Platina. It has to gold, it has been called or blanc, or white gold; or cryftal, fome fand of a brownish hue, and fome duft of Platina. from its refractory nature, diabolus metallorum; from fome a dark colour obedient to the magnet, and which feems doubts entertained of its character as a metal, juan blanco, to be fragments of other irregular dark-coloured particles, white jack, white rogue, or white mock metal. It has alfo which refemble pieces of emery or loadftone. Dr Ingen. received the appellation of the eighth metal; and, pro houfz, however, fays, that every particle even of fome fine bably from fome diftrict which affords it, has gotten platina which he examined obeyed the magnet more or the name of platina del Pinto. lefs, excepting fome that were tranfparent and ftony; and that there were all magnets in themselves, or that each of these particles had two poles, which he could change at pleafure by magnetic bars. In about 72 pounds weight of platina which was brought from Spanifh America, M. Magellan found not only a large quantity of ferruginous fand, but many pieces of vege table ftalks, a number of feeds, and fome very small red crystals like rubies. These crystals being fent to M. Achard of Berlin, he tried them as far as their minutenefs and small quantity would permit, and at last concluded that they really were rubies. As for the mer curial globules which are fometimes intermixed with the particles of platina, they are entirely foreign to its mines. They are now generally thought to be part of the mercury that has been employed in amalgamation; and which could not be brought from a place lefs diftant than Guancavelica, about 900 miles from the province of Choco where the platina is found. The first in Europe who mentioned it by its prefent name was Don Antonio Ulloa, a Spanish mathematician, who in 1735 accompanied the French academi cians that were sent by their fovereign to determine the figure of the earth by measuring a degree of the meri dian in Peru. In the relation of his voyage, which was published at Madrid in 1748, he fays, that the golden mines in the territory of Choco had been aban doned on account of platina; which he reprefents as a hard ftone not eafily broken by a blow on the anvil, which could not be fubdued by calcination, and from which the gold could not be extracted without much labour, much expence, and great difficulty. The particular places of Choco where it is found are Novita and Citara; but in what quantity it is there to be met with is not ascertained. The miners, difcover ing at an early period that it was a metal, had begun to employ it in adulterating their gold; and the court of Spain, it is faid, dreading the confequences, took measures not only to prevent its exportation, but partly to conceal the knowledge of it from the world. It is reported in the Chemical Annals for July 1792, that when the gold is brought from Choco to be coined in the two mints of Santa-fe, in that of Bogota and Popayan, the gold undergoes a new examination, the platina that remains is carefully feparated, and being given to officers appointed by the king, they, as foon as á certain quantity is collected, carry it away, and before witneffes throw it into the river Bogota, at two leagues diftance from Santa-fe, or into the Cauca, about one league diftant from Popayan. In the Phyfical Journals for November 1785 we are The heterogeneous fubftances with which the platina This metal, though not under its prefent name, which was first mentioned by Don Ulloa, has perhaps been known in Europe fince 1741. At that period Charles Wood found in Jamaica fome platina which was brought from Carthagena. He even made fome chemical trials of it. Among others, he attempted to cupel it; and obferves, in the account which he gave of it in 1749, that the Spaniards had a method of cafting it into different forts of toys, which are common enough in the Spanish Weft Indies. It was probably, too, imported into Spain foon after its difcovery in America. It is faid that Rudenfchoel carried fome of it from Spain to Stockholm in 1745; and the first important fet of experiments that appeared on the subject were those of Scheffer, one of the members of the Swedish Academy. They were publifhed in 1752; and gave this informa tion, that platina is eafily fufible with arfenic, but when alone remains unchanged by the most violent heat of the furnace. Two years after Dr Lewis published fome papers concerning this metal in the Royal Philofophical Tranfactions of London. This eminent chemift, in the courfe of his experiments, had examined it both in the dry and the wet way; discovered a number of its relative affinities; mixed it in different proportions with different metals; and had fused it with arfenic, though he did not afterwards attempt to feparate them. In 1757 Margraaf published feveral very interesting obfervations about the method of feparating it from the iron which always accompanies it. In 1758 and 1763 Macquer and Beaumé made upon See Che it a confiderable number of experiments together, and mistry, formed of it at last a concave mirror. And it was in 1780 that the Journaux de Phyfique gave an account of the labours of Bergman on the same fubject. 