20-j.

The Materia Medica.

Part II.

lypodii did a;- Herat. Polypody ; theroot [£.]

Polypody is a capillary plant,growing upon old walls, the truncsof decayed trees, &c. that foundupon the oak is generally preferredthough not fcnfil?Iy different fromthe others. The roots are longand flender, of a reddifh browncolour on the outfide, greenifhwithin, full of fmall tubercles,which are refernbled to the feet ofan infeft; whence the name ofthe plant : the tafte of thefe rootsjs fweetilh and naufeous.

Polypody has been employed inmedicine for many ages; neverthe-jefs its virtues remain as yet to bedetermined. The ancients held itto be a powerful purger of melan-cholic humours ; by degrees, itcame to be looked upon as an eva-cuator of all hpjnpurs in general tat length, it v/as fuppofed only togently loofen the belly; and after-wards even this quality was deniedjt :• fucceeding phylicians declaredit to be aflringent; of this numberis Boerhaave, who efteems it mo-derately ftyptic, and antifcorb-utic.Por our own part, we have had nodireft experience of it; nor is itemployed in praftice : it is proba-ble that (as Juncker fuppofes) thefrefti root may loofen the belly>and that it has not tjiis effeft when*i dry.

POLYTRICHUM, videTm-chomanes.

POMPHOLYX: a calx,or flow-ers, of zinc, produced in the fur-naces where copper is made intobrhfs by calamine the ore of zinc.It is found adhering to the coversof the crucibles, &c. either in formof thin crufts, or of a light downymatter, generally of a pure whitecolour, though fometimes yellow-ifh. See Zincvm.

POPULI NiGRZE gemma: : Po-puli nigra C. B. The black pop-lar ; its buds [£,]

The black poplar is a large tree,growing wiid in watery places; itis ealily raifed and very quick ofgrowth. The young buds or ru-diments of the leaves, which ap-pear in the beginning of fpring,abound with a yellow, unctuous,odorous juice. They have hithercto been employed chiefly in anointment, which received its namefrom them ; though they are cer-tainly capable oi heing applied toother purpofes :■ a tin£ture of themmade in rectified fpirit, yieldsupon being infpiflated, a fragrantrefin luperior to many of tholebrought irom abroad.

- PORRt radix: Porri communiscapitati C. B Leeks; the root*This participates of Lhe virtues ofgarlick, from which it differs chief-ly in being much weaker. See thearticle Allium.

PORTULAC^E femen: Portu-laca bortenfis latifoliar J. B. Puri-lane; the feeds

This herb is cultivated in gar-dens for culinary ufes. The feedsare ranked among the leffer coldfeeds, and have fometimes beenemployed in emulfions, and thelike, along with the others of thatclafs.

POTENTILLA, vide Argen-tina.

PRASIUM,videMARRUBiuM.

PRIMUL/E VERIS folia, ra-dix : Primula •veris paliido Jlore ht:-milis Tourn. Primrofe ; the herband root [£.]

This is a low plant, growingwild in woods and hedges, andproducing pale yellow flowers inc the,