of nine
sets of circular copper saucer-shaped capsules, placed one above the
other, and secured to three metallic rods passing through the series so
that they can be all removed as one piece. These capsules are of
different diameters, the larger ones which are, nearly the diameter of
the column, are placed with the rounded side downwards, and are pierced
with small holes; the smaller ones are turned bottom upwards, a stream of
the liquid to be distilled flows down the pipe _h_ from _E_, into the top
capsule of _C_ and then percolating through the small holes, falls into
the smaller capsule beneath, and from the rim of this upon the one next
below, and so throughout the whole of the series until it reaches the
bottom and falls into the still _B_. The vapors rise up into the column
from the still and meeting the stream of liquid convert it partially into
vapor which passes out at the top of _C_ considerably enriched, into the
column _D_.
Fig. 16 shows a sectional view of the column _D_, the "rectifying column"
as it is called. It contains six vessels, placed one above the other, in
an inverted position, so as to form seals. These are so disposed that the
vapors must pass through a thin layer of liquor in each vessel. Some of
the vapor is thus condensed and the condensed liquid flows back into
column _C_, the uncondensed vapor considerably enriched passing up the
pipe _J_, into the coil _S_ in the condenser _E_, Fig. 17, which is
filled with the "wash" to be distilled.
[Illustration: FIG. 17.--Details of Condenser and Mash Heater.]
Entering by the pipe _t_, Fig. 15, the undistilled liquid or "wash" is
distributed over a perforated plate _y y_, and falls in drops into the
condenser _E_, where it is heated by contact with the coil _S_ containing
the heated vapors. The condenser is divided into two compartments by a
diaphragm _X_ which is pierced with holes at its lower extremity;
through these holes the wash flows into the second compartment, and
passes out at the top, where it runs through the pipe _h_, into the top
of the column _C_.
The vapors are made to traverse the coil _S_, which is kept at an average
temperature of 122∞ F., in the right hand compartment, and somewhat
higher in the other. They pass first through _J_ into the hottest part of
the coil, and there give up much of the water with which they are mixed,
and the process of concentration continues as they pass through the coil.
Each spiral is connected at the bottom with a vertical pipe by which the
condensed liquors are run off; these are conducted into the retrograding
pipe _p p_. Those which are condensed in the hottest part of the coil,
and are consequently the weakest, are led by the pipe _L_ into the third
vessel in the column _D_, Fig. 16, while the stronger or more vaporized
portions pass through _L¥_ into the fifth vessel. Stop-cocks at _m_, _n_,
_o_ regulate the flow of the liquid into these vessels, and consequently
also the strength of the spirit obtained.
Lastly, as the highly concentrated vapors leave the coil _S_ at _R_, they
are condensed in the vessel _F_, which contains another coil. This is
kept cool by a stream of liquid flowing from the reservoir _H_ into the
smaller cistern _G_ from which a continuous and regular flow is kept up
through the tap _v_ into a funnel _N_ and thence into condenser _F_. It
ultimately flows into condenser _E_ through pipe _t_, there being no
other outlet. The finished products run out by pipe _x_ into suitable
receivers.
It will be seen that the condenser _E_ has two functions. First it
condenses the alcoholic vapors before transmitting them to the final
condenser _F_, rejecting and sending back those vapors which are not
highly enough vaporized. Second it heats the wash intended for distilling
by appropriating the heat of the vapors to be condensed. Thus two birds
are killed with one stone. It will be noticed that the same result is
accomplished in the columns _C_ and _D_. This is the principle of all
modern stills.
Another form of still which is very analogous to that last described is
Coffey's apparatus, shown in Fig. 18, and is the immediate prototype of
the stills used to-day in all but the simplest plants.
[Illustration: FIG. 18.--Coffey's Rectifying Still.]
It consists of two columns, _C_ the analyser, and _H_ the rectifier,
placed side by side and above a chamber containing a steam pipe _b_ from
a boiler _A_. This chamber is divided into two compartments by a
horizontal partition _a_ pierced with small holes and furnished with four
safety valves _e e e e_. The column _C_ is divided into twelve small
compartments, by means of horizontal partitions of copper, also pierced
with holes and each provided with two little valves _f_. The spirituous
vapors passing up this column are led by a pipe _i_ to the bottom of the
second column or _rectifier_. This column is also divided into
compartments in precisely the same way, except that there are fifteen
of them, the ten lowest being separated by the partitions, which are
pierced with holes. The remaining five partitions are not perforated, but
have a wide opening as at _w_, for the passage of the vapors, and form a
condenser for the finished spirit. Between each of these partitions
passes one bend of a long zig-zag pipe _m_, beginning at the top of the
column, winding downwards to the bottom, and finally passing upwards
again to the top of the other column, so as to discharge its contents
into the highest compartment. The apparatus works in the following way:
The pump _Q_ is set in motion, and the zig-zag pipe _m_ then fills with
the wash or fermented liquor until it runs over at _n_ into the highest
compartment of column _C_. The pump is then stopped, and steam is
introduced through _b_, passing up through the two bottom chambers and
the short pipe _F_ into the analyzing column, finally reaching the bottom
of the other column by means of the pipe _i_. Here it surrounds the coil
pipe _m_ containing the wash, so that the latter becomes rapidly heated.