1328a. The platina of which the toys were made in the Spa- Ibid. no 1339 nifh West Indies was found by Dr Lewis to be always-1347. mixed with some other metals. What these particular mixtures were is not well known; but many of the allays formed by Dr Lewis himself have promised to be Platina. both ornamental and ufeful. He found that platina, which is of the whole mafs, will render gold no paler 13 than a guinea, which contains only of filver. He found that copper was much improved by allaying it with platina in certain proportions; and that equal parts of platina and brass formed a compound not fubject to tarnish, and which might be employed with great advantage for the fpeculums of telescopes. Belides allaying it with the different metals, it was an object equally interefting to the chemifts and fociety that platina fhould be obtained pure and unmixed; and that means should be contrived to render it fufible, malleable, and ductile. We are now to fee what the chemifts have done to accomplish thefe ends. They readily faw that it would be neceffary, in the firft place, to bring it to a state of ultimate divifion, and that this fhould be tried in one or other of these two ways; by diffolving it in acids, or by fufing it along with fome other metal; for by itself it had hitherto proved abfo lutely unfufible, except when expofed to the focus of a large burning glafs, or the kindled ftream of dephlogifticated or vital air. Among the methods which they employed to feparate it from gold, the principal were the following: The firft was by uniting the mixture of platina and gold with mercury, and grinding the amalgam for a confiderable time with water; in which procefs the platina was gradually thrown out, and the gold retained by the quickfilver. Another method was by mixing a few drops of a folution of platina with above a hundred times the quantity of a folution of gold, and gradually adding a pure fixed alkaline falt as long as it occafioned any effervefcence or precipitation. The remaining liquor in this cafe was fo yellow, that it has been judged the platina would difcover itfelf, though its proportion had been lefs than a thoufandth part of that of gold. A third mode of feparating platina and gold was that of precipitation, by means of mineral fixed alkali; for when this alkali is mixed with a flution of gold containing platina, the gold alone is precipitated, and all the platina remains diffolved. Another method was by precipitation of the platina with fal ammoniac. For this purpose, to a folution of the metal in aqua regia a fmall quantity of the folution of fal ammoniąc in water was added; and if the gold contained any platina, the liquor inftantly grew turbid, and a fine yellow or reddith precipitate quickly fell to the bottom; if the gold was pure, no precipitation or change of tranfparency enfued. The fifth method of feparation was by means of inflammable liquors. The compound to be examined was diffolved in aqua regia: the folution mingled with twice its quantity or more of rectified fpirit of wine, and the mixture fuffered to ftand for fome days in a glafs flightly covered, the gold rofe to the furface, leaving the platina diffolved. Otherwife, to the folution of the metal in aqua regia about half its quantity of any colourless effential oil was added: the two were fhaken well together, and fuffered to reft; apon which the oil rofe immediately to the furface, carrying the gold with it, and leaving the platina diffolved in the acid under it. Or, the gold was taken up fill more readily and more perfectly by ether, or the etherial spirit of wine. But, after all, the most effectual and advantageous method of feparating platina from gold was founded on a property which gold has, and not glatina, of being capable of precipitation from aqua 1. regia by, martial vitriol; and upon a property which Platina. platina has, and not gold, of being capable of precipitation from aqua regia by fal ammoniac. When there fore we would difcover if gold be allayed with platina, let it be diffolved in aqua regia; and to this folution, which will contain both metals, let fome fal ammoniac diffolved in water be added; upon which the platina will be precipitated in form