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along with an empyreumatic oil fome cryftal-lized flowers of benzoin. Alcohol difl'olves allthe true ftyrax from the impure mafs. Inflavour and, when pure, in other properties,this refin ltrongly refembles the balfam of Tolu.

Gum Resins. Thefe fubftances, as alreadymentioned under this article, are not entirelyfoluble in either water or pure alcohol, fingly,but compleatly fo in a mixture of the two.Many of them have very ftrong fenfible proper-ties, and they are altogether much more a£livewhen ufed medicinally than the refins. Whenrubbed with water, they form a thick emulfion,from which moft of the refinous part feparatesby repofe.

The gum-refins are principally, though notentirely, ufed in medicine.

17. Afafoetida. This gum-refin is the driedjuice of a large umbelliferous plant, (Ferulaafafoetida,) which grows in the mountains ofPerfia and Arabia. ' It is collected by cuttingthe mature plant a little above the ground,which caufes a quantity of white juice to exfudeon the cut furface of the ftock, that foon con-cretes into a brownifh foft gum. I his isremoved, a frelh furface is made on the (talksby cutting it down for an inch or two, andmore of the juice is collected, till after a timethe whole is exhaufted, and the ftalk dies

Afafoetida is brought to us in irregularmafies moftly of a brownifli colour approachingto red, and involving fmaller lumps that arenearly white. It has a very ftrong fetid fmelllike garlic, extremely permanent and diffufive,its talte is naufeous and bitterifh. If rubbedwith water it entirely refolves into a milkyemulfion, from which after (landing for fometime mod of the refinous part fubfides, leavinga clear fupernatant liquor containing much gumin folution. Pure alcohol difl'olves only therefinous part, and makes a clear yellow folu-tion. Dilute alcohol difl'olves the entire refinand forms a brownifli, rather turbid tin&ure .Water diftilled ofl afafoetida riles ltrongly im-pregnated with its peculiar fmell. A hundredgrains charred by fulphuric acid yield 58 grs.of charcoal.

18. Galbanum is the concrete gummy-rsfinousjuice of an umbelliferous plant of Ethiopia ,

(Bubon gailanum,) and is brought over in palefemi-1ranfpirer,t, foft, tenacious mafles, inter-mixeu witn clear white tears of the lame refin.This juice has a ftrong unpleafant fmell, and abitteruh, warm tafte. When rubbed withwater it diflolves into a milky emulfion, and has

other coemical properties of the gum refins.

19. Gum Ammoniacum, a gum refin broughtfrom the Eaft Indies, cornpoied of fmall whitelumps or tears, more brittle than moft of the othergum-refins, and eafily reduced to fine powderin cold weather. It unites perfectly with waterinto a milky emulfion, and water and alcohol fe-parately dilfolve only a portion of the gum. Itis fometimes employed in a fmall degree in thecompofition of cements and varnifhes. A hun-dred grains charred by fu phuric acid give 58of charcoal.

20. Gpopanax is a ftrong-fmelling gummyrefinous juice procured from the Pajlinacaopopanax, and brought from Turkey and theEaft Indies in fmall round drops or irregularlumps of a reddilh yellow colour. It minglesperfectly with water, and agrees in chemicalproperties with the ether gum refins.

21. Sagapenum, is a fetid gum much refern-bling afafoetida, but weaker in fenfible proper-ties, it is brought from Alexandria, in foftirregular mafies (licking to the fingers whenhandled. In chemical properties it agrees veryclofely with afafoetida.

22. Olibanum . A gum refin brought fromTurkey and the Eaft Indies, in large roundifhlumps, femi-pellucid, and when of the pureftkind, of a flight yellow colour. When chewedit has a bitterifh pungent tafte, and makes thefaliva milky. The fmell is moderately ftrong,and not difagreeable. When laid on a hot ironit burns with a ftrong, penetrating, and ratherfragrant fmell, and is fuppofed to have beenufed by the ancients for incenfe.

23. Gamboge. For a defeription of thisvaluable gum, fee die article Gamboge.

24. Euphorbium is a juice procured from aplant of this name, brought chiefly from Barbary,in drops of an irregular form of a pale yellow,and brittle. This gum-refin has but little fmell,but the tafte is one of the moft biting and acridof any known fubftance, and the effect on theorgans remains for a conliderable time. Itconfifts of about equal parts of gum and refin.

25. Myrrh . This gum-refiti exfudes from atree which grows in Abyfiinia and many partsof Arabia, but is litt’e known. It comes overin rounded pieces of various fize, and (li:lmore varying in colour, confidence, tafte, andfmell. The bed fort is iemi-tranfparent, friable,un£luous to the touch, of an uniform light orreddifli yellow colour, of a ftrong but notungrateful fmell, and a flightly pungent andvery bitter tafte. It burns with, fome difficulty.It compleatly difl'olves in boiling water whenprevioufly pulverized, but on cooling,- a yellow