When several bends of the pipe have become heated, the pump is again set
to work, and the hot wash is driven rapidly through the coil and into the
analyzer at _n_. Here it takes the course indicated by the arrows,
running down from chamber to chamber through the tubes _h_ until it
reaches the bottom; none of the liquor finds its way through the
perforations in the various partitions, owing to the pressure of the
ascending steam.
As the liquid cannot pass through the holes in the partitions it can only
pass downward through the drop-pipe tubes _h_. By this means the mash is
spread in a thin stratum over each partition to the depth of the seal _g_
and is fully exposed to the steam forcing its way up through the holes,
the alcohol it contains being thus volatilized at every step.
In its course downwards the wash is met by the steam passing up through
the perforations, and the whole of the spirit which it contains is thus
converted into vapor. As soon as the chamber _B_ is nearly full of the
spent wash, its contents are run off into the lower compartment by
opening a valve in the pipe _V_. By means of the cock _E_, they are
finally discharged from the apparatus. This process is continued until
all the wash has been pumped through.
The course taken by the steam will be readily understood by a glance at
the figure. When it has passed through each of the chambers of the
analyzer, the mixed vapors of water and spirit pass through the pipe _i_
into the rectifying column. Ascending again, they heat the coiled pipe
_m_, and are partially deprived of aqueous vapors by condensation. Being
thus gradually concentrated, by the time they reach the opening at _w_
they consist of nearly pure spirit, and are then condensed by the cool
liquid in the pipe, fall upon the partition and are carried away by the
pipe _y_ to a refrigerator _W_. Any uncondensed gases pass out by the
pipe _R_ to the same refrigerator, where they are deprived of any alcohol
they may contain. The weak liquor condensed in the different compartments
of the rectifier descends in the same manner as the wash descends in the
other column; as it always contains a little spirit, it is conveyed by
means of the pipe _S_ to the vessel _L_ in order to be pumped once more
through the apparatus.
=The condensed spirit= gathered over the plates _v_ passes out through
the pipe _y_ to the condensing worm _T_. If any vapors escape the
condensing plates they pass into _R_ and are condensed in the worm _T_
also. From worm _T_ the spirit flows into a suitable receiver _Z_.
Before the process of distillation commences, it is usual, especially
when the common Scotch stills are employed, to add about one lb. of soap
to the contents of the still for every 100 gallons of wash. This is done
in order to prevent the liquid from boiling over, which object is
effected in the following way: The fermented wash always contains small
quantities of acetic acid; this acts upon the soap, liberating an oily
compound which floats upon the surface. The bubbles of gas as they rise
from the body of the liquid are broken by this layer of oil, and hence
the violence of the ebullition is considerably checked. Butter is
sometimes employed for the same purpose.
Figs. 19 and 20 show a diagrammatic section and a plan of a still used
for thick mashes which are liable to burn. This comprises a circular
chamber _B_ supported over suitable heating means, having on its bottom a
series of concentric partitions _b_ which divide the bottom of the
chamber into shallow channels for the mash. Running diametrically through
the chamber is a partition.
[Illustration: FIG. 19.--Rotary Current Still.]
The mash passes from a tank as _A_ by a passage _a_ to an opening on one
side of the central portion and into the outside channel _b_. The current
of liquid passes along the outer channel until it is deflected by the
central partition into the next interior channel _b_ and so on until it
arrives at the center when it passes through the central partition into
the other half of the chamber. Here it passes around back and forth and
gradually outward to the outermost channel from which it passes off
through an adjustable gate in outlet _c_. By adjusting this gate, and a
gate or cock in inlet passage _a_, the passage and consequent depth of
the liquid in the channels may be regulated. The vapor rising from the
mash is carried over to a condenser through pipe _D_. In order to keep
the mash from burning a chain _g_ is rotarily reciprocated along the
channels by means of the bar _G_, the gear _E_ and the crank shaft _e_.
Various modifications of this construction have been devised. The
advantage of the still lies in submitting the mash in a thin current to
the action of the heat, and the consequent rapid vaporization.
[Illustration: FIG. 20.--Rotary Current Still.]
