Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/506

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the animal, is of a roundifti figure ; the diameter of it is about a third part of the length of the rays ; its under fur- face is flat, and its upper convex ; and it is covered, both above and below, with fcalcs, but they are arranged in dif- ferent manners. At the infertion of each of the rays, there is placed a triangular membrane, terminating in a fharp point; and thefe membranes only appear, when the crea- ture is immerfed in water, and moves itfelf about. The common habitation of the fea- Stars, on the rough fhores of the fea;, is no place for thefe tender creatures, every dafh of a wave againft a ftone, if they were in the way, would break off their limbs ; they have the caution, there- fore, to fix their refidencc only in calm places, and where the ihore is covered entirely with a deep fmooth fand. 1 hey are often buried in the fand, and often, when the water has forfaken them, are feen walking Slowly on the fhore ; and in this cafe they ufe their rays as fo many legs. As they divide the body of the fiSh into equal parts, there is no ray before or behind any where, fo that the creature goes with equal eafe to any Me that it likes. The beft motion they are able to make is, however, very flow, and the ground on which they march ought to be very even ; for if they at- tempt to haften their pace, or if they find any thing un- even in their paflhge, one or more of their legs ufually breaks ; and this is the reafon why this fpecies is Seldom found with its rays perfect. They never bury themfelves deep in the fand, but juft get under it, fo as to be covered ; and this they do by advancing two of the rays together, and burrowing carefully with them, and then following them with the reft of the rays and the body. Mem. Acad. Par. 1717.

SOLIFUGA, in natural hiftory. See Solipuga.

SOLIPUGA, in natural hiftory, that name given by the Romans to a (mall venomous infect of the fpider-kind, called by the Greeks heliocentros, both words fignifying an animal which flings moft in the country and feafons where the fun is moft hot. Solinus makes this creature peculiar to Sardinia; but this is contrary to all the accounts given us by the antients. Pliny tells us of its being common in Ethiopia, and that in fome places there the inhabitants had been all killed by the ferpents and folipuga ; and Lucan gives the hiftory of it among the poifonous reptiles of Africa.

Almoft all the hot countries produce this venomous little creature. It lies under the fand, to feize other infects as they go by ; and if it can meet with any uncovered part of a man, will bite him, and the wound will prove very pain- ful and envenomed. It is faid that the bite is absolutely mortal, but probably this is not true. Solinus writes the word folifuga, and fo do many others, erroneoufly deriving the name from its flying from the fun's rays, and burying itfelf in the fand.

Pliny fays that it was an ant of the fhape of a fmall fpidcr, but his accounts of this kind are too confufed to be much depended on. Some of the old commentators wander yet farther from the truth, and call it a kind of fly; but the de- fcriptions of it, by thofe moft to be trufted, make it a fpidcr, and it feems to be that called by Ariftotle phalangium . de&icum, the deadly fpidcr. It is plain that even Pliny, in fome part of his works, has understood the creature to be this phalangium ; for where he has translated the old Creek writers on the fubjeet of the phalangium, he has very fre- quently rendered the word not phalangium, but folipuga : fo that it is wonderful he Should, in other places, treat cf the phalangium, without any mention of the fc lipuga, and of the folipuga, in a different part, as not at all allied to the phalangium. It appears from this, and a great many like things, that Pliny wrote his book at different times, and transcribed his accounts from different authors ; fo that he fometimes forgot what he had before written on the fame fubjeet under a different name,

SOLLECITO, in the Italian mufic, is fometimes ufed to ex- prels that a piece is to be played in a mournful manner, fit to enforce grief upon the hearer ; at other times, that it ought to be done carefully and with exactnefs. Brojjard.

SOLMIZARE, in the Italian mufic. See Solfeggiare.

SOLO, in the Italian mufic, is frequently ufed in pieces con- sisting of feveral parts, to mark thofe that are to perform alone ; as fiauto fob, violino fold.

It is alfo ufed for fenatas compofed for one violin, one Ger- man flute, or other instrument, and a bafs : thus we fay, Garalli's folos, Geminiani's folds, Sec.

When two, or three parts, play or fing feparately from the grand chorus, they are called a dot fo/i, a tre foli, &c. Solo is fometimes denoted by S.

SOLOMON's fea/, a plant, called by authors pslygmatum. See the article Polygonatum.

SOLSEQUIUM, a word ufed by fome chemical writers as a name for fulphur.

SOLOS, 0-0X05, in antiquity, an instrument with which the ex- ercife of the quoit was performed, which fome will have to be diftinguiftied from the difcus, becaufe that was of iron, this of Stone : but others, with more reafon, report that the difference eonfifted in this, viz. that the ^-oAes was

of a fpherical figure, and the difcus broad. Poii:r 3 Archaol Graec. Tom. I. p. 443.