of a brick-coloured fediment. If, on the other fide, we would know if platina contain any gold, let this platina be diffolved in aqua regia, and to the folution add a folution of martial vitriol in water; upon which the liquor will become turbid, and the gold will form a precipitate which may be cafily feparated by decanting and filtrating the liquor. This property which platina poffeffes of being precipitated by martial vitriol was first discovered by M. Scheffer. With respect to the iron contained among the platina, M. de Buffon feparated, by means of a magnet, fix parts out of feven of a parcel of platina. He diftinguished two different matters in platina; of which one was black, friable, and attractable by magnets; and the other confifted of larger grains, was of a livid white or yellowish colour, much lefs attractable, and was extenfible. Between these two different matters were many intermediate particles, fome partaking more of the former, and fome of the latter. He thought that the black matter was chiefly iron; and fays, that he had obferved a fimilar black powder in many ores of iron. M. Morveau found, that a Pruffian blue could be obtained from the black part of the platina, by pouring upon it fpirit of nitre, and afterwards adding to the folution diluted fome phlogisticated alkali; and that the particles of platina which could not be attracted by magnets, did not by this method show any fign of their containing iron. But the most important difcovery concerning the feparation of platina from other metals was a method of melting it, by which it became a perfect metal, malleable, and denfer than gold. It was in 1773 and 1774 that M. de Lifle effected this, by diffolving crude platina in aqua regia, precipitating it from the acid menftruum by fal ammoniac, and by futing this precipitate, without addition, in a double crucible, expofed to the intense heat of a forge-fire excited by double bellows. M. Mor.. veau has repeated the experiment, and found that he could melt the precipitate with feveral fluxes; he found likewife that by means of white glafs, borax, and charcoal, he could melt even crude platina, and could allay together platina and steel in various proportions. M. de Sickengen was the inventor of another method: he diffolved his platina in aqua regia, and precipitated the iron by the prufliate of potafs. In evaporating this liquor he obtained fmall octaedral crystals of the colour of rubies; which, being exposed to a strong heat, yield ed a metal which bore easily the ftroke of the hammer, which could be readily drawn into wire, and was extremely malleable. In attempting to refine platina by the dry way, cus pellation was a method to which the chemifts early had recourfe; but, notwithstanding their utmost endeavours, it has not been attended with all the fuccefs which could have been wifhed. It was found that the fcorification proceeded as well at the beginning of the operation, as when gold and filver are cupelled: but the cupellation E 2 after Plati a afterwards became more and more difficult; because, as the quantity of lead diminished, the matter became less and lefs fufible, and at last ceased to be fluid, notwithstanding the most violent heat; and also because, when the quantity of platina was greater than that of the lead, this latter metal was protected, and not converted into litharge. Hence the regulus obtained was always darkcoloured, rough, adhering to the cupel, brittle, and weighing more than the platina originally employed, from the lead which remained united with it. Meff. Macquer and Beaumé appear nevertheless to have carried this experiment further: they kept the matter expofed to a violent fire during a longer time; that is, about 50 hours fucceffively and therefore, although their platina was tarnished and rough on its furface, it was internally white and fhining, eafily feparable from the cupel, and a little diminished in weight; a certain proof that no lead remained in it. This platina was alfo ductile, and capable of extenfion under the hammer. Cupellation, therefore, though not the beft, is at leaft a certain method of applying platina to use, and of forming it into utenfils. What has been thought a preferable method, is firft to fufe the platina with arfenic, and afterwards diflipate this laft metal by a strong heat: by this means Achard and Rochon were able to obtain a pure platina; of which the former made fome fmall crucibles, and the latter, by allaying it with copper and tin, fome large mirrors for reflecting telescopes. Jeanety of Paris has gone ftill farther: befides fnuff boxes, watch-chains, and a coffee pot of platina prepared by this artist, the world has feen a lens weighing fix pounds, a ball