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violently with aqua fortb. But what abundantly diftinguifneS i a from all other earths, is, that if a little wetted and drawn over a plate of brafs or copper, fo as to mark a Hue, the mark will, a little after, appear bluifh. This is recorded of
• it fo early as in the writings of Diofcorides, and experiment proves it to be true. It feems plainly owing to an alkaline quality in the earth ; this it plainly manifefts, by its fermenting fo irrongly with acids ; and it is a well known thing, that al- kalies draw a blue tincture from copper. The antients all efteemed it a great medicine, and were parti- cularly careful in their way of preparing it for ufe, by^ frequent warning. It is now unknown in the mops ; but its highly alkaline quality, in which it is fo much fuperior to all the earths now in ufe, might make it worth the bringing into ufe again, and it may ftill be had in its old place, in almoft any quantities.
Eretia Terra alba, in the materia medica, a name by which the antients called the white bole armenic, a (mall quantity of which was alfo found near Eretria. Hill's Hift. of
Fofi; p. 8.
ERGALIA, a word ufed, by the alchemifts, to exprefs that part of their treat'ifes which explains the inftruments employ'd in their operations.
ERGASIMA, a name given by Diofcorides, and other of the antients, to a very foul and coarfe kind of myrrh.
ERGASTERIUM, a word ufed, by the writers in chemiftry, fometimes to exprefs the whole laboratory, and fometimes that part of a furnace on which the bottom of the retort, co- pell, or crucible, is to reft in an operation.
ERGASTIN./E, Efy^j-iva-i, in antiquity, a felec~b number of
' virgins emploved in weaving Minerva's peplos, or robe, which was carried in procemon at the Athenian feftiva! Pa- nathenaa. SeePEPLOs, Suppl. and Panat«en;e, Cycl.
ERGASTULUM, among the antients, a houfe of correction, or work-houfe, where flaves, by the private authority of their matters, were confined, and kept at hard labour, for fome offence. It was likewife called Sophronijlerlum. Hofm. Lex. in voc.
ERGATIA, Epyxlia, in antiquity, a Laconian feftival, in ho- nour of Hercules. Pott. Archaeol. Grseo 1. 2. c. 2C. T. i. p. 394.
ERGOT, in the manege, is a ftub like a piece of foft horn, about the bignefs of a chefnut, placed behind and below the paftern joint, and commonly hid under the tuft of the fetlock. To dij'-ergot, or take it out, is to cleave it to the quick with an inciiion knife, in order to pull up a bladder full of water, that lies covered with the Ergot. This operation is fcarcely practifed at Paris, but in Holland is frequently performed upon all four legs, with intent to prevent watry fores, and foul ulcers.
ERICA, Heath, in botany, the name of a genus of plants, the characters of which are thefe : The flower is of the campani- fdrm kind, and confifts of one leaf, from the bottom of which there arifes a piftil, which finally becomes a fruit, ufually of a roundifh figure, and, when ripe, opening into four parts, and divided into four cells, each of which contains a number of fmall feeds.
The fpecies of Erica, enumerated by Mr. Tournefort, are thefe : i. The common purple-flowered fmooth Heath. 2. The common fmooth Heath, with white flowers. 3. The tamarifk-leav'd hairy Heath. 4. The great coris- leav'd white Heath. 5. The great purple Heath, with longer leaves. 6. The juniper-leav'd many flowered Heath. 7. The foreign ftirubby Heath. 8. The greater Heath, with purplifh green flowers. 9. The great befom Heath, with deciduous leaves. 10. The fquare-Ieav'd blackifh red befom Heafh. II. The dwarf Heath, with a grey bark, and flowers like the arbutus. 12. The dwarf Heath, with a grey bark, and white arbutus-like flowers. 13. The Englifti hairy Heath. 14 The pur pie- flowered three branched Heath. 15. The three-leaved procumbent Heath, with flefh-coloured flowers. 16. The green-flowered procumbent Heath. 17. The procumbent Heath, with pale purple flowers. 18. The great flowered Heath, with myrtle-like leaves, hoary under- neath. 19. The green African Heath, with very narrow and fhort leaves, and cluftcred flowers. 20. The African Heath, with hairy flowers difpofed along the branches. 21. The hoary African Heath, with very narrow leaves. 22. The African Heath, with fhort capillaceous leaves, and roundifh purple flowers. 23. The fmall-leav'd African Heath, with round whitifh flowers. 24. The juniper-leav'd African Heath, with long fpiked flowers. 25. The coris- Icav'd African Heath, with long fpiked flowers. The juni- per-leav'd African Heath, with oblong flowers, difpofed in umbells. 27. The coris-leav'd African Heath, with long purple flowers crowing from the alae of the leaves. 28. The coris-leav'd African Heath, with fhort flowers growing from the ate of the leaves. 29. The bladder flowered coris-leav'd African Heath. Toum. Inft. p. 602.
