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ed himself of the opportunity to testify his regard for the merit and character of his friend, by conferring upon him the office of secretary for the peace. He was also introduced to the friendship of Lord Parker (afterwards President of the Royal Society) which terminated only with his death, and, amongst other distinguished characters in the annals of science and literature, the names of Sir lsaac Newton, Halley, Mead, and Samuel Johnson, may be enumerated as the intimate friends of Mr. Jones. By Sir Isaac Newton he was treated with particular regard and confidence; and having afterwards found, among some papers of Collins which fell into his hands, a tract of Newton's, entitled “Analysis per quantitatum Series, Fluxiones, ac differentias: cum Enumeratione Linearum tertii Ordines,” with the consent and assistance of that great man, he ushered it into the world, accompanied by other pieces on analytical subjects, in 1711, quarto. . By being thus the means of preserving some of Newton's papers, which might have otherwise been lost, he secured to his friend the honour of having applied the method of infinite series to all sorts of curves, some time before Mercator had published his “Quadrature of the Hyperbola,” by a similar method. And its appearance at a time when the dispute ran high between Leibnitz and the friends of Newton, concerning the invention of fluxions, contributed to the decision of the question in favour of our illustrious countryman. Mr. Jones was elected a member, and afterwards a Vice-President, of the Royal society. After the retirement of Lord Macclesfield to Sherborne Castle, Mr. Jones resided with his lordship as a member of his family, and instructed him in the Sciences. While he was in this situation, he had the misfortune to lose the greatest part of his property, the accumulation of industry and economy, by the failure of a banker; but the friendship of Lord Macclesfield diminished the weight of the loss, by procuring for hitna sinecure place of considerable emolument. From the same nobleman he had the offer of a more lucrative situation; but he declined the acceptance of it, as it required a more close official attendance than was agreeable to his temper, or compatible with his attachment to scientific pursuits. While he was in this situation, also, he entered into a matrimonial connexion, from which sprang three children, the last of whom was the late Sir William

Jones. Mr. Jones survived the birth of this son only three years, being attacked with a disorder, which the sagacity of Dr. Mead, who attended him with the anxiety of an affectionate friend, immediately discovered to be a polypus of the heart, and wholly incurable. He died in July, 1749, when about sixty-nine years of age, leaving behind him a great reputation and moderate property. “The history of men of letters,” says Lord Teignmouth, from whom we have chiefly extracted the preceding particulars, “is too often a melancholy detail of human misery, exhibiting the unavailing struggles of genius and learning against penury, and life consumed in fruitless expectation of patronage and reward. We contemplate with satisfaction the reverse of this picture in the history of Mr. Jones, as we trace him in his progress from obscurity to distinction, and in his participation of the friendship and beneficence of the first characters of the times. Nor is it less grateful to remark, that the attachment of his professed friends did not expire with his life; after a proper interval, they visited his widow, and vied in their offers of service to her: amongst others, to whom she was particularly obliged, I mention with respect Mr. Baker, author of a treatise on the improved microscope, who afforded her important assistance, in arranging the collection of shells, fossils, and other curiosities, left by her deceased husband, and in disposing of them to the best advantage.” Mr. Jones's papers in the Philos. Trans. are, “A Compendious Disposition of Equations for exhibiting the Relations of Goniometrical Lines,” in the forty-fourth volume; “A Tract on Logarithms,” in the sixty-first; “An Account of the Person killed by Lightning in Tottenhamcourt Chapel, and its Effects on the Building,” in the sixty-second ; and “Properties of the Conic Sections, deduced by a Compendious Method,” in the sixtythird volume. These pieces, and indeed all his works, are distinguished by remarkable neatness, brevity, accuracy, and perspicuity. If, however, Mr. Nichols is not deceived in his information, the world has been deprived of his last and most laborious work, which he lived to complete, but not to see it printed. It was a work of the same nature with his “Synopsis,” but far more copious and diffusive, and intended to serve as a general introduction to the sciences, or, which is the same thing, to the mathematical and philosophical works of Newton. A work of this kind was a desideratum in literature, and it required a geometrician of the first class to sustain the weight of so important an undertaking; for which, as D'Alembert justly observes, “the combined force of the greatest mathematicians would not have been more than sufficient.” Mr. Jones was fully aware of the arduous nature of such a task; but the importunity of his numerous acquaintance, and particularly of his friend Lord Macclesfield, induced him to commence, and to persist till he had completed his design, the result of all his knowledge and experience, and, what he had reason to hope, would prove a lasting monument of his talents and industry. Scarcely had he sent the first sheet to the press, when his illness, which proved fatal, obliged him to stop the impression; but before his death he entrusted his M.S. fairly transcribed, to the care of Lord Macclesfield, who promised to publish it, as well for the honour of the author, as the benefit of his family. The Earl survived his friend many years, but the MS. was forgotten or neglected, and after Lord Macclesfield's death was not to be found. Whether it was accidentally destroyed, or whether, as has been suggested, it was lent to some geometrician, who basely concealed it, or possibly burnt the original, to prevent the advantages which he derived from it from detection, cannot now be ascertained. Such is the relation given in the “Anecdotes of Bowyer,” on which Lord Teignmouth remarks, that there is no evidence in the memoranda left by Sir William Jones to confirm or disprove these assertions. Mr. Jones is said to have possessed the best mathematical library in England, containing almost every book of that kind which was to be met with. By a bequest in his will, it became the property of Lord Macclesfield, and forms at present a distinguished part of the Macclesfield collection at Sherborne Castle, in Oxfordshire. He had also collected a great quantity of MS. papers and letters of former mathematicians, which have often proved useful to the writers of their lives, &c. After his death, these were dispersed, and fell into the hands of different persons, and, among others, into those of Mr. Robertson, librarian and clerk to the Royal Society, from whose executors Dr. Hutton purchased a considerable number of them. JONK, or Jonque, in naval affairs, is a kind of small ship, very common in the East Indies: these vessels are about the