Every distillation consists of two operations: The conversion of liquid
into vapor, and the reconversion of the vapor into liquid. Hence perfect
equilibrium should be established between the vaporizing heat and the
condensing cold. The quantity of vapor must not be greater or less than
can be condensed. If fire is too violent the vapors will pass out of the
worm uncondensed. If the fire is too low the pressure of the vapor is
not great enough to prevent the entrance of air, which obstructs
distillation. As a means of indicating the proper regulation of the fire,
the simple little device shown in Fig. 21 may be used.
This consists of a tube of copper or glass having a ball _B_ eight inches
in diameter. The upper end _E_ of the tube is attached to the condensing
worm. The lower end of the tube is bent in U-shape; the length of the two
bends from _b_ to outlet is four feet. The ball has a capacity slightly
greater than the two legs of the bend.
[Illustration: FIG. 21.--Indicator for Regulating the Distilling Fire.]
Normally the liquid in the two legs will stand at a level. If, however,
the fire is too brisk the vapor will enter the tube and drive out the
liquor at _d_, and thus the level in the leg _C_ will be less than in the
leg _D_. If, however, the fire is low, the pressure of vapor in the worm
will decrease and the pressure of the outside air will force down the
liquid in leg _D_ and up leg _C_ into the ball.
A more perfected device but operating on the same principle is shown in
Fig. 26.
It is obviously impossible to present in the small compass of this book a
description of all the varieties of stills used, but these which have
been described illustrate the principles on which all stills are
constructed and were chosen for their simplicity of construction and
clearness of their operation. The principle of their operation is exactly
the same as the more modern forms now to be described.
CHAPTER IV.
MODERN DISTILLING APPARATUS.
In the previous chapter we have given a description of small, simple
stills, such as were used until late years, and which are yet used in
many localities where distilling is carried on on a small scale. We will
now describe the principle features of more complicated and elaborate
apparatus.
All modern distilling apparatus for the production of a high grade of
alcohol is based upon the principle set forth in the description of the
Coffey still; that is, upon using a distilling column and a concentrating
column, wherein the "wash" or mash fermented as described, passes over a
series of plates or other obstructions in contact with an ascending
column of heated vapor. This heated vapor extracts the alcohol from the
wash, or from the low wines of the concentrator, and is continually
strengthened during its journey until it passes off to a condenser as a
vapor very rich in alcohol. The converse of this is true with the wash,
which in its downward course is gradually deprived of its alcohol until
it finally passes off at the bottom of the column.
[Illustration: FIG. 22.--Diagramatic View of Column Still and Accessory
Apparatus. (_To face page 64_)]
Fig. 22 is illustrative of the general form and arrangement of such a
column and its adjuncts; the details, however, will vary with each make
of still. In this the "column" consists of a casing really continuous but
divided into two portions--the distilling portion _A_ and the rectifying
portion _B_. The operation is alike, however, in principle in both
portions.
[Illustration: Cross-Section of Fig. 23.]
[Illustration: FIG. 23.--Distilling Plate.]
The wash by means of a suitable pump is forced into an overhead tank or
concentrator _G_ where it is warmed by the hot vapors as will be later
described. It passes around the interior of the concentrator in a coil
_c_ and then passes off by a pipe _a_ to the uppermost plate of the
distilling portion _A_ of the column.
The plates, as before explained on page 55, are each formed with a
dropping tube _O_ (see Fig. 23), which extends above the plate to an
extent slightly less than the desired thickness of the layer of liquid on
each plate, and with perforations each having an upwardly projecting rim,
and each covered with a cap _A_. This rim and cap form a trap. The
ascending vapors pass up through the perforations, down between the rim
and the edge of the cap and thus out through the layer of wash contained
on the cap. The wash remains constantly level with the top of the tube
_O_, the excess running off through the tube _O_ to the compartment or
plate beneath.
To return to Fig. 22, the wash by the pipe _a_ enters the distilling
portion of the column at the uppermost plate thereof and, as described
above, drops down from plate to plate. A steam pipe _S_ enters the bottom
compartment of the distilling portion of the column and the steam as it
rises through the little traps, bubbles out through the layer of wash and
in each compartment enriches itself with alcohol. Thus the rising column
of vapor is constantly becoming richer and the downward current of wash
constantly weaker until at last it passes away as spent wash at the very
bottom of the column by the pipe _D_.
The hot vapors, as before described, pass upward and enter the rectifying
portion of the column _B_. This consists of a series of compartments
having perforated bottoms and dropping tubes. The vapor passes upward
through these perforations of the plates,--the condensed portion of it
dropping back again on to the lower plates or on to the distilling plates
to be again vaporized and concentrated and the more highly vaporized
portion passing out at the top of the column through the pipe _E_ to the
concentrator _G_.
