82 ALCOHOL.— Distillation. Adam’s Still.

again sets the pump to work, and the wash, nownearly "boiling hot, and always in rapid motion, flowsfrom the pipe m at n', and passes down from cham-ber to chamber through the dropping pipes, in thedirection shown by the arrows in a few of the upperchambers. It may be here observed that no portionof the wash passes through the small holes perforatedin the diaphragms which separate the chambers.These holes are regulated, both in number and size,so as not to be more than sufficient to afford apassage for the vapours upwards, when under somepressure. The holes, therefore, afford no outlet forthe liquor, which can only find its way down in thezig-zag course indicated by the arrows. It is there-fore • obvious that the wash, as it passes down, isspread into as many strata as there are diaphragms,and is thus exposed to the most searching action ofthe steam constantly blowing up through it. As itfalls from chamber to chamber its alcohol is volatil-ized by the steam passing upwards; and by the timethe wash has reached the large chamber, B, no traceof the spirit remains. The wash, as it descendsfrom the analyzer, accumulates in the large cham-ber, b'. When this vessel is nearly filled, whichcan be perceived by inspection of the glass tube,the attendant opens the valve of the pipe, v,and discharges the contents of b' into the lowercompartment: then shutting the valve, the washfrom the analyzer again accumulates in b', and whenit is nearly full, the contents of the lower chamberare discharged from the apparatus altogether, throughthe cock, n', and the charge in b' let down by open-ing the valve, v, as before; thus the process goeson so long as there is any wash to supply the pump.

When all the wash is gone, water is let into thereservoir, L, and pumped through the pumps, m m,to obtain the last portions of alcohol.

It has been already said, that in the ordinarycourse of the operation the wash is stripped of allits alcohol by the time it has reached the bottom ofthe analyzer; but as a precautionary measure thechambers, p/ b", have been superadded, in each ofwhich the spent wash is exposed for about half anhour to the action of the steam blowing through it.There is a small apparatus—not shown in the en-graving—by which a portion of the steam in thechamber, b", is condensed, cooled, and made to flowconstantly through a sample jar, in which is ahydrometer, or what is better, two glass bulbs, oneof the spec. grav. l’OO, and the other, 0 - 998. Theattendant knows all is right when the lighter ofthese bulbs floats in the sample ; hence the cham-ber, B, may be emptied without any risk of loss.

The course of the wash being understood, that ofthe steam requires very little description.

The steam is first blown through the charges ofspent wash in the lower chamber of B, thence itpasses up through the layers of wash on the elevendiaphragms of the analyzer. In its course it abstractsalcohol from these layers of wash, depositing waterin its place. After traversing the whole of theanalyzer, the vapour, now containing much alcohol,passes by the pipe, i, into the bottom of the rectifier,

and as it ascends it envelopes the pipes m m, heat-ing the wash, and simultaneously parting with itsmore watery portion, which is condensed, and fallsin a state of ebullition on the several diaphragms ofthe rectifier. By the time the vapour reaches thepassage, w, in the bottom of the finished spiritcondenser, it is nearly pure alcohol; and as it iscondensed by the wash in the pipes, and falls on thediaphragm, it is conveyed away by the pipe, y , to arefrigerator. At the top of the spirit condenser is alarge pipe, R, which serves as a vent for the uncon-densable gas disengaged in the process, and thispipe also communicates with the refrigerator, sothat should alcoholic vapour at any time pass out ofthe apparatus, no loss is sustained beyond the wasteof fuel caused by condensing it by the water of therefrigerator, instead of the wash of the condenser.

The liquor formed on the several diaphragms ofthe rectifier descends to the bottom in the samemanner as the wash falls from chamber to chamberin the analyzer; but as it still contains alcohol, it isconveyed by the pipe, s, to the pump, Q, by whichit is raised up with the wash to be again distilled.

A thermometer at m' shows the attendant thetemperature of the wash as it issues from the pipe,in m, into the analyzer, being the only guide herequires for managing the operation: for when thetemperature is what it should be, nothing can gowrong in the work. Whenever the thermometerindicates too high a temperature, more wash is letinto the apparatus, and vice versa —the quantitybeing regulated by the tap and the pipe, n. Verylittle nicety is requisite on this point, the fluctua-tion of a few degrees above or below the properheat is of little consequence, and it is very seldomfound necessary to alter the supply of wash.

The water for supplying the boiler passes througha long coil of pipe immersed in boiling-hot spentwash, by which means it is raised to a high tempera-ture before it reaches the boiler.

The vapour passing through this apparatus iscondensed by the wash, and not by water ; and noheat is wasted as in the common process.

The continental savans at an early date improvedthe forms of stills. PoiSSONlER, in the year 1779,proposed a modification of the common still, whichwould probably have come into general use, had itnot been for the better and more ingenious inven-tion of M. Adam, before alluded to. Being anauditor of a course of chemical lectures at Mont-pellier , during which the merits of Woulfe’s appara-tus as a condenser was discussed, Adam conceivedthe idea of constructing a still in which the princi-ples of the apparatus of Glauber and Wouli-eshould be applied to the condensation of alcoholicvapour. In 1801 he took a ten years’ brevet, orpatent, for his invention, and since that time acomplete revolution has been effected in the art ofdistillation. About the same time Solimani obtaineda patent for another form of distillatory apparatus.This gentleman was a physician at Nimes , andformerly lecturer on chemistry and experimentalphilosophy, and disputed the priority of his in-