weighing nine, and two bars 19 feet long, and weighing no lefs than II pounds each. This gentleman has the merit of being the firft who wrought this metal in the great way. The method he employed was far from being new; it had been fuggefted by Scheffer, by Willis, by Margraaf, and was afterwards practised by Achard, Morveau, and a great many others, but who always prepared it in very fmall quantities. In the Chemical Annals for July 1792, the following account of it is given by himself. The platina is first pounded in water to difengage it from the ferruginous and other heterogeneous particles that are mixed with it. "This being done, I take (fays He) one pound and a half of platina, two pounds of white arfenic in powder, and one pound of purified potafh. I mix the whole: I put a crucible in the fire capable of containing about 20 pounds; when my furnace and crucible are well heated, I throw into the crucible one third of the mixture, and apply a good heat; I then add a fecond quantity and a third, and fo on, always ta king care at every time to mix the whole with a rod of platina. I give now a confiderable force to the fire; and when I am certain that the whole is completely in a state of fufion, I withdraw my crucible and leave it to cool. After breaking it, I find a button that is well formed and attractable by the magnet. I bruife this button into fmall pieces, and fufe it a second time in the fame manner: if this fecond fufion, which it generally is, be not sufficient to effect the feparation of the iron from the platina, I fufe it a third time; but if I be obliged to do it a third time, I always put two buttons together, to fave at once a crucible and charcoal. This first operation being finished, I take a crucible with a flat bottom and of a circumference to give to the Platina button about three inches and a quarter in diameter. I make this crucible red hot, and throw into it onepound and a half of the platina which has been already fufed with the arfenic after it was broken into small pieces; to this I add a quantity of arfenic of the fame weight, and about half a pound of refined potash. I give to the fire a confiderable force; and when I am certain that the whole is completely in a state of fufion, 1 withdraw my crucible and leave it to cool, taking care always to place it horizontally, that the button may be of an equal thicknefs. After breaking the crucible, I find a button clear and fonorous, and weighing commonly about 1 pound and 11 ounces. I have remark that in proportion to the quantity of arfenic combined with the platina, the purification always fucceeds with the more or lefs promptnefs and cafe; and the greater the proportion fo much the better. In this state I put my button into a furnace under a muffle, which ought not to be higher than the edge of the button lying on its flat fide, and inclining a little to the walls of the muffle. In this manner I place three buttons on each fide of the muffle, and apply fire to my furnace, that the muffle may be equally heated throughout: as foon as the buttons be gin to evaporate I fhut the doors of my furnace, that the heat may be kept up to the fame degree; this ought always to be carefully attended to even to the end of the operation, for even a temporary excefs of heat might fpoil the whole of my paft operations and render them abortive. I caufe my buttons to volatilize during fix hours, always taking care to change their fituation, that every part may receive an equal portion of heat a I then put them in common oil, and for a like time keep them in a fire fufficient to diffipate the oil in smoke, I continue this operation as long as the button emits vapours; and when the evaporation has ceafed I push the fire as far as it will go by means of the oil. These arfenical vapours have a bright fhining metallic appear ance, which I never can obtain any other way, and withs out which I have never been able to render platina pers fectly malleable. proper "If these steps which are here pointed out be ly followed, the operation lafts only eight days. My buttons are then thrown into the nitrous acid, and ats terwards boiled in diftilled water, till no part of the acid remains with them: I now heap them together one above another, apply the ftrongeft poffible in at, and beat them with a hammer, taking always care at the firft heat tả make them red hot in the crucible, that no foreign bos dies may mix with them, as before this compreffion they are only fo many fpongy maffes. I afterwards heat them in a naked state (les chauffe à nud); and bringing them to a fquare form, I hammer them on all fides for a fhorter or longer time according to their bulk.” Such is the procefs obferved by Jeanety in fufing