The concentrator consists of a tank containing water within which is
supported a vessel _F_ having double walls. The interior of this vessel
is likewise filled with water. Between the double walls and surrounding
the coiled pipe _c_ passes the vapors from pipe _E_.
At the bottom of the vessel _F_ is a compartment _f_ connected by a pipe
_F¥_ with the upper compartment of the rectifying column. The less highly
heated vapors will be condensed by the passage through the double walls
of the vessel and the condensation will collect in the compartment _f_,
and from there pass off by pipe _F¥_ back to the rectifying column, to be
again vaporized and strengthened by the descent from plate to plate of
_B_.
The rich and highly vaporized vapors which have passed the test of this
preliminary concentration, pass out of the compartment _f_ by a pipe _M_.
Here again the water surrounding the pipe tends to condense all but the
most highly charged vapor and send it back to compartment _f_ but the
vapor which succeeds in passing over through pipe _G_ is carried downward
to a condenser _H_ where it is finally condensed and drawn off as at _g_.
It is necessary that the rate of mash feed be regulated so that neither
too much mash shall be pumped into the mash heater _G_, or too little,
and the pipe leading from the pump to the heater is therefore provided
with a tap and an indicating dial.
In these modern stills the following are particularly important points to
be especially brought to the consideration of the distiller.
It cannot be too strongly impressed that effectiveness of the distilling
column depends on the plates dividing it,--that is, upon the
horizontality of the plates and the form of the traps or perforations. If
the plates are not horizontal the wash is not maintained at a uniform
level across the entire extent of the plate and hence some of the
ascending vapor will pass out without contacting with the wash through
uncovered traps, while others of the traps will be so deeply submerged in
wash that the vapor cannot bubble through.
Again the caps should be so made as to divide the vapor into fine streams
and bring it into contact with each part of the wash. Plates simply
perforated and uncapped give excellent results for they molecularize the
vapor ascending through the liquid contained on the plates, but they
require a constant pressure of vapor, and any variations of pressure
tends to discharge them. In addition these perforations gradually enlarge
by the action of acids in the wash or clog up, and the apparatus soon
works badly.
Good forms of capped traps are those shown in Figs. 24, 25 devised by
Barbet. These are provided with an interior upwardly projecting rim.
Extending over the rim and down around it is a copper cap having its
margin slitted.
The wash carried on the plate circulates about the caps and the alcoholic
vapors bubble out through the slits and up through the wash, the vapor
thus being finely divided and coming into intimate contact with each
portion of the wash and thus more thoroughly depriving it of its alcohol.
[Illustration: FIG. 24.--Barbet Trap.]
[Illustration: FIG. 25.--Barbet Trap.]
Besides this there is another advantage resident in these caps, namely,
that distillation may be stopped for several hours and then re-started
without trouble for the reason that the wash has been retained on the
plates, whereas were the plates simply perforated the wash would ooze
through and the plates have to be recharged. This form of plate may be
easily repaired and does not necessitate the removal or replacement of
the plate itself. The caps alone need be removed.
For thick washes, which tends to obstruct the slits of the cap, Barbet
has devised the cap shown at the right in Fig. 25. This cap extends down
to the plate itself, and has very narrow slits in its periphery. With
such a cap as shown in Fig. 24, the bran, sediments, etc., would tend to
settle upon the top of the cap, enter beneath it and through the slits.
The cone-shape of the top of this cap prevents the deposit of dregs
thereon and the very narrow slits oppose the entrance of bran or
sediment.
While, for the sake of clearness, an old form of concentrator, _G_, has
been shown, the concentrator, preheater for the wash, and condensers,
to-day, are usually composed of bundles of tubes through which the vapors
pass surrounded by water or the cool wash. These should be of bronze or
copper and made without solder. The tubes should be capable of being
taken out for cleaning or repairing.
In many distilling apparatuses the distilling column and the rectifying
column are in two parts, one beside the other. This overcomes the
objection of having a very high column and also prevents the low wines,
_i.e._, the weak alcoholic liquor after its first concentration, from
passing into the wash as it would do with the continuous column.
[Illustration: FIG. 26.--Steam Regulator.]
In order that the amount of steam entering the column may be regulated,
the column is usually provided with a steam regulator (Fig. 26); whose
principle of operation may be easily under stood by referring to Fig. 22.
