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ther at the bafe, in the manner of the tiles on a houfe-top. It has alfo been ufed as the name of a peculiar fpecies of ftiell : This is a cordiformis or heart-fhell, whofe fides are re- markably ridg'd in this tranlverfe manner, and at the fame time fo divided longitudinally by feven high ribs running from the apex to the edge, that the whole reprefents a roof of a houfe with the beams and raftors, before covered by the tiling. Hence the French call it Faltiere. Imbricate D-Cwpj Imbricatus calyx, in botany, a term ufed by authors to exprefs the cups of fome of the plants which have compound flowers ; in which the common perianthium, furrounding the whole clufter of flowers, is compofed of feveral feries of fquammae, the exterior of which arc ihort, and the interior longer, but in great part hid under thefe up- per ones.
IMITATION of antlent Gems. See the article Gem.
IMMERSUS Scapula, in anatomy, a name given by Riolanus and fume other authors, to a mufcle fmce called the fuhfca- pularis. See the article Subscapulars.
IMMOBILITY of infants. See the article Infant.
IMPARSONEE, in law, is applied to a parfon that is induc- ted, and in pofieflion of a benefice. Blount.
IMPECCABILES, in church hiftory, a name given to thofe heretics, who boafted that they were impeccable? and that there was no need of repentance : Such were the Gnoftics, Prifcillianifts, &c, Hofm. Lex. in voc.
IMPERATOR, among the Romans, a title of honour given to generals after a victory ; firft by the acclamations of the foldiers, and afterwards confirmed by the fenate. Hofm.Liex. in voc. See the article Acclamation.
- IMPERATORIA, in botany, the name of a genus of plants,
the characters of which are thefe. The flowers ftand in umbels, and are of the rofaceous kind, being compofed of feveral petals, in fome bifid at the ends, and in others whole. Thefe petals are difpofed in a circular order on a cup, wiiich afterwards becomes a fruit, compofed of two flattifh and oval feeds, lightly ftriated and marginated, and ufually call- ing off their coats. To this it may be added, that the leaves are large and alated.
The fpecies of Imperatoria enumerated by Mr. Tournefort, are thefe: i. The common large Imperatoria. 2. The greateft alpine Imperatoria. 3. The common cultivated Im- peratoria, called garden angelica. 4. The great Imperatoria, called arch-angelica. 5. The greater marfli Imperatoria, commonly called the great wild angelica. 6. The Canada Imperatoria, with fhining leaves, called the fhining Canada angelica. And 7. The fine leav'd Pyrenean Imperatoria. 'Tourn. Lift, p. 316.
Imperatoria radix, in the materia medica, the root of the common mafterwort, or Imperatoria major ; a plant kept in gardens with us, but very commonly wild in France, Italy, and Germany. The leaves are large, indented, and of a fine green ; and the flowers fmall and white, and difpofed in umbels, which are fucceeded by feeds, much refembling thofe of angelica. The root mould be chofen very fair and clean, frefh dried, hard to break; of a brown colour without, and a fomewhat greenifh one within ; and of a ftrong fmell, and aromatic tafte. It is ufually long, and of the thicknefs of one's thumb, wrinkled on the furface, and entangled with fibres. It is efteemed cordiac, fudorific and alexipharmic, good againft peftilentia! and malignant difeafes, and againft poifons. A decoction of it in wine, ufed as a gargle, is faid to cure the tooch-ach ; and externally it is much commended for the itch, and other fcabs and ulcers. It is alfo an ingre- dient in fome of the officinal compofitions. Pomet's Hift. of Drugs, p. 44.
This root is likewife good in flatulences ; and if Hojf man's authority may be depended on, it is one of the greateft medicines in the world in colics arifing from windy caufes. The feeds are reckoned by many among the provocatives, and are faid by fome, to be of the very firft clafs of thofe medicines. The roots dried, and given in. powder, are a powerful remedy in obftrudtions of the menfes ; and are of great fervice in afthmatic cafes, tooth-ach, and in many dif- orders in the head. Simon Pauli tells us, that an ointment made of the frefh roots of this plant boiled in lard, is one of the bell remedies known for ring-worms.
IMPERATRIX, in botany, a name given bv fome authors to the meum or fpignel. Ger. Emae, Lid. See the article Meum.
IMPERFECT (CycL)~ Imperfect concord, in mufic. See the article Concord.
IMPERFORATE Anus. See the articles Anus and Infant.
IMPERIAL (Cycl.)— Imperial table, in furveying, an in- ftrument made of brafs, with a box and needle, ftaft", &c. ufed in meafuring land.
Imperial Salt, imperials fal, a term ufed by fome of the old writers to exprefs the common fal gemmae ; and ufed by o- thers for the fal ammoniaaim.