plaz tina; but he thinks that the working of this metal is fufceptible of ftill greater improvement. In 1788 it was accordingly propofed by fome of the French che mifts to fufe platina by mixing it with charcoal and phofphoric glafs, and afterwards to expofe the phofphure of platina to a heat fufficient to volatilize and dif pate the phofphorus. This method fucceeded remarkably well with M. Pelletier; but, befides being tedious, it is difficult to feparate the laft portions of the phofphorus; and as thefe operations are always coftly, there are few artifts + Clapta!. foret. Plato. Platira, artists who are willing to undertake them. M. de former of thefe confifts of tin alone, the latter ge- Plating, Plating Morveau has alfo fufed platina with his vitreous flux, nerally of three parts of filver and one of brafs. When made of pounded glafs, borax, and charcoal and Beau- a buckle, for instance, is to be plated by means of the mé has advised to fufe it with a flight addition of lead, foft folder, the ring, before it is bent, is first tinned, bifmuth, antimony, or arfenic, and by keeping the alloy and then the filver-plate is gently hammered upon it, in the fire a long time to diffipate the metals which have the hammer employed being always covered with a facilitated the fufion. Platina may likewife be fufed piece of cloth. The filver now forms, as it were, a with a metal foluble in an acid: the mixture being pul- mould to the ring, and whatever of it is not intended verized, the alloyed metal may be diffolyed, and the to be ufed is cut off. This mould is faftened to the powder of platina may then be fufed with the flux of ring of the buckle by two or three cramps of small ironDe Morveau; or, instead of ufing a foluble metal, a cal wire; after which the buckle, with the plated fide cinable metal may be employed, and heated as be- undermoft, is laid upon a plate of iron fufficiently hot to melt the tin, but not the filver. The buckle is then The colour of platina, when properly refined, is fome- covered with powdered refin or anointed with turpenthing between that of iron and filver; it has no finell, and tine; and left there fhould be a deficiency of tin, a is the heaviest body yet known in nature. According to finall portion of rolled tin is likewife melted on it. The Mr Kirwan its fpecific gravity is to that of water as 23 buckle is now taken off with a tongs, and commonly to 1. It may likewife be faid to be the most durable of all laid on a bed of fand, where the plate and the ring, the metals: it is harder than iron; it undergoes no altera- while the folder is yet in a state of fufion, are more tion in the air, and fire alone does not even appear to pof- clofely compreffed by a smart ftroke with a block of fefs the power of changing it; for which reafon it forms wood. The buckle is afterwards bent and finished. the bett of all crucibles that have yet been invented. It refifts the action of acids, alkalis, and fulphurs: it may be rolled into plates as fine as leaves of gold which are ufed in gilding; it is likewife extremely ductile: and Dr Withering tells us, that a wire of platina is ftronger than a wire of gold or of filver of the fame thickness; it is preferable to gold by the property which it has of foldering or welding without mixture; and it unites, fays Chaptal, two qualities never before found in one. and the fame fubftance. When formed into a mirror, it reflects but one image, at the fame time that it is as unchangeable as a mirror of glass. As thofe motives which at first prepoffeffed the court of Spain against this metal no longer exift, it is to be hoped that the decree which was paffed against it will foon be revoked, and that the Spanish monarch will neither defpife fo rich a treasure as his mines of platina, nor refufe to the world the numerous advantages that may be derived from a fubftance that promifes to be of fo much importance in commerce and the arts. PLATING is the art of covering bafer metals with a thin plate of filver either for use or for ornament. It is faid to have been invented by a fpur-maker, not for show but for feal utility. Till then the more elegant fpurs in common ufe were made of folid filver, and from the flexibility of that metal they were liable to be hent into inconvenient forms by the flightet accident. To remedy this defect, a workman at Birmingham contrived to make the branches of a pair of fpurs hollow, and to fill that hollow with a flender rod of fteel or iron. Finding this a great improvement, and being defirous to add cheapnefs to utility, he continued to make the hollow larger, and of courfe the iron thicker and thicker, till at laft he discovered the means of coating an iron fpur with filver in