CAM
CAM
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fpimgy and Very light, and when broken fhowthat they are compofed of fmall cryftallinegrains. The rough camphor is mixed with avery minute quantity of earth, from which bothits colour and a flight grittinefs between the teethare derived.
The purification of crude camphor is an artwhich is carefully kept a fecret by thofe whoare in polTeffion of it. Formerly this procefswas carried on only at Venice, afterwards itwas fuccefsfully practifed in Holland, and at pre-fent large quantities are refined by fome of theEnglifh druggifts. If the crude camphor iscontaminated merely by earthy particles, the pu-rification may be effected by Ample fublimationwithout any addition; but as in fome cafes atleaft, the Dutch are in the practice of mixinglime or chalk in fmall proportions, it is probablethat this addition is found of ufe in keepingdown the oil with which the crude camphor isfometimes mingled. Spirit of wine has beenpropofed and employed on a fmall fcale for thepurification of camphor, but this menftruum be-fides being fomewhat expenfive, is incapableof feparating any refmous fubftance which thecrude article may contain.
Simple fublimed camphor differs from therefined camphor of the fliops in being of a fome-what fpungy granular confiftence, but it maybe made to affume the clofe and foliated textureof the latter by fufion, which is underflood tobe the method praftifed in the refineries: thismay be done either by increafing the heat fud-denly when the fublimation is almoft ended,without transferring the camphor to differentveffels, or by melting the fublimed flowers in aveffel for that purpofe.
Although the camphor of commerce is ob-tained only from the Laurus Camphora, and akindred fpecies in Japan , yet its exiftence hasbeen proved in many other fpecies of Lauri;thus the roots of the Cinnamon tree (LaurusCinnamomum J of the Saffafras (Laurus Safafras)of the Cafiia (Laurus Gaflia) may be made toyield real camphor by diftillation, though not infufficient quantities to counterbalance the ex-pence. The diftilled water from the flowers ofthe Anemone pratenfis has been found to de-pofit cryftals of camphor by long flanding. b Ithas alfo been difeovered in the frefh roots ofGaiangale (Maranta GalangaJ Zedoary (Kamp-peria rotunda and ginger; and in the feeds ofcardamom and long pepper. It is probably con-tained in all the effential oils, and has been ac-tually procured from thofe of juniper, fage,
hyffop, thyme, pepper-mint, rofemary, and la-vender. The depofition of cryftalline grainsfimilar to camphor was firfl obferved by Slariusin fome old oil of cinnamon. Kunkel andLewis confirmed this faff, and fupplied fomeothers of the fame nature; Geoffroy, Cartheu-fer and Gaubius extended their experiments tomoft of the effential oils •, and finally, Prouffchas taken the fubject in hand, and from accu-rate and large experiments has fhown that cam-phor may be profitably prepared from the effen-tial oils in the fouthern countries of Europe .
This eminent chemift having accidentally ob-ferved c that the effential oil of lavender diftilledin Murcia , depofited a large proportion of cam-phor, and that the other oils of this provincewere remarkably fragrant, felected the effentialoils of rofemary, marjoram, fage, and lavender,as the fubjects of the following experiments.Equal portions of the four oils were placed in{hallow earthenware veffels, and expofed to fpon-taneous evaporation at a temperature not ex-ceeding 57 0 of Fahren. and in proportion as thecryftals of camphor were depofited they weretaken out and drained, and kept in well floppedvials: by this Ample procefs the oilof rofemary yielded 6.25 per cent, of camphor
— marjoram- 10.14-of camphor
— fage -21.06 - -
— lavender -25.--—■
The oil of lavender appears to be fully fatu-
rated with camphor; for although when heatedit will take up about -V of its weight more ofthis fubftance, yet by cooling it depofits even alarger quantity than it was made to diflolve.When expofed to fpontaneous evaporation thefirfl filaments of camphor begin to appear inabout twelve hours, and continue to be depofitedtill almoft the whole is evaporated. In the otheroils the cryftals were later in {hooting accordingto their relative proportions of camphor; andwhen about four-fifths of the oil was evaporatedthe refidue became thick, and ceafed to yield anymore cryllals. The camphor produced by eachof the four experiments being dried by flightpreflure between filtering paper was in dry, al-moft pulverulent cryftals, as brilliant, and ahnoitas white as fnow, and fo little of the peculiarodour of the oil remained, that it was by nomeans eafy to afeertain by the fmell alone fromwhat fpecies of oil any particular parcel of cryf-tals was obtained.
The proportion of camphor procurable fromtlxefe oils depends in fome degree on the rateat which the evaporation proceeds, the quantity
* An. de Chim. iv. p, 179.