SAL

SAL

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The apparatus for colle&ing the foot producedby the combuftion of this fuel, confifts of abrick furnace communicating by a flue 2 inchesin diameter, with a vaulted chamber, alfo ofbrick, from the oppofite extremity of whichthere pafl'es out a flue of the fame diameter asthat already mentioned, terminating in a hori-zontal gallery, at the end of which is thechimney. The furnace is charged with theballs above mentioned, to which is added afomewhat variable proportion of dry bones; andwith thefe materials an incefiant fire is kept upfor from four to fix months. At the expirationof this time, the vaulted chamber and galleryare opened and the foot with which they arelined is fcraped off from the top the fides andfloor, obfervitig to keep the foot from the latterdiftinft from the reft.

The principal new combinations that takeplace in confequence of the combuftion appearto be the following : firft, the pit-coal is relolvedinto gas of various kinds, into empyreumaticoil loaded with finely divided charcoal, and intocarbonated ammonia: the foot forms carbonicacid, and alfo gives out the carbonated ammoniawhich it contained: the bones afford empyreu-matie animal oil and carbonated ammonia ; andthe common fait by the action of the clay is de-compofed, its alkaline bafe remaining united tothe earth, and its acid palling in a gafleous ftateinto the chamber, where it meets with and de-compofes the carbonated ammonia, forming falammoniac. Hence the contents of the footcollected in the chamber are carbonaceous mat-ter, muriat of ammonia, and empyreumaticbituminous oil; the latter of which is particu-larly abundant in the foot that concretes on thefloor.

To feparate the fal ammoniac from the otheringredients fublimation is had recourfe to, andis thus performed. Several egg-fhaped jars,made of earthenware, about 20 in hes high and16 in diameter, with a mouth 2f inches wide,are fixed in a furnace, and as foon as they arebecome moderately warm are charged withfoot, broken into final! pieces, to within threeinches of their mouths; a duly regulated heatis then kept up for 48 hours, in which time thevolatile oil fir-ft rifes and pafl’es out into the air,then the fal ammoniac fublimes and fixes itfelft0 u pper part of the jars, while the earthyand carbonaceous impurities remain at thebottom: the veffels are then broken and thecakes of fait extradled. Fifteen pounds of foot

afford on an average about 5lbs of muriatedammonia. The foot from the floor of thechamber is too much loaded with bitumen toadmit of the fait being extracted from it byAmple fublimation, and the mod economicalway of treating it is to bum it over again, bywhich the bitumen is deltroyed, and the falammoniac mixed with the foot, rifes uninjuredinto the chamber.

The method of carrying on the manufactureof this fait in England, though more compli-cated than the above, is, we apprehend, confide-rably more economical. The following* 1 wasthe acftual pra£tice at a large eftablilhment nearLondon , which was abandoned a few years agoin confequence of Glauber’s fait being fubje£tedto the excife.

The material from which the ammonia wasextracted was bones. Thefe were collectedin the ftreets and from dunghills, chiefly by oldwomen. The bones having been thus procured,were chopped into fmall pieces either by hatchetsor machinery, and then boiled, in order to extractthe greafe or fat and marrow remaining in them,which was fold to the foap-boilers. The boneswere then thrown into a cylindrical iron ftill,about 3 feet in diameter, and 8 or 9 feet long,laid horizontally over a fire-place, fo as to becapable of being made moderately red-hot. Atone end of the cylinder was a mouth about 14inches in diameter, by which the bones wereintroduced, and furnifhed with a cover capableof doling it accurately by the help of a littlelute. From the other end of the cylinder pro-ceeded a call iron pipe, from 6 to 8 inchesin diameter, and 18 or 20 feet long, terminatingin one or more oblong leaden receivers, whichwere kept cool by water, placed in a veffel ofthe fame materials, the bottom of which formedtheir cover, the jun&ure being fecured by lute.Of thefe receivers there were commonly two toeach ftill, or three to two ftills. Every receiverwas about 12 feet long, 1 foot deep, and 14inches wid •, and the refrigeratory which coveredit held about 4 inches in depth of water: at theend the molt remote from the ftill was a pipe,fitted with a wooden plug for the purpoie ofdrawing off the condenfed liquor, and above thiswas a hole through which the gas and incon-denfible vapour palled off into the open air.

A Angle charge of each ftill yielded about36II3S. of impure alkaline liquor, and about3clbs. of black fetid oil floating upon its furface.This latter being Ikimmed off, the alkali waa.

voi.. u.

11 Original Communication.

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