fuch a manner as to make it equally elegant with thofe which were made wholly of that metal. The invention was quickly applied to other purpofes; and to numberlefs utenfils which were formerly made of brafs or iron are now given the ftrength of thefe metals, and the elegance of filver, for a fmall additional expence. The filver plate is generally made to adhere to the bafer metal by means of folder; which is of two kinds, the foft and the bard, or the tin and filver folders. The Sometimes the melted tin is poured into the filver mould, which has been previously rubbed over with fome flux. The buckle ring is then put among the melted tin, and the plating finished. This is called by the workmen filling up. When the hard folder is employed, the procefs is in many refpects different. Before the plate is fitted to the iron or other metal, it is rubbed over with a folution of borax. Stripes of filver are placed along the joinings of the plate; and inftead of two or three cramps, as in the former cafe, the whole is wrapped round with fmall wire; the folder and joinings are again rubbed with the borax, and the whole put into a charcoal fire till the folder be in fufion. When taken out the wire is inflantly removed, the plate is cleaned by the application of fome acid, and afterwards made fmooth by the ftrokes of a hammer. Metal plating is when a bar of filver and copper are taken of at least one equal fide. The equal fides are made fmooth, and the two bars faftened together by wire wrapped round them. These bars are then sweated: in a charcoal fire; and after fweating, they adhere as cloftly together as if they were foldered. After this. they are flattened into a plate between two rollers, when the copper appears on one fide and the filver on the other. This fort of plate is named plated metal. French plating is when filver-leaf is burnished on a piece of metal in a certain degree of heat. When filver is diffolved in aquafortis, and precipita ted upon another metal, the process is called fivering. See SOLDERING. PLATO, an illustrious philosopher of antiquity, was by defcent an Athenian, though the place of his birth was the Ifland of Egina. His lineage through his fa ther is traced back to Codrus the laft king of Athens and through his mother to Solon the celebrated legifla tor. The time of his birth is commonly placed in the beginning of the 88th Olympiad; but Dr Enfield thinks it may be more accurately fixed in the third year of the 87th Olympiad, or 430 years before the Chriftian era He gave early indications of an extensive and original genius, and had an education fuitable to his high rank,, being inftructed in the rudiments of letters by the gram marian Dionyfius, and trained in athletic exercises by Arifto Plato. Arifto of Argos. He applied with great diligence to the study of the arts of painting and poetry; and made fuch proficiency in the latter, as to produce an epic poem, which, upon comparing it with the poems of Homer, he committed to the flames. At the age of 20 he compofed a dramatic piece; but after he had given it to the performers, happening to attend upon a difcourfe of Socrates, he was fo captivated by his eloquence, that he reclaimed his tragedy without fuffering it to be acted, renounced the mufes, burnt all his poems, and applied himself wholly to the study of wisdom. It is thought that Plato's firft mafters in philofophy were Cratylus and Hermogenes, who taught the fyftems of Heraclitus and Parmenides; but when he was 20 years old, he attached himself wholly to Socrates, with whom he remained eight years in the relation of a scholar. During this period, he frequently difpleafed his companions, and fometimes even his mafter, by grafting up. on the Socratic fyftem opinions which were taken from fome other stock. It was the practice of the scholars of Socrates to commit to writing the fubftance of their mafter's discourses. Plato wrote them in the form of dialogues; but with fo great additions of his own, that Socrates, hearing him recite his Lyfis, cried out, "O Hercules!