184
adapted, resting upon blocks or ledges, ff in theinterior of the vessel. The lid is rendered air-tight
by means of otherFi s- *■ bars of metal, e e,
• which are solderedfast on the outsideover the interior ones.From the middle of'the cover an ironpipe, c, rises, to theorifice of which an-other pipe, d, bent atright angles, is sol-dered, for the pur-pose of conductingthe ammoniacal va-pour to the con-densers, which aresimilar to those al-ready described. A
-J- ( -1—,—1--— i -much larger quantity
j-*—J- 1 —j—*—|-. of water must be
i i ! I used in this apparatusthan in the preceding one; and as distillation ad-vances, it is necessary to keep up the supply through-out the process, that the solder may not melt, acircumstance which would happen were this precau-tion overlooked.
As the demand for ammonia and its salts becamegreater, its manufacture received an additional im-petus, and many patents have been granted for itspreparation; most of them, however, relate to theproduction of the salts of ammonia.
Mr. Young, in 1841, took out a patent for prepar-ing ammonia from guano; the method which herecommends is the annexed:—The retorts are filledvertically with two parts by weight of guano, and onepart by weight of hydrate of lime, or other causticalkali, and the whole is intimately mixed by the aidof an agitator placed in the retort, Having wellmingled the materials, the retorts are moderatelyheated, and this heat is gradually increased to red-ness. The combined action of the heat and alkalinecompounds disengages all the ammonia, whether itbe in the form of salts or other complex bodies, suchas urea or uric acid, and the gas thus liberated isreceived into a condenser filled with water. Othergases and fluids are evolved together with the am-moniacal vapour, the uncondensable portions ofwhich pass through the condenser unaffected.
An ammoniacal solution is obtained by the destruc-tive distillation of bituminous schist, by Count deIIompesch, who rendered it available for the manu-facture of ammoniacal salts.
The method adopted by Watson for manufac-turing ammoniacal liquor from gas liquor is as fol-lows :—The gas liquor is run into a capacious retort,and a suitable quantity of slaked lime added—theamount being determined by the quality of the crudeliquor; heat is then applied, and ammonia, tolerablypure, distils over, which, on being received in a ves-sel of cold water, forms an ammoniacal liquor.When considerable quantities of stpain are observed
A A A A A
to pass over with the vapour of ammonia, the strongalkaline solution already formed is removed; thatwhich is collected afterwards, by continuing the dis-tillation, is weak or impure, and is returned to theboiler, with a second charge of lime and crude liquor,to undergo another distillation. The first portionfrom the previous operation is introduced into theretort, mixed with a small quantity of lime if neces-sary, and as soon as the disengaged vapour carriessteam with it, the strong liquor in the condenser isto be drawn off as before. The distillation is con-tinued as long as it yields ammonia, and this second-ary product is returned to the retort as before.The first portion of the second distillation is a con-centrated liquid of sufficient purity for all ordinarypurposes of scouring, cleaning, &c., but it may bestill further improved by distilling a third time, inthe same way as already directed, observing that theportion of solution which is made by the absorptionof the ammoniacal gas is preserved, and the residuetransferred again to the retort.
A great step in advance in the manufacture ofammonia on the large scale, was made by Newtonin 1841; it consisted in the application of Cof-fey’s still, described at page 80, but with afew modifications to adapt it to the distillationof the gas water. By its use the ammonia maybe produced of any density up to its most con-centrated state, and consequently of correspondingpurity. Having made the reader already acquaintedwith the still in its application to the whisky trade,it will be unnecessary to enter into lengtheneddetails; those specific alterations which are peculiarlyrequired by the operation will, however, be pointedout. The number of diaphragms in the apparatusis increased or diminished according to the strengthof the product which is to be produced, and thewhole apparatus may be constructed of wood linedwith sheet lead, having the diaphragm plates in theinterior of the analyzing column formed of perforatedsheet-iron. Each of the sheets is supplied withseveral small valves, so weighted as to open upwardswhenever the elastic vapour below the plate exertsmore than a certain amount of pressure upon them.The ammoniacal crude liquid, which enters at thetop, passes downwards through each diaphragm suc-cessively, by means of a pipe rising about 1 inchabove the level of the plate, the lower end of whichis encased in a cup fixed upon the next diaphragm.The pipe must be sufficiently capacious to carry offall the liquid which enters at the top; and as thesolution descends it fills the small cup, and preventsthe vapour from ascending at this part of the plate.Steam, as usual, is the medium which effects theelimination of the volatile body. According as theanimonia is to be procured, the supply of liquor andthe entrance of steam beneath are regulated. Whenit is necessary that the ammonia should depart fromthe top of the rectifying column in the form of gas,the flow of liquid should be in proportion to theascending steam, in order that the liquor in the topdiaphragms may remain at little more than the nor-mal temperature of the atmosphere, but become