bigness of our fly-boats, and differ in the

form of their building, according to the different methods of naval architecture used by the nations to which they belong. Their sails are frequently made of mats, and their anchors are made of wood. JOURNAL, a day-book, register, or account of what passes daily. Joun NAL, or DAY-Book, among merchants, is that wherein the transactions recorded in the waste-book are prepared to be carried to the ledger, by having their proper debtors and creditors ascertained and pointed out. For a more distinct account of which, see Book-keepIng. Joun NAL, at sea, is a register, kept by the pilot and others, wherein notice is taken of every thing that happens to the ship from day to day, with regard to the winds, the rhumbs, the rake, soundings, &c. and in order to enable him to adjust the reckoning, and determine the place where the ship is. In sea journals, the day, or twenty-four hours, terminate at noon, because the errors of the dead reckoning are at that period generally corrected by a solar observation. The first twelve hours, from noon to midnight, are marked with P. M. signifying after mid-day ; and the second twelve hours, from midnight to noon, are marked with A. M. signifying after midnight; so that the ship account is twelve hours earlier than the short account of time. There are various ways of keeping journals, according to the different notions of mariners concerning the articles that are to be entered. Some keep such a kind of journal as is only an abstract of each day’s transactions, specifying the weather, what ships or lands were seen, accidents on board, the latitude, longitude, the meridional distance, course, and run. These particulars are to be drawn from the ship's log-book, or from that kept by the pilot himself. Others keep only one account, including the log-book, and all the work of each day, with the deductions drawn from it. Notwithstanding the form of keeping journals is very different in merchant ships, yet one method appears to be invariably pursued in the navy, which, however, admits of much improvement, for no form can be properly called perfect, that leaves as great a space for one day’s work, which may not be interesting, and can therefore be told in a few lines, as for another, which may probably abound with important incidents, and consequently require much room. According to circumstances, the matter must be greater or less, and the appropriated space should admit of all.

