Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/387

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cold water, out of (even that were tried one only fucceeded, the reft all cracking and breaking to pieces ; and it was ob- ferved, in this experiment, that at the firft falling of" the drop into the water, and for fome time after, while the red heat lafted, red fparks were mot forth from the drops into the wa- ter ; and that at the inftant of the eruption of thofe particles, and of the bubbles which manifeftly break out of it into the water, it not only cracks, and that fometimes with a consider- able noife, but the body moves and leaps about, and that as well in thofe which fiicceed as thofe that break in the water. A blow with a finall hammer, or other hard body, will not break one of thefe glafs drops if ftruck upon the body j but if the tip only of the neck be broke off, it flies to fmall par- ticles, which eafily crumble into duff ; and if it be broken, when the particles have liberty to difperfe themfelves, they will fly every way in an orb, in the manner of a granado. If they are ground down ever fo low into the body with wa- ter and emery they do not fly; but rubbed on a dry tile, they ufually fly to pieces as foon as the bottom is a little flatted, though fometimes they bear rubbing away deeper ; and fome, when rubbed half down, have been laid by without burfting, and have flown to pieces a little while after without being touched.

If one of them be broken in the hand under water, it ftrikes it more fmartly than if in the open air ; and if it be broken near the furface of the water, the particles it flies into du not dif- perfe themfelves into an orb as in the air, but all fall regu- larly and evenly to the bottom ; and they burft in the fame manner in the exhauffed receiver of the air pump as in the open air. One of thefe drops being fattened into a cement, all but a part of the neck, and then the tip of it broken off, it made a pretty fmart noife, but not fo great as if broken in the hand ; and though, on examining, it appeared to be all fhivered to pieces within, and its colour turned greyifh ; yet the outfide remained fmooth, though cracked, and being taken in pieces, the parts of it rofe like thofe of the flaky bodies, talc, or the like ; the flakes were many of them conical in fhape, and were alfo cracked, that they eafily fell into duff.

Another drop fattened into a ball of cement of half an inch in thicknefs upon the breaking off the tip of it, burff the ball in pieces like a granado. And when attempted to be bored by a lapidary as they bore pearls, they fly to pieces as foon as the tool enters them, in the fame manner as they do when the tip is broken off,

Thefe were the feveral experiments tried on them by the gentlemen of the royal fociety, and thefe all tend to prove the before-mentioned account of their burffing to be true ; and indeed none more than the dry and wet grinding of them ; the wet emery, in the latter cafe, making a co:tt in the place of that it wore away ; and the dry powder of tile in the former, fcarce anfwering the fame purpofe, and at beft but very imperfectly, and preftrving the body together only for a fmall time. Neri's Art of Glafs, p. 362. RUPICAPRA, in natural hiffory, the name of a creature of the goat kind, from whofefkin the chamois leather is made, the creature itfelf being called alfo the chamois by the French, and by theGermans thegemp. See Tab. of Quadrupeds, N"° 8. It is very common in the mountains of Helvetia, and in many other places. In the figure of its body it ("terns to approach very much to the (big kind ; its belly, forehead, inner part of its ears and throat arc white ; it has a yellow ftreak on each fide near the eyes, and the reft of the body is perfectly black ; its tail alfo is black, and that equally on all fides, not white on that part next the body as is the cafe in the deer. Ray's Syn. Quad. p. 78.

The male and female both have horns, which arc a hand's breadth and an half long, rough toward the bottom, and fomewhat knotty ; a new- knot growing every year ; they are nearly ftrait, but at the top bent into the fhape of a hook, black, and not fmooth, but longitudinally firiated with {len- der ftreaks, and their inner cavity is filled up with a fohd bone proceeding from the ficull.

This creature has two remarkable holes always open behind its ears: thefe fome have imagined ferved for refpiration ; and Appian, who had the poetica liuntia for whatever he chofc to fay, feems to have led them into this; but there is no fort of probability of truth in it, fince the fkull is feen immediately under thefe holes, and there is no perfora- tion through it, nor any duel: difcoverable from them. The vulgar have alfo fome remarkable opinions founded on the ftruclure of the horns of this creature; the one, that in de- preffingthem to rub his back, he often gets them fo far within thcikin that he cannot get them out again; and the other that he hangs by his horns to the rocks.

Rl/pm ANT ' a name given to the Donatifts - Scc Campit.*.