It comprises an upper and a lower chamber _Z Z¥_ connected by a central
tube _K_ which projects down nearly to the bottom of the lower chamber. A
pipe _W_ communicates with the steam chamber _R_ of the column and enters
the chamber _Z_ above the level of the water contained therein. In the
upper chamber _Z¥_, is a float _X_, connected to the differential lever
_T_ of a steam valve _T¥_ which controls the inlet of steam passing
through pipe _S_ to the steam chest _R_. The principle of operation is
very simple. When the pressure in the steam chest _R_ becomes too great,
steam in the pipe _W_ and chamber _Z_ forces the water therein up in tube
_K_, thus lifting the float _X_ and closing the steam entrance valve
_T¥_. When the pressure of steam is low, the level of the liquid in _Z_
rises and liquid in _Z¥_ runs into _Z_, the float _X_ falls opening valve
_T¥_ and allowing a greater flow of steam.
As it is often desirable to change the pressure of steam in the column at
various points in the operation, the best regulators are usually provided
with means to that end.
[Illustration: FIG. 27.--Gauge Glass for Regulatur.]
In order to measure the output of the still, there is attached thereto a
gauge glass (_J_ in Fig. 22), a diagram of which is shown in Fig. 27.
This consists of a jar _A_ connected at its lower end at _b_ by an
annular passage _B_ to a chamber _E_ from which proceed the taps _F_.
Centrally through the passage _B_ passes a tube _c_ connected at its
lower end to the pipe _C_ leading from the condenser. The tube _C c_
projects upward into the jar _A_ and is open at its upper end.
Now the opening _b_ is of a certain size and it is obvious that it will
carry off a certain amount of liquid when running full or the amount
allowed to flow out by the exit tap _F_. If now, more than that quantity
of alcohol is produced, the alcohol will rise in the jar _A_ until the
rate of inflow and outflow is equal. If, however, the still is producing
less than that quantity then the level of liquid in _A_ will gradually
drop. Hence, by observing the level of the liquid in _A_ and its
constancy or variation in level, it is possible to tell precisely how
much alcohol is running per hour and if the rate is steady. The jar _A_
is provided with a cap _G_ whereby an alcoholometer may be inserted
into tube _c_ for the purpose of testing the strength of the liquor. The
taps _F_ are for the purpose of collecting the first runnings, the pure
alcohol and the last runnings or "feints."
These principles are also embodied in the apparatus designed by the
Vulcan Copper Works Co., of Cincinnati, and illustrated in Fig. 28. The
apparatus comprises the still, a wash heater and a condenser. The still
is composed of a series of chambers from 12 to 24, the internal
construction of which is shown in Fig. 29. Each chamber consists of a
peculiarly perforated plate _A_, a drop pipe _B_, a seal _C_, into which
the drop pipe from the plate above projects, and a central standard _D_.
Returning now to Fig. 28, at the bottom of the column is a manifold _E_,
with pipes _F_ and _G_ whereby either exhaust or live steam may be
admitted. _H_ designates the discharge or slop valve, controlled by a
float _I_ whereby a constant level of slop or spent wash is kept in the
bottom chamber.
[Illustration: FIG. 28.--Continuous Distilling Apparatus, with External
Tubular Condenser. (_To face page 72_)]
To the right of the column is seen the slop tester _J_ and hydrometer
_L_, whereby the spent wash may be tested to see if the spirit is being
properly extracted. The steam pressure is indicated by means of a float
_N_ contained within a vessel _M_, a tally weight moving against a scale
_K_, showing the pressure of steam entering through pipe _O_ and acting
against water contained in vessel _M_. Each chamber is provided with a
manhole plate _P_, and a try-cock _Q_, whereby the operation of each
chamber may be tested. _R_ is a gage glass to show the level of the slop
in the bottom chamber.
At the top of the column are three rectifying chambers fitted with
boiling pipes and traps _T_, which distribute the ascending vapor and
boil out the low wines returned from the wash-heater or fore-warmer.
[Illustration: FIG. 29.--Detail of Chamber, Continuous Still.]
The heater consists of a shell enclosing a series of tubes extending into
an upper and lower chamber. The wash or "beer," is pumped into the lower
chamber of the heater, and passes upward through the tubes to the upper
chamber from which is it carried by a pipe to the plate _A_ next below
the rectifying plates.
[Illustration: FIG. 30.--Detail of Perforated Plate _A_.]
The vapor from the column passes into the middle compartment of the
heater and surrounds the beer tubes. The vapors give their heat to the
beer and are thus cooled, the low wines being condensed and flowing back
onto the uppermost rectifying plate, while the highly vaporized portions
pass out to the condenser. This is of the same general construction as
the heater, the vapor being cooled and condensed to liquid by the tubes
through which a constant current of cool water is passed. This enters at
_U_ and passes out at _V_. These tubular condensers are particularly good
as they may be easily cleaned. From the condenser the spirit passes to a
discharge box _W_. A portion of the flow passes into a test tube _X_,
provided with a hydrometer. A trap _Y_ and an air pipe _Z_ provide means
for the escape of gas.