JOURNEWMAN, properly one who works by the day only; but it is now used for any one who works under a master, either by the day, the year, or the piece. JOY, one of the most powerful mental emotions, accompanied with an extraordinary degree of animation and pleasure. The effect of joy, if not too violent, invigorates the whole animal frame. But sudden and excessive joy is often as injurious as the operation of ei her grief or terror, and there are a thousand instances on record, in which the precipitate communication of unexpected good news has proved fatal IPECACUANHA. See MATERIA MEDIC A. IPOMOEA, in botany, a genus of the Pentandria Monogynia class and order. Natural order of Campanaceae. Convolvuli, Jussieu. Essential character: corolla funnel-form; stigma headed globose: capsule three-celled There are twenty-seven species, of which I. quamoclit, wingedleaved ipomoea, is an annual plant, rising with oblong, broad seed leaves, which remain a considerable time before they fall off; stems slender, twining, rising by support to the height of eight feet, sending out several side branches, which twine about each other. The flowers come out singly from the side of the stalks, on slender peduncles, an inch long. The tube of the corolla is about the same length, narrow at bottom, and gradually widening to the top, where it spreads open, flat, with five angles. It is of a beautiful scarlet colour, making a fine appearance. It is a native of both Indies. IRESINE, in botany, a genus of the Dioecia Pentandria class and order. Natural order of Holoraceae. Amaranthi, Jussieu. Essential character: calyx two leaved; corolla five-petalled: male, nectary seven: female, stigmas two, sessile; capsule with tomentose seeds. There is only one species, viz. I. celosia, a perennial weak plant requiring support, rising twelve feet in height, having large knots at each joint, with oval lanceolate smooth leaves; stems very diffused, branching out on every side; flowers terminating in slender loose panicles, covered with a silky down, of a pale yellow colour. Native of Jamaica, and other islands in the West Indies. IRIDIUM Mr. Tennant, on examining the black powder left after dissolving platina, which, from its appearance, had been supposed to consist chiefly of plumbago, found it contained two distinct metals, never before noticed, which he has named iridium and osmium. The former of these

was observed soon after by Descostils, and by Vauquelin. To analyse the black powder, Mr. Tennant put it into a silver crucible, with a large proportion of pure dry soda, and kept it in a red heat for some time. The alkali being then dissolved in water, it had acquired a deep orange or brownish yellow colour, but much of the powder remained undissolved. This digested in muriatic acid gave a dark blue solution, which afterwards became of a dusky olive green, and finally, by continuing the heat, of a deep red. The residuum being treated as before with alkali, and so on alternately, the whole appeared capable of solution. As some silex continued to be taken up by the alkali, till the whole of the metal was dissolved, it seems to have been chemically combined with it. The alkaline solution contains oxide of osmium, with a small proportion of iridium, which separates spontaneously in darkcoloured thin flakes, by keeping it some weeks. The acid solution contains likewise both the metals, but chiefly iridium. By slow evaporation it affords an imperfectly crystallized mass; which being dried on blotting-paper, and dissolved in water, gives by evaporation distinct octaedral crystals. These crystals, dissolved in water, produce a deep red solution, inclining to orange. Infusion of galls occasions no precipitate, but instantly renders the solution almost colourless. Muriate of tin, carbonate of soda, and prussiate of potash, produce nearly the same effect. Anmonia precipitates the oxide, but, possibly from being in excess, retains a part in solution, acquiring a purple colour. The fixed alkalies precipitate the greater part of the oxide, but retain a part in solution, this becoming yellow. All the metals that Mr. Tennant tried, except gold and platina, produced a dark or black precipitate from the muriatic solution, and left it colourless. The iridium may be obtained pure, by exposing the octaedral crystals to heat, which expels the oyzgen and muriatic acid. It was white, and could not be melted by any heat Mr. Tennant could employ. It did not combine with sulphur, or with arsenic. Lead unites with it easily, but is separated by cupellation, leaving the iridium on the cupel as a coarse black powder. Copper forms with it a very malleable alloy, which, after cupellation, with the addition of lead, leaves a small proportion of the iridium, but much less than in the preceding instance. Silver forms with it a perfectly malleable com

