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.

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.

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_.

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.

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.

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.

=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.

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_.

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.

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.

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.

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.

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.

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.

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.

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.

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.