As before stated, the form of perforations in the plates of a column
through which the vapor pass upward through the beer or wash is
particularly important. The steam must be thoroughly diffused through the
beer, or else particles of mash are carried up, accumulate around the
perforations, baking there and clogging them up. The clogging and
eventual stoppage of the perforations prevent the agitation of the mash
carried on the plate, and a layer of mash accumulates and bakes on the
head, or plate, above. Thus the operating capacity of the still is
reduced and a larger quantity and greater pressure of steam is necessary
with consequent waste of fuel.
[Illustration: FIG. 31.--Detail of Perforated Plate _A_.]
It is necessary then that the form of perforation or trap through which
the vapor ascends should be such that agitation of the beer shall be
enforced in its movement across the plate, and that the steam shall be
thoroughly diffused through the beer. In the Vulcan still above referred
to, these results are accomplished by forming each perforation with a
tongue, as shown in the fragmentary view of a plate, Figs. 30 and 31, the
tongues of all the holes being directed towards the periphery of the
plate. It is claimed that by this construction the steam is diverted
forward and injected into the beer, throwing the beer into vigorous
motion, completely diffusing the steam and accelerating the motion of the
beer from the seal _C_ to the drop pipe _B_.
[Illustration: FIG. 32.--Continuous Distilling Apparatus with Goose
Separator. (_To face page 76_)]
Fig. 32 illustrates another form of distilling apparatus manufactured by
the same company, which is practically the same as the apparatus
previously described except that it is provided with a "goose-necked"
separator, interposed between the wash-heater and the enclosure. This
consists of a series of convoluted tubes contained in a tank of cold
water. The vapor from the heater passes into these convolutions. The
heavier vapors are condensed therein and returned to the heater from
which they descend into the column while the more volatilized vapors pass
over into the final condenser. The _U_-bends at the bottoms of each
convolution act like so many low wine chambers in the still shown in Fig.
9 the highly heated vapor continually bubbling through the condensed
vapor in the _U_ bend and there becoming greatly enriched and
concentrated.
This apparatus, it is claimed, is applicable to the distillation of
grain, molasses or cane juice and will yield 170 or 180 per cent., or the
equivalent to 85-90 G. L. or 34-36 Cartier.
[Illustration: FIG. 33.--Section of Gillaume's Inclined Column Still.]
A distinctly modern type of still, though akin to the still shown in
Figs. 19 and 20, is the inclined column of Gillaume, shown in section in
Fig. 33 and in full view in Fig. 34. Gillaume in devising this form of
apparatus had particularly in mind the distillation of thick washes, and
the necessity of compelling a circulation of the wash.
[Illustration: FIG. 34.--Gillaume's Inclined Column Still.]
The bottom of the inclined column _A_ is divided by lateral extending,
upwardly projecting plates or partitions _a_ forming a continuous
channel through which the wash passes from side to side and from top to
bottom and then out through a regulator. The upper plate of the column
has downwardly projecting partitions _b_ which with the partitions _a_
form a series of traps. The steam enters at the bottom of the column into
a reservoir, and in order to pass upward is forced beneath each partition
_b_ and through the washer contained in the channels of the bottom. When
it reaches the upper end of the column it has passed through a continuous
series of wash-filled compartments containing a constantly moving current
of wash.
The vapors from the top of the column pass off to the wash heater or to a
concentrator.
In Fig. 34 is shown a form of Gillaume still designed to distill all
sorts of liquids whether thin or thick. The wash is supplied from an
overhead tank to a regulating tank _K_ from which a pipe _k_ leads to a
regulating tap _m_. The wash re-ascends into the wash heater _B_ and when
heated descends by pipe _F_ into the uppermost compartments of the column
_A_. The vapor passes to the condenser _B_, by a pipe _H_, and the spent
wash is discharged by a siphon _C_. In addition to the parts above
referred to, _a_ designates entrance of wash into heater, _b_ exhaust
test tube, _d_ steam entrance tap _G_ alcohol test glass, _G¥_ exhaust
test glass, _o_ valve for regulating strength of spirit, _O_ steam
regulator, _p_ water entrance tap, _r_ exit tap, and _D_ the spent wash
extractor.
The Gillaume apparatus is particularly valuable for the production of
industrial or agricultural alcohol. It is claimed that it is easily
understood and operated even by unskilled labor, while it produces a
large proportion of alcohol of a high strength.
A view of a complete apparatus on a large scale is shown in the Fig. 40
in the chapter on rectification.
CHAPTER V.
RECTIFICATION.