IMPOSSIBLE (Cyrl.) — Impossible quantity, in algebra. See the article RooT^
IMPOSTHUME, or Abscess. See the article Abscess. In opening of Abfceffes, and difcharging their matter, the firft great caution is, that it be not done too foon, that is, before
the matter is arrived at a perfect maturity. Ahfceffes are known to be mature and ripe, when the fwelling that was before hard and firm, feels foft and pliant, turns pale, or of a yellowifh colour, and upon applying the finger, a fluid may be perceived to be lodged within ; and when the pain, red- nefs, heat, and pulfarion of the fwelling are gone oft", either wholly or in part, and the fenfation of a weight or heaviness fiezes the part, inftead of the former fymptoms. When thefe figns appear,' the Abfcefs is to be opened in the moft prominent, or the moft depending part, without delay. For the opening a tumor too foon, is of bad confequence,.yet delaying to open it when really ripe, is always of much worfe; for when the matter is detained longer than it mould be, es- pecially in a large fuppuration, and on a nervous part, th_e cqrrupted matter may corrode the adjacent parts, and pro- duce fiftulse, or a caries of the bones ; or by insinuating itfelf into the fmall veflels, and corrupting fuch parts of the blood as it mixes with, it may excite ill-conditioned fevers ; or laftly, by difturbing the functions of the brains, lungs, liver, or kidneys, it may bring on inflammations and fuppurations in thofe parts, and laftly death itfelf. Sometimes it happens in Abfceffes, that the more fine and fubtile part of the matter perfpires, and only the grofler particles are left behind ; and this gives rife to hard tumors, efpecially in the glandular parts. Since thefe therefore are the confequences it Abjcejfes are not timely opened, the great care is to make uie of the firft proper opportunity of opening the maturated tumor, either by the knife or cauftic. if by inciilon, the furgeon is to grafp the bans of the tumor with one hand, preifing the contained matter outward towards the fkin, that he may avoid. hurting any veffels or nerves in the fubjacent parts ; he is then to make the incifion by the {harp fca/pel, in the fbfteft and moft depending part of the tumor, that the matter mav have the freer exit. When the Abfcefs is large, the fcqlpel is not to be taken out as foon as the opening is made, but the incifion in the fkin is to be farther enlarged with it,, but with great caution, to avoid the nerves and larger vellels, with the mufcles of the fubjacent parts. The Abfcefs being thus opened, the putrid matter is to be let out ; . and when it is glutinous and thick, mult be gently prefs'd forth with the hands. If the quantity of matter contained however be very large, and the patient tremble at the thoughts of the knife, or faints away, . which is fometimes the cafe, the beft way is then to difcharge the matter only in part, and fill up the cavity with lint ; and after the patient has been recovered by fome cordial, to compleat the dreffmg with a plafter, com- prefs, and bandage, leaving the perfect difcharge and clean- fing of it to the next dreffing. When the whole of the matter is difcharg'd, the wound is to be cleanfed, and after- wards farcotic medicines applied till it is incarned, and then itwill cicatrize and clofe externally. Hard tents are on thefe occafions very carefully to be avoided, as they often produce very troublefome ulcers ; foft doffils of lint, are much better for ufe ; the cavity fhould be lightly filled with thefe, and they may be taken out once or twice a day, as the difcharge fhall require. It' the patient be of a tender frame, and can- not bear the knife, the Abfcefs may be opened by a cauftic : Among thefe the moft valuable are thofe made of pot-afhes and lime, or of foap-boilers lees. This is to be, applied to the Abfcefs, either whole or in powder; hut a defen- fative plafter muft firft be applied to the Abfcefs, perforated with an oblong narrow hole, that the cauftic may not fpread itfelf upon the fkin, but only make an opening of a proper fize, aiid in a proper place. Over the cauftic is to be applied a comprefs of lint or linnen, and over that a plafter with a ftill larger comprefs of linnen over it ; and the whole muifc be kept firm by a proper bandage.
Things being thus managed, the patient is to be advifed to reft; and the cauftic muft be lufiered to lie on three, four, five, or fometimes fix hours, in proportion to the thicknefs of the fkin on the part, and the ftrength of the medicine. When this is ta- ken off, if the opening be not large enough, it may be eafily enlarged a little with the fcalpel, or even with a probe, without pain to the patient, and all the matter may have a free paf- fage. As foon as the efchar is formed by the cauftic,. it muft be foftened by applying frefh butter, or the common digeftive ointment or baflhcon, retaining thefe on by a plafter and proper bandage; and when this is loofe or feparated, the cure of the wound is to be carried on exactly as in the Ab- fceffes opened by the knife. The knife however is always greatly .preferable to the cauftic, as it is neater, more fafe, and more expeditious ; and the aperture made by it heals much more evenly, and with a fmallcr cicatrix than that made by a cauftic. Heifter's Surgery, p. 183. Bartholine, in his obfervations, gives us a very remarkable account of the termination of a pleurify by an Abfcefs fituated in the thigh, which when the matter was perfectly formed, difcharged itfelf by urine.
In Abfceffes in ano, Mr. Faget advifes to flit open the intefti- num rectum, whenever it is laid bare by an Abfcefs ; and grVes an example of a cure he made, by cutting away the extremity of this gut, which had been laid bare all round by Abfceffes. See Mem. de L'Acad. de Chirurg. Tom. I,
Mr,
