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The dwarf I^rench (tone Iris. 73. The broad-leaved low ftone Iris. 74.. The larger leaf-lefs ftone low Iris. Tourn. Inft. p. 360.
The Florentine dry Iris, or orrice root, is an expectorant and attenuant. It is given with fuccefs in afthmas, and many other diforders of the brealt and lungs. The dofe is from ten to fifteen grains in powder. The juice of the frefh root of our Iris t is an excellent medicine in dropfies ; and the beft way of giving it is with white wine, an ounce or two for the dofe, which muft be taken every two or three days* It works both by vomit and ftool, and difcharges a very great quantity of phlegm.
We have a great many fpecies of this plant preferred in gar- dens, and moft of them very beautiful ; their roots are tu- berous, and increafe very fail, and all the fpecies are ealiiy propagated by parting them. The bell feafon fordoing which, is in Auguft, when their flower leaves are decayed, and the whole plant begins to change colour; but this mould always be done when the weather is moift, fo that if the month of Auguft mould prove very dry, it mould be deferred till Sep- tember, though it is beft to do it fooner if it can be. They all love a ihady and moift place. If too much dung is ufed to the ground, it rots their roots ; and if they ftand expofed to the fun, their flowers are but of very fhort duration. They fliould be taken up once in two years, to prevent their ex- tending their roots too far, for they are very apt to fpread, and to harbour all forts of vermin.
The curious may raife the feveral fpecies from their feeds, which if taken from the choiceft flowers, and cultivated with care, ufually afford a fine variety in the flowers of the plants they produce. They fliould be fown foon after they are ripe on an eaft border ; they will come up in fpring, and the year following will flower. Miller's Gard, Diet,
Iris lutea palujlris , tins yellow flag flower. The common peo- ple of Scotland have found out a ui'n of this plant, which has efcaped the moft accurate writers on botany. In that coun- try the common ink is made of it. They cut fome of thefe roots into thin flices, and either boil or infufe them in water till the liquor is highly tinged with them ; they then pour it clear off; and then putting into it the blade of a knife, or any other piece of iron, they rub it hard with a rough white pebble common there, and by degrees the liquor becomes black ; they continue rubbing it till it is as deep a black as they require, and it is a tolerable good ink. Philof. Tranf. N° 117.
The juice of this plant mixed with fyrup of buckthorn, is reckoned an effectual hydragogue. See Med. EfT. Edinb. vol. 5. art. 8.
Iris is alfo a name given by fome authors to a peculiar fpecies of fpring cryftal, remarkable for its giving the rain- bow colours in reflection. This, however, being a pro- perty more or loft found in all the kinds of fprig cryftal, and thefe much refembling one another, it became applied to fprig cryftal in general ; and Jriij inftead of being the name of a peculiar fpecies, was underftood as a fynonymous term for common cryftal. Dr. Hill has, however, from the ac- counts of the authors who firft gave a name to this body, afcertained it to be properly the denomination of a peculiar ipecies of fprig cryftal, which he has diftinguifhed by the name ellipomacroflylum albidnm, -pyramids longijfima, or whi- tifh fprig cryftal, with a very long pyramid, which is found in great abundance in Germany, Italy, and England, adhe- ring; to the furfaces of fuTures in ftone quarries. Hill's Hift. of Foil", p. 179.
Iris Marina, the Sea Rainbow. This elegant appearance is generally fecn after a violent ftorm, in which the fea-water has been in vaft emotions. The celeftial rainbow has great advantage over the marine one in the brightnefs and variety of the colours, arid in their diftindtnefs one from the other; for in the fea rainbow there are fcarce any other colours than a dufky yellow on the part toward the fun, and a pale green on the oppofite fide. The other colours are not fo bright or fo diftinct as to be well determined, but the fea rainbows are more frequent and more numerous than the others. It is not uncommon to fee twenty or thirty of them at a time at noon-day. Obferv. fur 1'Afie, p. 292.
IRON {Cyd.) — It would fcarce have been believed, till expe- riments confirmed it, that Iron makes a part of almoft all forts of fubftances. Mr. Gcoffroy attempting to produce Iron by cheiniftry out of feveral ingredients, into which it may be decompofed, wanted firft to find fuch as in themfelves contained no Iron. He found that the afties of all vegetable bodies whatever, contained more or lefs of that metal ; and Mr. Lemeri afterwards, in his analyfis of honey, found Iron in the calcined caput mortuum of that fubftance, many par- ticles of it adhering to a knife that had been touched on a magnet. Mem. Acad. Par. 1706.
This had much puzzled the thoughts of the chemifts, when Mr. Lemeri at length attempted to account for it in this manner. All earth is impregnated with a ferrugineous or vi- triolic matter, and this therefore muft be received into the roots of plants in their growth, and make a part of their fub- ftances. It is, however, in too fmall a quantity, and in par- ticles too much diffeminated, to fliew itfelf in the ftalks or Supfi. Vol. I.