The product of the distillation of alcoholic liquors, which is termed
_low wine_, does not usually contain alcohol in sufficient quantity to
admit of its being employed for direct consumption. Besides this it
always contains substances which have the property of distilling over
with the spirit, although their boiling points, when in the pure state,
are much higher than that of alcohol. These are all classed under the
generic title of _fusel-oil_; owing to their very disagreeable taste and
smell, their presence in spirit is extremely objectionable. In order to
remove them, the rough products of distillation are submitted to a
further process of concentration and purification. Besides fusel-oil,
they contain other substances, such as aldehyde, various ethers, etc.,
the boiling points of which are lower than that of alcohol; these must
also be removed, as they impart to the spirit a fiery taste. The whole
process is termed _rectification_, and is carried on in a distillatory
apparatus.
As before stated, the wash as discharged into the still consists of
alcohol mixed with water and a variety of impurities from which the
alcohol must be separated. In order that the process may be better
understood we will assume that a mixture of pure alcohol and water is to
be operated on in place of the wash as above referred to. Distillation in
this case is intended to deprive the water of its alcohol, the operation
theoretically leaving water in one chamber and alcohol in another. This
is accomplished by reason of the differences in the boiling points of
water and alcohol. The alcohol vaporizes at a lower degree (173∞ F.) than
water (212∞ F.) Thus the liquid at the end of the operation has been
divided into two parts or _fractions_.
This, however, is not a clean division for the reason that while in the
beginning the vapors contain a large quantity of the more volatile
alcohol, at the end they will contain a large portion of the less
volatile water. The whole of the alcohol will be separated in this
manner, but it will still be mixed with some water and in order to again
divide the alcohol from the water the first distillate would have to be
redistilled until at last the water is reduced to a minimum or entirely
eliminated, if possible.
But as it requires less heat to vaporize alcohol than water, so it also
requires more cold to condense alcoholic-vapor than water-vapor. If then
we pass the mixed vapors into a condensing chamber cooled to a certain
temperature low enough to condense water-vapor but not the alcohol-vapor,
then the water-vapor will fall down as water while the alcohol-vapor
being uncondensed passes on to another chamber where its temperature
falls to a point where it in turn condenses into liquid.
In intermittent distillation, as by the simple still, the vapors of mixed
alcohol and water at first contain a great deal of alcohol and a little
water, then more water and less alcohol, and then a great deal of water
and hardly any alcohol. It may be asked: "Why not take only the runnings
rich in alcohol and leave the others?" The answer to this is that if this
be done then _all_ the alcohol is not extracted from the wash and there
is just that much loss. The solution of the problem is to get all the
alcohol out mixed with the water that is inevitably with it and then
redistill this result thus getting out (sifting away) some of the water,
and again distill this result, and so on until only pure alcohol is left.
This, however, is a very troublesome business and has been abandoned as a
means of removing impurities such as water, the ethers, and fusel oil
except by makers of whiskey, brandy and other beverage spirits, in favor
of continuous distillation and continuous rectification.
It will be seen from what has gone before that there are two means of
separating alcohol and water; one by an initial difference in heating and
by a further difference in cooling or condensing.
It is on this foundation that the whole art of fractional distillation or
rectification rests. While we have for illustration been considering a
mixture of pure alcohol and water, the wash or liquid formed by the
fermentation of grain, etc., contains a variety of ingredients of
different boiling points, some more volatile than alcohol, some less. The
fermented wash consists first of non-volatile or only slightly volatile
matters, such as salts, proteins, glycerin, lactic acid, yeast, etc., and
second, volatile bodies such as alcohol, water, various ethers, etc.,
fusel oils and acetic acid.
When wash is distilled in the ordinary simple or pot still, the first
part to come over consists of the very volatile matters,--more volatile
than alcohol even,--that is, the ethers mixed with some alcohol. This is
known as the fore-shot or first runnings, and is collected separately.
When the spirit coming over possesses no objectionable odor, the second
stage has begun. This running would be of the alcohol proper, getting
weaker and weaker, however, as the running continues and this would be
caught separately as long as it is of sufficient strength. At last would
come the weak spirit containing much fusel oil. It is to be understood,
however, that there is no defined line between these divisions. They
graduate one into the other. The first and last runnings in the old
practice were mixed together and distilled with the next charge. When a
strong spirit was required, rectification would be repeated several
times. It is customary, however, with the improved modern apparatus, to
produce at the outset spirit containing but little fusel oil and at least
80 per cent of alcohol. This is then purified and concentrated in the
above manner and afterwards reduced with water to the required strength.
Another cause of the offensive flavor of the products of distillation is
the presence of various acids, which exist in all fermented liquors; they
are chiefly tartaric, malic, acetic, and lactic acids. The excessive
action of heat upon liquors which have been distilled by an open fire has
also a particularly objectionable influence upon the flavor of the
products.