Erica Marina, Sea Heath, a name given, by many authors, to a very beautiful fea plant, of the fucus kind, called by Mr. Ray, and fome others, fucus erica folio. This differs fo much in bignefs, in different places, that it has been fu-
4
fpccled to be of two diftincT: fpecies j thofe plants of tt which are found about the fliore feldom exceeding ten inches in length, and thofe in deeper water often growing to three foot. It is compofed of a vaft number of ramifications ; the bottom ffalk is woody, and often of the thicknefs of a man's little finger, yet even in thefe there is no diftinclion of nerves or fibres, the large branches are rough and knotty, and fend ofFmany other ramifications, the, larger of which are round, but the extream ones flat.
At different fpaces over this plant, one obferves certain knots, or tumours ; thefe are no other than the branch in that part fwell'd, and the ufe of the fwelling is to contain the capfules which enclofe the feed ; thefe, and their arrangement in thefe fwellings, are wholly like thofe of the .common fucus, and there are ufually ten or twelve capfules contained in every fwelling, or bladder of the flalk. They are not arranged in any regularity in the fwelling, but are always found nearer the upper than the lower extremity of it. The feeds are round, and a very great number of them are contained in every capfule.
The fwellings which contain thefe capfules, are fometimes placed at confiderable diftances from one another on the ftalks of the plant, and fometimes they ftand fo elofe, as to reprefent the beads of a necklace. Some branches of the plant alfo are very full of them, and others fcarce have any at all upon them. Sometimes the bladders are found empty on this plant, as they are in the common fea wrack ; but, in this cafe, there may always be feen the marks of the places where the capfules have once been, though fince pe- nfhed by fome accident. Mr. Reaumur, who gives this de- Icription of this plant, never faw its flowers ; but there ieems no doubt but that they are compofed of fhort filaments, like thofe of the other plants of this kind ; and his not examining the plant at a proper feafon, was , probably the reafon of his not finding them, for the flowers and feeds of thefe plants are ufually both large enough to be feen by the naked eye ; and when the feed is fo in molt cafes, the flower is alfo. Mem. Acad, Par. 17 12.
Erica, in ichthyology, a name given by Gaza, and fome others, as the interpretation of the chalcis of Ariftotle, that is, as the name of the common herring.
ERICERUM, a name given by Aerius, and other authors, to a fort of collyrium, ufed in weaknclles of the eyes, in which the herb erica, or heath, was an ingredient.
ERIGERUM, or Senecio, Groundjel y beat into a very coarfe pulp, and applied cold to the pit of the ftomach, has had very good fuccefs in curing of agues. It is to be ufed only on the days free from the fit. It vomits ftrongly fome hours after application. See Medic. ElT. Edinb. Vol. 2. art. 5. or Abridg. Vol. I. p. 203. See Senecio.
ERINACEA, in botany, the name of a genus of plants, the characters of which are thefe : The flowers and fruit are the fame with thofe of the broome ; but the whole plant is fo be- fet with prickles, as to refemble a hedgehog. Toum. Inft. p. 646.
The fpecies of Erinacea, enumerated by Mr. Tournefort, are thefe : 1. The Spanifh Erinacea, with bluifh purple flowers, and 2. The Cretic Erinacea, called, by fome, the Cretic tragacanth.
ERINACEUS, in zoology, the name of the common hedge- hog. The head and fnout of this animal refemble thofe of a hog, but the noftrils, and extremity of the fnout, have more refemblance to thofe of a dog ; the ears are very broad, and like thofe of the moufe kind, and its eyes are fmall and pro- minent. Its legs refemble thofe of the dog, and each foot has five toes, all armed with fharp claws ; of thefe the hinder is fhorter than the reft. Its head, back, and fides, are co- vered with fbarp fpines, and its belly, throat, and legs, with foft white hair.
Authors defcribe two fpecies of hedgehog, the one the ca- nine, or dog kind, the other the hog kind. In England we
' have only the canine kind, which is the above defcribed ; and Mr. Ray much queftions whether there be any other kind in being. Ray's Syn. Quad. p. 231.
In the Linnasan fyftem of zoology, the Hedgehog makes a diftinit genus of animals, in which the author includes the armadillos. The characters of the animals of this clafs are thefe : They have eight paps, two of which are fituated on the breaft, and the other fix on the belly ; and their body is cloathed or defended with a fort of armour. Linnai Syftem. Naturae, p. 37.
Erinaceus is alfo a name given by Dillenius, and fome other botanifts, to the pectinated agarics, called, by others, hydna. Thefe differ from the agarics, properly fo called, which are Iamellated underneath, and from the others, which are porous, for thefe arc echinated, or befet with pointed prickles.
ERINOPTERUS, the Privet Fly, in natural hiftory, the name of a fmall fpecies of fly, which is all over of a filver colour, and of a dufty appearance. It looks, as it fits, like a, fragment of a white feather. Its wings are divided into feve- ral long fegments, like thofe of birds feathers, and feem, in the fame manner, compofed of long feathers, tho* that is not
really