SOLVENTS {Cyd.)— Among the feveral liquors, which are called folvents of the metals, there are fome which entire! diflblve them, others which diSIolve only a part of them Common water is the moil general of all jbhaiis; it rjif folvesall metals by attrition alone. Mercury does not cafilJ diffolve iron, but it readily enough diifolves all other me- tals. Acids in general alio diflblve them all ; but thefe acids being of different natures, fome of them diflblve fome par- ticular metals, and do not touch the reft. The general divifion of the acid fohents is into two kinds, thofe of the nature of aqua fords, and thofe of the nature cf aqua regia. The laft are either the fpirit of fea-falt alone, or any of the other acids, with the. addition of fea-falt, or its diftilled fpirit ; and the firft are fpirit of nitre, and all other mixed menftruums, in which fpirit of nitre makes a part, provided there be no fpirit of fea-falt, or of that fait in fubftance in them. There is alfo a third clafs, befide thefe, of what are called the fimple acids ; thefe are fuch acid liquors as contain neither nitre nor fea-falt, nor any preparation of them ; and of thefe fome are obtained from the animal, fome from the vegetable, and fome from the mineral kingdom. All the fohents cf the aqua rcgia clafs diflblve gold, withcut diflblving filver, and all thofe cf the aqua fcrtis clafs diflblve filver, without touching gold : but the other acid fpirit?, and the aqure regales, and aqua; fortes, all equally diffolve the leifer metals-, if made of a proper degree of Strength for each metal. It was long fuppofed, that mercury was only foluble in the aqua forlis claJs, but Mr. Romberg has proved that the aquse regales will alfo diflblve it ; and the fame ac- curate chemiit has alfo advanced another fact, which more than this contradicts the received opinions: this is, that filver is alfo foluble in aqua regia, if proper circumstances are pb- ferved. The occalion-of his advancing this, was the follow- ing obfervation. He often made his aqua rcgia, by distilling together two parts ofiait-petre, three parts of vitriol, and five parts of fea-falt ; in the distillation he ufed to Separate the phlegm which rofe firft, and keep it in a vial by itfelf, and the fpirit that followed in another. One day having fome gold to diflblve, he by mistake took down the vial which contained the phlegm of the aqua regia inftead of that which contained the Strong Spirit ; he poured on a quantity of this phlegm to the gold, and fet it in a proper heat for two hours, when taking it out, the liquor was found to be tinged yellow, but the gold was not dif- folved. Not recollecting the miitakc, he fuppofed he had taken aqua fortis inftead of the aqua rcgia, and taking out the gold he weighed it, and found it had not loft a grain. On this he put in a piece of filver to the liquor, and placing it again in the fame heat, this metal was foon diflblved into a fort of black mud. In this folution there appeared no- thing of that ebullition, which always attends the diifolving filver in aqua fortis; and Mr. Homberg, furprifed at this, was for repeating the operation ; when pouring the liquor upon fome frefh Silver, it did not appear to diflblve it at all : in enquiring into the caufe of this, he found that the liquor he had taken was not aqua fortis, but the phlegm of aqua regia. On thi.s the event feemed much more remarkable than before, and he repeated the procefs feveral times, and always with the fame fuccefs ; but trying ir. a year after- wards, he found the event exactly contrary, the fame liquor then diflblving gold, and not touching Silver : after this making fome of the phlegm afrefh, he found it would dif- folve filver, and not gold, as in the firft experiment; and this, when it had been kept a year, again changed its na- ture, and would then diflblve gold, and not filver! So that, from the whole, there appear three neceflary circumstances for the making aqua regia diflblve filver ; the firft,. that it be very weak ; the fecond, that it have before had gold in it; and the third, that it be frcfti diftilled. This phlegm of aqua regia is pellucid, and colourlefs as water, before it has been poured upon the gold ; after this it be- comes lightly tinged with yellow, and' when after this it is powered upon the filver, it becomes as black as ink. The folution of iilver, in this menitruum, is very different from that in aqua fortis ; in the laft it is made with great ebul- lition, and the folution, when perfected, is limpid as water ; in the other there is no ebullition, and the folution appears rather a difunion of the parts, for the whole becomes black and turbid, and differs much from a clear folution. Mem. Acad. Par. 1706.

SOLUTION {Cyd.)— Chemical Solution. The great Boer* haave has fummed up the doctrine of chemical folution, by US feveral agents, in the following fuccinct manner.

1. Solution is performed by water, by diluting, infufing, boiling, distilling, mixing, fermenting, putrefying, and Se- parating.

2. With oil, by diluting, infufing, boiling, distilling, mix- ing, Separating, but not" by fermenting, or by putrefying.

3. With fire, by calcining, roafting, burning, melting, (wh- llming, mixing, feparating, and by the promoting Several other operations.

1 ±. With