The first operation in the process of rectification is to neutralize the
above-mentioned acids; this is effected by means of milk of lime, which
is added to the liquor in quantity depending upon its acidity; the point
at which the neutralization is complete is determined by the use of
litmus paper. In the subsequent process of distillation, the
determination of the exact moments at which to begin and to cease
collecting the pure spirit is very difficult to indicate. It must be
regulated by the nature of the spirits; some may be pure 20 or 30 minutes
after they have attained the desired strength; and some only run pure an
hour, or even more, after this point. The product should be tasted
frequently, after being diluted with water, or a few drops may be poured
into the palm of the hand, and after striking the hands together, it will
be known by the odor whether the spirit be of good quality or not; these
two means may be applied simultaneously.
[Illustration: FIG. 35.--Rectifying Still.]
The process of rectification may be carried on in the apparatus shown in
Figs. 35 and 36. _A_ is a still which contains the spirit to be
rectified; it should be four-fifths full. The condenser _E_ and the
cooler _G_ are filled with water. After closing the cocks _L_ and _I_,
the contents of the still are heated by steam, which is introduced at
first slowly. The vapors of spirit given off pass, by tubes _b_, above
each plate _a_, of the series in column _B_, and escape through _C_ and
_D_ into the condenser _E_, where they are condensed on reaching the
lentils _d d¥_, and return in a liquid state through pipe _f_ and
connections _g g¥_ to the upper plates of the column _B_. In these return
pipes the liquid is volatilized, and constantly recharged with alcohol to
be again condensed, until the water in the condenser is hot enough to
permit the lighter alcoholic vapors to pass into the coil _c c c_,
without being reduced to the liquid state. When this is the case, the
vapors pass through _F_ into the cooler _G_, where they undergo complete
condensation. Great care must be taken that the heat is not so great as
to permit any of the vapors to pass over uncondensed or to flow away in a
hot state; and also to keep up a constant supply of water in the cooler
without producing too low a temperature; the alcoholic products should
run out just cold. The highly volatile constituents of the spirit come
over first, that which follows becoming gradually purer until it consists
of well-flavored alcohol; after this comes a product containing the
essential oils. The more impure products are kept apart from the rest
and re-distilled with the next charge. Some hours generally elapse before
alcohol begins to flow from the cooler. The purest alcohol is obtained
while its strength is kept between 92∞ and 96∞ Baume, and the operation
is complete when the liquid flowing through the vessel marks not more
than 3∞ or 4∞ Baume; it is better, however, to stop the still when the
backing or "faints" indicate 10∞, because the product after this point
contains much fusel-oil, and is not worth collecting.
[Illustration: FIG. 36.--Section of Rectifying Still.]
In order to cleanse the apparatus--which should be performed after each
working--the still _A_ is emptied of water by opening the cock _Q_. The
contents of the condenser are then emptied in like manner by opening the
cock _J_, through which they flow upon the plates in the column _B_, and
wash out essential oils which remain in them. These two cocks are then
closed, and the door _U_ in the still head is removed. The water in the
cooler _G_ is then run by means of pipe into the still _A_, so as
partially to cover the steam-coil in the latter. After again securing the
door _U_, a strong heat is applied, and the water in the still is well
boiled, the steam evolved thoroughly cleansing all the different parts of
the apparatus; this is continued for 15 or 20 minutes, when the heat is
withdrawn and the still left to cool gradually.
In the intermittent rectifying still above described the impure products
are distilled with the next charge. In the apparatus as perfected and
used in large distilleries or rectification plants, the division of the
several products composing the phlegm or raw spirit is made at one time
and continuously on the principle now to be described.
It was stated in the beginning of this chapter that the various
impurities in alcohol, the ethers, the water and the fusel oils, have
each their own vaporizing point and each their own condensing point. As
this is so, they may be separated from each other and from the alcohol on
the same principle as we have seen that water is separated from the
mixture of pure alcohol and water; that is, by fractionation, as it is
termed, or by "sifting out" one body from another.
[Illustration: FIG. 37.--Fractional Distilling Apparatus.]
Thus in fractional distillation, each condenser or retort in the
apparatus shown in Fig. 37, above acts as a sieve or trap, letting pass
the most volatile substances but retaining those of a less degree of
volatility. By passing the mixed vapor together through a good condensing
medium the temperature of which is lower than the boiling point of the
less volatile, but not so low as the boiling point of the more volatile
the vapors of the less volatile liquid will be condensed, while the more
volatile will retain their gaseous form. Thus by having a number of
condensing mediums each one slightly lower in temperature than the other,
the various vapors with their various points of volatilization will be
successively condensed, allowing the passage of the more volatile vapors
over to the condenser beyond.