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IRO

pound, the surface of which is tarnished merely by cupellation : yet the iridium appears to be diffused through it in fine powder only. Gold remains malleable, and little altered in colour, though alloyed with a considerable proportion ; nor is it separable either by cupellation or quartation. If the gold or silver be dissolved, the ridium is left as a black powder. The French chemists observed, that this new metal gave a red colour to the triple salt of platina and sal ammoniac, was not altered by muriate of tin, and was precipitated of a dark brown by caustic alkali. Vauquelin added, that it was precipitated by galls, and by prussiate of potash : but Mr. Tennant ascribes this to some impurity. Mr. Tennant gave it the name of iridium, from the striking variety of colours it affords while dissolving in muriatic acid. Dr. Woliaston has observed, that annong

the grains of crude platina, there are some

scarcely distinguishable from the rest but by their insolubility in nitro-muriatic acid. They are harder, however, when tried by the file ; not in the least malleable ; and of the specific gravity of 1.1.5. These appeared to him to be an ore, consisting entirely of the two new metals. IRIS, in anatomy, the anterior coloured part of the uvea of the eye, so called because of its variety of colours, iris being the Latin word for rainbow. The iris is a circular variously coloured part, which surrounds the pupil; it is in some persons blue, in others black, brown, grey, &c. each of which has its peculiar beauty, and is suited to the complexion of the person who has it. See ANATO MY, OPT1cs. In is, in botany, a genus of the Triandria Monogynia class and order. Natural order of Ensatae. Irides, Jussieu. Essential character: corolla six-petalled, unequal, petals alternate, jointed and spreading, stigmas petal-form, cowled, two-liped. There are fifty species. The iris is an inhabitant of every quarter of the world; America, however, produces very few. Several are found natives of the colder regions of Asia, more still of Europe, and most of the Cape of Good Hope. These plants are herbaceous flowering Perennials, both of the fibrous, tuberous, and bulbous rooted kind, producing thick annual stalks, from three inches to three feet in height, terminated by large hexapetalous flowers, having three of the petals reflexed back and three erect : these are very ornamental plants, appearing in flower in May, June, and July.

IRON is a metal of a bluish white co

lour, of considerable hardness and elasti

IRO

city; very malleable, exceedingly tenacious and ductile, and of a moderate specific gravity among metallic substances. It is much disposed to rust by the access of air, or the action of water, in the common temperature of the atmosphere.— The appearance of prismatic colours on its o: surface takes place long before ignition; and at so low a temperature, that the slightest coating of grease is sufficient to prevent their appearance, by defending it from the contact of air: It may be ignited, or at least rendered sufficiently hot to set fire to brimstone, by a quick succession of blows with a hammer. When struck with a flint, or

