Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/422

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beautiful than either of the others, is however a very beau- tiful ftone ; it is often found in the rugged fhape of our com- mon flints, though not (infrequently nattifh or roundUh like the reft. It is the largeft of all the cornelians, being found from two to fix inches, and often more in diameter, and is of a very beautiful colour, not a clear white, but with an admixture of blue, bringing it to a fort of pearl colour, and is lefs transparent than either the yellow or the red kind. It is found in the Eaft Indies and in many parts of Europe ; France has afforded very fine pieces of it, and Germany produces it in great abundance ; but the beft next the Orien- tal is that of New Spain. ■ Ibid. p. 461. _ Mr. du Fay, of the academy of feiences of Paris, acci- dentally hit upon a very fine way of turning any part of a red cornelian white, fo as to form veins or clouds of that co- lour at pleafure in it. He bad obferved, that there was a way of making figures in white upon garnets, which was done by engraving the intended figure in the ftone, and then fillinc: up the engraving with the common white ena- mel, which, when polifhed down to the level of the ftone, feemed to make one body with it, and the figure to be natu- rally formed in white in it. Deftrous of trying this experiment on the cornelian, he had one engraved, and filled up the lines with white enamel in powder, then putting it over the fire to melt the enamel, he drew it back feveral times, to fee how the procefs fucceeded, and at length found that this ftone would not bear the neceffary degree of fire for thi ■operation, but would itfelf be calcined and fpoiled before the enamel would run : on this lie fhook out the powder, but was furprized to find the bottom of the engraving had all been tinged white by if, though it had not melted. T'o continue this trial, lie laid fome of the powder enamel on a cornelian that was not engraved, but only the powder was laid on in a certain figure. A frnall degree of heat having been given to this under a muffle in a wind furnace, the .parts of the ftone which had been covered with the powder were found to be white, and the others as red as before the Hone was put into the fire.

It appeared hence, that this coating over a part of the ftone was fufficient to give it a whitenefs by the help of fire 5 but the curious author of this invention did not flop here, he foon found that the matter of the enamel was not neceffary to this change, but that any other denfb fubftance would produce the fameefre£t. The common Spanifh white, and feveral other colours, were found to fucceed very well ; but the beft of all other fubftances, he obferves, is a cokothar of vitriol care- fully prepared ; the finer part of which being fcparated by warning,, and afterwards mixed up with gum water, maybe ufed to draw traces ever (b beautiful, and thefe will be all fliewn in white upon the ftone after it has palled the fire. The different parts of a figure thus delineated will he more or lefs white, as the coat of colour has been laid more or lefs thick upon tlie ftone, fo that there only requires a nice hand to draw figures ever - fo beautifully diverfified, with the fhades of a thicker or a clearer white. The counterpart of this experiment gives alfo very beautiful figures, that is, the covering the whole furfacc of the Hona with a coat of the colour, and then drawing the intended figure or lines cut through this coat; this being done, and the whole let by to dry, when it has afterwards been in the fire, all the fur- face will be found white, except where the lines were cut in, and thefe will all be beautifully red, the colour of the ftone having fuffered no hurt in them. Thus the figure will be expreffed in red upon a white ground, and even the mi- nuteft traces drawn by the point of a fine needle will not be loft. Mem. Acad. Far. Z732.

All ccrncUans are not equally pioper for this purpofe. Thofe of a fine deep red, which are all of one fimple colour, and are commonly called by our jewellers cornelians of the old rock, always fucceed perfectly well, and their natural deep red fhews the white with much beauty. The common pale cornelians always lofe a part of their own colour in the fire ; and the cornelians, which have veins of different co- lours, or fhades of colour, never fucceed well, becaufe every different vein receives the tinge in a different manner. The meaner fort of cornelians are fubject alfo to crack and fly, with the degree of heat neceffary "to this operation ; whereas the finer ftones of the old rock always bear it without hurt. It would fe^m a natural confequence from thefe experiments, that the black agate, the coloured jafpers, and many other of that fort of ftones might fucceed as well in the delineat- ing figures on them ; but Mr. du Fay, after repeated expe- rience, found that the cornelian alone would do. Sarda, in zoology, a name by which fome call the fifh, more ufually known by the name of pelamys or pelamys farda ; a fifh refembling a your.g tunny, but having larger and longer teeth and no fcales. Gefner de Pifc. p. 1151. See the article Pelamys. SARDACHATES, in the natural hiftory of the antients, the name of a fpecies of agate, found frequently at this time on the fhores of rivers in the Eaft-Indies ; and feeming to con- tain an admixture of the matter of the common red corne- lian, is very excellently characterized by the name the undents gave it. It is a very elegant and beautiful fpecies, and is often found