- how many things does this young man feign of me!" Plato, however, retained the warmest attachment to his master. When that great and good man was fummoned before the fenate, his illuftrious fcholar undertook to plead his caufe, and begun a fpeech in his defence; but the partiality and violence of the judges would not permit him to proceed. After the condemnation, he prefented his master with money fufficient to redeem his life; which, however, Socrates refused to accept. During his imprisonment, Plato attended him, and was prefent at a conversation which he held with his friends concerning the immortality of the foul; the fubftance of which he afterwards committed to writing in the beautiful dialogue intitled Phado, not, however, without interweaving his own opinions and language. The philofophers who were at Athens were fo alarmed at the death of Socrates, that most of them fled front the city to avoid the injuftice and cruelty of the government. Plato, whofe grief upon this occafion is faid by Plutarch to have been exceffive, retired to Megara; where he was friendly entertained by Euclid, who had been one of Socrates's first scholars, till the storm was over. Afterwards he determined to travel in purfuit of knowledge; and from Megara he went to Italy, where he conferred with Eurytus, Philolaus, and Archytas. These were the most celebrated of the followers of Pythagoras, whofe doctrine was then become famous in Greece; and from these the Pythagoreaps have affirmed that he had all his natural philofophy. He dived into the most profound and myfterious fecrets of the Pythagoric doctrines; and perceiving other knowledge to be connected with them, he went to Cyrene, where he learned geometry of Theodorus the mathematician. From thence he paffed into Egypt, to acquaint himself with the theology of their priests, to study more nicely the proportions of geometry, and to inftruct himself in aftronomical obfervations; and having taken a full furvey of all the country, he fettled for fome time in the province of Sais, learning of the wife men there, what they held concerning the universe, whether it had a be ginning, whether it moved wholly or in part, &c.; and Plato. Paufanias affirms, that he learned from these the immortality, and alfo the tranfmigration, of fouls. Some of the fathers will have it, that he had communication with the books of Mofes, and that he studied under a learned Jew of Heliopolis; but there is nothing that can be called evidence for these affertions. St Auftin once believed that Plato had fome conference with Jeremiah; but afterwards difcovered, that that prophet must have been dead at least 60 years before Plato's voyage to Egypt. Plato's curiofity was not yet fatisfied. He travelled into Perfia to confult the magi about the religion of that country: and he defigned to have penetrated even to the Indies, and to have learned of the Brachmans their manners and cultoms; but the wars in Afia hindered him. "He then returned into Italy, to the Pythagorean school at Tarentum, where he endeavoured to improve his own fyftem, by incorporating with it the doctrine of Pythagoras, as it was then taught by Archytas, Timæus, and others. And afterwards, when he vifited Sicily, he retained fuch an attachment to the Italic school, that, through the bounty of Dionyfius, he purchafed at a vast price feveral books which contained the doctrine of Pythagoras, from Philolaus, one of his followers. "Returning home richly ftored with knowledge of various kinds, Plato fettled in Athens, and executed the defign, which he had doubtless long had in contemplation, of forming a new school for the inftruction of youth in the principles of philofophy. The place which he made choice of for this purpose was a public grove, called the Academy, from Hecademus, who left it to the citizens for the purpose of gymnastie exercises. Adorned with ftatues, temples, and fepulchres, planted with lofty plane-trees, and interfected by a gentle ftream, it afforded a delightful retreat for philofophy and the mufes. Of this retreat Horace speaks: Atque inter fylvas Academi quærere verum, "Midft Academic groves to fearch for truth." Within this inclosure he poffeffed, as a part of his humble patrimony, purchased at the price of three thousand drachmas, a fmall garden, in which he opened a school for the reception of those who might be inclined to attend his inftructions. How much Plato valued mathematical ftudies, and how neceffary a preparation he thought them for higher fpeculations, appears from the infcription which he placed over the door of his school: ·'Oudeis aytairentes HOITO. "Let no one who is unacquainted with geometry enter here." "This new school foon became famous, and its master was ranked among the most eminent philofophers. His travels into diftant countries, where learning and wifdom flourished, gave him celebrity among his brethren of the Socratic fect. None of thefe had ventured to inftitute, a fehool in Athens except Ariftippus; and he had confined his instructions almost entirely to ethical fubjects,, and had brought himself into some difcredit by the freedom of his manners. Plato alone remained to inherit the patrimony of public esteem which Socrates had left his difciples; and he poffeffed talents and learning adequate to his defign of extending the ftudy of philofophy beyond the limits within which it had been in clofed |