other hard stone, it emits decrepitating

ignited particles, such as can be obtained from no other metal by the same means. These particles are seldom larger than the two hundreth part of an inch in diameter; and, when examined by a magnifier, are found to be hollow, brittle, and of a greyish colour, resembling the scales of burned iron. This metal is easily oxided by fire. A piece of iron wire, immersed in a jar of oxygen gas, being ignited at one end, will be entirely consumed by the successive combustion of its parts. It requires a very intense heat to fuse it; on which account, it can only be brought into the shape of tools and utensils by hammering. This high degree of infusibility would deprive it of the most valuable property of metals, namely, the uniting of smaller masses into one, if it did not possess another singular and advantageous property, which is found in no other metal, except platina; namely, that of welding. In a white heat, iron appears as if covered with a kind of varnish; and in this state, if two pieces be applied together, they will adhere, and may be perfectly united by forging. Iron is thought to be the only substance in nature, which has the property of becoming magnetical. It is highly probable, from the great abundance of this metal, that all substances which exhibit magnetism do contain iron; but it must be confessed, that there remain many experiments to be made among the earths and powders which exhibit magnetical properties, before this negative proposition, which confines magnetism to iron, can be admitted as proved. When iron is exposed to the action of pure water, it acquires weight by gradual oxydation, and hydrogen gas escapes: this is a very slow operation. But if the steam water be made to pass through a red hot gun-barrel, or through an ignited copper or glass tube, containing iron wire, the iron becomes converted into an oxide, while hydrogen gas passes out at the other end of the barrel. The action of air, assisted by heat, converts iron into a black oxide, containing twenty-five of oxygen. By the action of stronger heat this becomes a reddish brown oxide, containing forty-eight of oxygen. The yellow rust, formed when iron is long exposed to damp air, is not a simple oxide, as it contains a portion of carbonic acid. According to M. Chenevix, there are four stages of oxydation of iron: the first, or mononon, white; the second, green; the third, black; the fourth, or maximum, red. Thenard almits only three, the white, green, and red. The concentrated sulphuric acid scarcely acts on iron, unless it is boiling. If the sulphuric acid be diluted with two or three parts of water, it dissolves iron readily, without the assistance of any other heat than what is produced by the act of combination. During this solution, hydrogen gas escapes in large quantities. Sulphate of iron is not made in the direct way, because it can be obtained at less charge from the decomposition of martial pyrites. It exists in two states, one containing oxide of iron, with .2s of oxygen, which is of a pale green, not altered by gallic acid, and giving a white precipitate with prussiate of potash. The other, in which the iron is combined with .48 of oxygen, is red, not crystallizable, and gives a black precipitate with gallic acid, and a blue with prussiate of potash. In the common sulphate these two are mixed in various proportions. Distillation separates the acid from sulphate of iron, and leaves the brown oxide of iron, called colcothar. Vegetable astringent matters, such as nut galls, the husks of nuts, logwood tea, &c. which contain the gallic acid, precipitate a fine black fecula from sulphate of iron, which remain suspended for a considerable time in the fluid, by the addition of gum arabic. This fluid is well known by the name of ink. See INk. The beautiful pigment well known in the arts by the name of Prussian blue, is likewise a precipitate afforded by sulphate of iron. If two parts of alum, and one of sulphate of iron, be dissolved in eight or ten parts of boiling water, and a solution of prussiate of potash be added as long as any effervescence and precipitation are produced, the precipitate, thoroughly washed by effusion of boiling water, will have a green colour. . This is owing to the yellow oxide of iron thrown down

with the prussiate, which must be dissolved by adding muriatic acid. The deep blue powder, insoluble in this acid, is then to be washed and dried for use. According to Professor Proust, the iron in Prussian blue contains 48 of oxygen, and is obtained only from a super-oxygenated sulphate; the precipitate from a pure alkaline prussiate and sulphate of iron with a minimum of oxygen being white, and containing only .27 of oxygen. This may explain a fact, observed by a French colourman, who, having mixed some Prussian blue and white lead with nut oil, and set it by for some time covered with water, found the surface only blue, and all the rest white. On pouring it out on his stone, and beginning to grind it afresh, with intention to add more Prussian blue, he found the colour gradually .."; of itself. Here it might be supposed that the oxide of the prussiate had parted with oxygen to the oil, or the oxide of lead, or both, thus becoming white, except that on the surface, which was supplied with oxygen from the superincumbent water; and that it recovered its colour by attracting oxygen from the air. . But on this supposition it would seem, that light must contain oxygen, since the colour of this paint, spread on wood or paper, returned by exposure to light in vacuo, as well as in the open air. The colour of Prussian blue is affected by the contact of iron. Mr. Gill, finding a knife with which he was mixing some Chinese blue acquire a green tinge, spread a little of it, and afterwards a httle Prussian blue, sufficiently diluted, on the blade of a knife, and with a camel hair pencil took off enough to form a tint on paper, and thus continued till he had taken off, in the first instance, thirty-six, and in the second eighty-six, without adding any fresh colour. These tints differed in regular gradation from greenish blue to green, olive-green, yellowish green, yellow, and so on to a buff. Concentrated nitric acid acts very strongly upon iron filings, much nitrous gas being disengaged at the same time. The solution is of a reddish brown, and deposits the oxide of iron after a certain time, more especially if the vessel be left exposed to the air. A diluted nitric acid affords a more permanent solution of iron, of a greenish colour, or sometimes of a yellow colour. Neither of the solutions afford crystals; but both deposit the oxide of iron by boiling, at the same time that the fluid assumes a gelatinous appearance. Diluted muriatic acid rapidly dissolves

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