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leaves of the plant ; but when the whole has been calcined, the fire collecting together its feparated particles, they then! form fmall mafles which aft as Iron, and apply themfelves to the magnet.
Befides this, the fame author gives another explication of this phenomenon, according to which he fuppoles that there was abfolutely no Iron in the plant itfelf in its natural ftate, hut that the lire in calcining the afhes, has converted a part of them into that metal.
The firft of thefe has the faireft appearance of truth, but be- fore jt can be determined with any degree of certainty which, or if either be right, it feems neceflary to be perfectly in- formed whether there may not be in nature other particles of matter, belide thofe of Iran, capable of being attracted by the magnet. This, however, there feems at "prefent no po- sitive argument to fupport, or reafon to fuppofe ; and on the other hand, it is not only in all vegetable aihes that particles of Iron are difcovered by the magnet, but in animal ones ; the afhes of caftor having been found by the younger Lemery to contain alfo Iron in as large a proportion as thofe of honey and of vegetables.
To try whether thefe particles attra3ed by the magnet in the afhes of vegetables were really Iron, this author collefled a fmall quantity of them together by means of a knife touched on the magnet, and expofing them to the focus of the great burning-glafs belonging to the then duke of Orleans, "they were found to be melted by that heat in the fame manner as common Iron, and to be attended with all the fame circum- stances in the feveral ftates of fufion and diflipation. It fparkled greatly while foft, and finally was reduced to a fer- rugineous earth or bole, in all refpeels the fame with that feparated by the fame means from filings of Iron, or from the magnet. When this matter is thus proved to be real Iron, the doubt how it is able to get into the minute vef- fels of plants, is cleared, by confidering that Iron is not only prefent in all earth, but is alfo very eafily diffolved by all forts of fate, and takes different forms with every one, according to its feveral nature. When it is found in earths which con- tain an acid analogous to that of vitriol, fulphur, or alum, it becomes converted into a fait known by the name of vi- triol ; and what objection can there be againft the fuppofing that this fait, when diffolved in a fufEcient quantity of wa- ter, is received into the veffels of plants growing in the earth where it abounds ; and we cannot doubt the divifibility of the particles of Iron in the ftate of this fait, being great enough to make it capable of pairing even into the moft mi- nute veflels of plants, when we confider that a grain of vitriol diffolved in nine thoufand times its own weight of water, is capable of giving colour to the whole, and with it a fenfible tafte of the metal from which it had its origin. The fpecific gravity of Iron has been by fome fuppofed to btf a reafon againft the believing its afcent in the veffels of plants; but this appears of no weight, when we confider that all flowers are found, on a chemical analyfis, to contain earth, and that earth is heavier than Iron in the ftate of vi- triol ; and that the metals in the ftate of vitriols, do often rife in vapour, and that without any great heat, is plain from this experiment, that if blue, green, and white vitriol be put together into a box, and covered down, the natural evaporations of each failing confufedly on the others, will change the colour of every one on their upper furface, while that which touches the bottom oi the box remains unaltered. If vitriol be put into an earthen veffel, and water poured on it in fmall quantity only to moiften it, the Iron loaded with its acids, will be found in a little time to afcend up the fides of the pot to the top. This is a fecond proof that Iron in the ftate of vitriol is to be raifed or fublimed with great eafe. There is, however, befides thefe, yet another more convin- cing.
When fpirit of nitre is poured upon filings of Iron, there arifes an ebullition attended with fo great heat that the hand can fcarce be held upon the outfide of the veffel. After the ebullition the liquor becomes red, and greatly loaded with the diffQlved Iron. If oil of tartar be added to this liquor, there is raifed a moderate ebullition, and the mixture fwells greatly. After this there arc found a number of branches very beautifully arranged on the fides of the veffel, and thefe continue to form themfelves under the eye, while there is-no fermentation nor ebullition in the liquor. Thefe curious figures at length cover the whole furface of the veffel, and riling over the rim of it, fall on the outfide, and cover that, alfo. This beautiful vegetation may be varied a great many ways by the different proportions of the ingredients ; but in every procefs it {hews how very eafily Iron may be made to afcend upwards, and that to great heights j and when we confider the power of the heat of the fun, and of the fudhon of the roots of plants, which are in a manner fo many fyphons acting together upon the juices of an earth, among which there are particles of Iron thus diffolved ; we are not to won- der that Iron is conveyed into the veffels of the plant, or found afterwards in its afhes. The wonder would be, that there fhould be any vegetable afhes which did not afford Iron, but that does not appear yet to have been found in regard to any. ^lem. Acad. Par. 1706.
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