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of a confiderablc fize. It is of a pale whitifh ground, and has no veins or other variegations, except a multitude of minute fpots, of a pale red, and of the maiter of the red cornelian ; thefe are fcattered very fparingly in fome parts of the mafs, but in others they are (o cluttered together, as to make frnall clouds of an elegant red. It is very hard, and is capable of an elegant polifh. Our lapidaries do not much efteem it, but in fome other places it is wrought into toys which are much efteemed. Hill's Hift. of Foil', p. 483. SARDANUS, in zoology, the name of a fifh of the harengi- form kind, caught in the Mediterranean, and common in the markets of Rome and Venice. Its body is broader than that of the pilchard, and its back green ; and the line which runs along the belly is much lefs rough than in that fifti. It is indeed eafy to diftinguifh it from the pilchard, but not fo eafy to fhew in what it differs from the common herring more than in fize. It feems very probable, that it is no diftincl: fpecies of fifh ; but, that the herring, like the pilchard, is always fmaller in the Mediterranean than in the Ocean. mikghbfs Hift. Pifc. p. 225. SARDAR, in the Turkifh military orders, the title of an officer chofen from among the caias of the Janizaries on fome particular occafion, fuch as to head a detachment fent to war, or on any other occafion.

The word is of Perfian origin, and is derived from far, which in the language fignifies a head or chief. This officer is a colonel of a detached body ; he is attended in his expedition by his deputy, and two fecretaries, and his office expires at his return from the bufinefs he was dif- patched on. Pocock's /hgypt. p. 169. SARDELLA, in zoology, a name by winch fome have called the pilchard of the Mediterranean lea, fuppofing it different in fpecies from that of the ocean, but it feems in reality to be no other than the common pilchard, only not growing fo large there as in the Ocean. IVl'dughbfs Hift. Pifc. p. 224.. See the article Pilch ardus. SARDINA, in zoology, a name by which many have diftin- guifbed a fifh of the harengilorm kind, which is in reality, however, no other than a frnall pilchard, the pilchard growing to a larger fize in the Ocean than in the Mediter- ranean, ffillugbbfs Hift. Pifc. p. 224. SeePiLCHARDUs. SARDOA, or Sardoum, in botany, a name given by the antients to the water crowfoot, with jagged leaves, called alfo apiaftrum and ranunculus apii folio, from its leaves re- fembling in fome degree thofc of the fmallage. This has been in all ages characfered as a poifon ; but Pliny has found means to confound this with baum, under the name of apiaftrum, which he fays is fed on by the bees in Italy, but is very well known to be a dangerous poifon in Sardinia. SARDONIA herba, in botany, a name given by many of the antients to the poifonous water ranunculus, which others call apiajfrum, from its having leaves fomewhat refembling fmal- lage ; and our modern botanifts call it the ranunculus palujlris apii folio, or water crowfoot with fmallage leaves. It had the name jardonia from its growing very plentifully in Sardinia. The old Greeks have generally written the name of that ifland Sardonia, not Sardinia; and hence they have called the plant alfo by the fame name. It is branded by all authors, both antient and modern, with the name of a poifon, and we fee that even the cattle will not touch it, though a veryfucculent and well looking herb. SARDONYX, (Cycl.) in natural hiftory, the name of a genus of the femi-pellucid gems, which are confiderably tranfpa- rent, of the true onyx ftrudture, either zoned or tabulated, and are compofed of the true matter of the onyx, varieoatcd with zones of that of the red or yellow cornelian. Of this genus there are four known fpecies. 1. The thin zoned redfardonyx, or whitifh onyx, with thin, fnow white, and red zones ; this is one of the moft beautiful of the femi- pellucid gems. The ground of this is a cryftalline matter, fomewhat whitifh, otherwife very little differing from pme cryftal, either in colour or tranfparence ; and the zones are always extremely fine and flender, and laid with a beautiful regularity over one another ; they are of the true matter of the cornelian, and fume are of the plain red cornelian, others of the white, and others often of a pale flefh colour, made by an admixture of the former two. It is only found in the Eaft Indies, and is greatly valued among our' lapida- ries. Hilts Hift. of Foff. p. 493.

The fecond fpecies is the broad veined red fardonyx, or horny onyx, with red punctated zones. This is a beautiful ftone, though greatly inferior to the former kind. Its ground is of a true horn colour, and much refembles that of many of the agates of the Eaft Indies, and its zones are of the true matter of the red cornelian, but they are broad and coarfe to the naked eye ; and when viewed with a microfcope, or even only attentively examined by the naked eye againft a good light, they are found to be each compofed of a number of thin ones, feparated from each other by narrow zones of the common matter of the ftone, and each compofed of feveral clofe arrangements of fmall red fpots. This- is found in New Spain and in fome parts of Europe, and is fometimes wrought into fnuff- boxes, counters for cards, or other toys ; but is verv little efteemed.

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