2 Pharmaceutical Preparations. Part III.

with it, it is lefs fubject to thisrarefaction, and the fire may beraifed fomewhat more expediti-oufly; though this little advan-tage is perhaps more than counter-balanced by the room which theland takes up in the retort.

Oar chemifts generally leavethe receiver unluted, that it maybe occafionally removed as thefait riles and concretes in the neckof the retort, from whence it isevery now and then fcraped outto prevent the oil from carryingit down into the receiver. Whena grofs thick oil begins to arife,and no more fait appears, th:dittillation is ftopt, though itmight, perhaps, be continuedlonger to advantage.

Mr. Pott informs us, (in acurious diiTertation on the fait ofamber, publiihed in the ninthvolume of the Memoirs of theacademy of fciences of Berlin)that the Pruflian workmen, whoprepare large quantities of the faitfor exportation, from cuttings an.,fmall pieces of amber, performthe difillarion without any inte;medium, and in an open fire :that fweeping out the lalt fromthe neck of the retort being foundtoo troublefome, they fuller theoil to carrv it down into the re-ceiver, and afterward.- feparate itby means of bibulous paper, whichimbibes the oil, and leaves thefait dry; which paper is after-wards fqueezed and dilii'led : thatthey continue the diltiilation tillall that can be forced over hasarifen, with care only to catch thelait thick oil in a feparate re-ceiver ; and that from this theyextraft a confiderable quantitv offait, by (baking it in a ftrong veffelwith three or fouf frelh portionsof hot water, and evaporatingand cryftaliizing the filtered wa-ters.

The fpirit of amber fo called,is no more than a folution of afmall portion of the fait in phlegmor water; and therefore is veryproperly employed for dilfolving'the fait in order to its cryltalliza-tion.

The fait, freed from as muchof the oil as fpongy paper willimbibe, retains fo much as to ap-pear of a dark brown colour.Mr. Pott fays, the method he hasfound to fucceed belt, and withlealt lofs, is, to difi'olve the faitin hot water, and put into thepaper, through which the folutionis to be filtered, a little cottonflightly moiflened with oil of am-ber : this, he fays, detains a e;ooddeal of the oil of the fait, andthe folution paffes through the;more yure. The liquor beingevaporated with a very gentle fire,as that of a water-bath, and fetto flioot, the firlt cryltals provetranfparent, with a flight yellowifhtinge; but thofe which followare brown, oily, and bitter, andare therefore to be further depu-rated in the fame manner. Thewhole quantity of cryltals amountsto about one-thirtieth of the weightof the crude amber employed.By fublimation from fea fait, as di-rected above, the fait is more per-fefliv and more expeditiously pu-rified : Mr. Pott objedts to fubli-mation, that a part of the fait i sdecompofed by it, a coaly matterbeing left behind, even though thefait was previeufly purified by crv-ftalii?ation : it may be pr^fumed.however, that this coal proceedsrather from the burning of lom eremains of the oiiv matter, thanfrom the decompofition of any part,of the true fait.

Pure fait of amber has a pene-trating, fubaflringent acid talte-It diifolves, both in water andrectified fpirit; though not readily