K-Url IA, in botany, the name given by Linngeus to a genus « plants, called by Micheli buccaferrm. The characters are thefe. The cup is compofed of a fubulated' (padix, itrait, and of a very fimple ftruclure, which becomes a little bent when the fruit is ripe, and is doubly befet with fru&i- ncations. There are no petals, nor any ffamina, but a number of k,dncy fhaped anthers placed on each fide. The p.ltils arc feveral flender capillary ffyl cs, each bearing an Suppl. Vol. II. J *

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an oval germen with a fimple ftigma. The fruit is an oval, pointed, thin capfule or cortex placed on the ffyle, which becomes elongated. There are as many of thefe as there were piftils on the plant, and each contains one roundifh feed. Unnai Gen. PI. 442. Mkhch 35. RUSCUS, in botany, the name of a genus of plants, called in Englifh butchers broom. The characters of the genus are thefe. The flower confifts of only one leaf, and is of the glubofe cam paniform kind or hollow, with the belly or body larger than the rim. This is inclofed in a cup, divided into many fegments, and from the bafe of it rifes a piftil, which ripens into roundifh foft fruit, containing one or two feeds which are ufually very hard.

There are four fpecies of this plant. 1. The common myr- tle leaved kind. 2. The broad leaved one with the flowers and fruit growing to the leaves called the Alexandrian bay. 3. The narrow leaved one with the fruit growing to the leaves, called hippcgloffum by authors ; and 4. The narrow leaved kind with the fruit growing on the tops of the branches.

Authors have not been accurate in referring the plants of this genus to their proper name rufius, but the three latter have been called by different writers bippoglojfum, bonifacia, hunts alexandrine chamcedaphrie, laurotaxa, and radix id&Q ; and many of them havej in their defcriptions, mif- taken the calyx of fome fpecies for the flower. Tourn. Inft. P-_79-

1 he root of butchers broom is one of the five aperient ones, and is celebrated by authors as a very powerful attenuant and refolvent. It is good in all chronic cafes, and is fre- quently prefcribed in diet drinks, intended to open obftruc- tions of the vifcera, or to promote urine. RUSH, in botany. See the article Juncus. Petrified Rushes. What is ufually called by this name is a kind of foflile coral. But we have in England alfo another not uncommon fubftance, frequently called by the fame name ; this is an incruftation of fparry matter, in form of a ftony cruft on the outfides of real rujhes ; though, in this cafe, it is no real petrifa&ion, but only a covering of this ftone-like matter. Incruftations and petrifactions are ufually confounded together, and the generality of people do not at- tend to the diftinition, which is, that in a real petrifaction, the ftony matter penetrates the very fubffance cf the bodv, as is the cafe in the petrified wood of Ireland and other places ; whereas in thefe incruftations the fubftance itfelf remains unaltered within, and its outer part alone is covered with the ftony fubftance : this is the cafe with what is called petrified mofs at Scarborough and in other parts of England, and this is the cafe in regard to what we call fometimes pe- trified rujhes. Thefe being water plants, and growing by the fides of fprings, loaded with fpar, often fall in, and be- come covered over with it. We have near Kettering in Northamptonfhire a fpring which does this very quickly : a gentleman who tried the experiment, by putting in fome rujhes, at about thirty yards from the fource, found them in one day covered with a thin fkin of fpar ; but after lying fome months there, it formed itfelf into a cruft of half an inch thick round them ; and was fo hard, that it would not break by being thrown violently on the ground'; but all this while the rujhes were not petrified, but only incrufted. JVoodw. Cat. Foil". Vol. 2. p. 78. Rush gmfs. See the article Juncago.

RUSMA, in natural hiffory, the name given by the eaftern nations to the fubftance, called by the antient Greeks fory. It is properly an ore of vitriol, and is ufed as a depilatory, being mixed with lime. Hill's Hift. of FofT. p. 6. See the article Sory.

Mr. Boyle tells us, he made a fine powder of equal parts of rufma and quick-lime, and letting them foak a little time in water they became a foft pafte, which he fpread on the part he would free from hair ; and after letting this pafte He on ■ about three minutes he wiped it off with a wet cloth, and found the hair taken away by the roots, without any incon- venience to the part. Boyle's Works Abr. Vol. 1. p. x^j. Orpiment and quick-lime is ufed in Europe for a depilatory. See the article Hair, Cycl. RUSSGANGENUM, in natural hiffory, a name given by the people of the Eaft-Indies to a yellow and brafs like foflile fubftance, found in many places there ; it refembles the marcafites, only that on trial it is found to contain very little fulphur : it Is probably an ore of zink. RUST of corn, or blight, in hufbandry, the name given by our farmers to a difeafe in corn and other vegetables, in which their ftalks and leaves feem burnt up, and appear of a fort of rujl colour.

Wheat is blighted at two feafons, firft in the bloffom, and then its generation is prevented, many of the hufks being empty in the ear, and the rudiments of the grains not im- pregnated : fecondly, wheat is blighted when the grains are brought to maturity ; and in this cafe they become light, and are of little value for making of bread, having fcarce any flour in them.

The firft of thefe cannot happen in England from frofts,

becaufe our wheat is not in flower till the month of June ;

M m m but