jetar but as its alloys have not been much exained, we fhall confine ourfelves to thofe which we been propofed for ufe. (1116.) Bergman found that manganese combid readily with copper, forming a very malleable loy, of a red colour, which fometimes becomes een by age. Gmelin fucceeded in forming this by by fufing the black oxide of manganefe along th copper, and he propofed to fubftitute this in ice of the alloy of copper and arfenic, which is uch employed in the arts, but is very dangerous utenfils which are intended to hold putable li ids.-Minganefe combines with iron, and makes white and brittle.-It alfo combines with tin, ticarcely with zinc. 2117.) It appears that only the white and red ides of manganefe, are capable of combining th the acids, and that the black oxide does not abine until after it has given out its excefs of ygen. For all we know of the falts of mangawe are indebted to the illuftrious Bergman and seele, who alfo first made us acquainted with oxide which has proved of fuch importance as hemical agent, and of fuch extenfive use in arts I manufactures. The affinities of oxide of manhefe for the acids are, according to Bergman, in following order. OXIDE OF MANGANESE. I. SULPHATE OF MANGANESE. 2118.) This falt exifts in two states, the Sulphate, 120.) As the marks which it is neceffary to put cloth are apt to be effaced by bleaching in Oxymuriatic acid, Hauffman propotes a folu tion of fulphate of manganefe, mixed with fugar, gum, or any vegetable fubftance, fo as to bring it to the proper confiftency, by which lines or names may be written on the cloth. When expofed to the oxymuriatic acid thefe figures acquire a permanently yellowish brown colour." II. NITRATE OF MANGANESE. (2121.) Nitric acid diffolves in manganefe with effervefcence and extraction of nitrous gas; it dif folves the white oxide without effervefcence; by long digeftion on the black oxide a little of it is diffolved, but the folution goes on rapidly if a little fugar is added, See, (2110.) The Nitrous acid is converted into nitric acid, when it acts upon the black oxide and the oxide is converted into the white oxide which combines with the acid. In all thefe cafes only the white oxide combines with acid. The folution is colourlefs, and does not cryftallife; heat expels the acid leaving the white oxide, which is also precipitated by alkalies. III. MURIATE OF MANGANESE. (2122.) The muriatic acid diffolves manganese with emiffion of hydrogen gas, it diffolves white oxide without effervefcence: when heated upon the black oxide, oxy-muriatic gas efcapes with effervefcence. See (778.) The acid divides into two portions one part of which absorbs oxygen from the oxide and flies off in a ftate of gas, the other por tion combines with the white oxide thus formed. If fugar or any vegetable substance be present, carbonic acid gas is emitted, and muriate of manganefe formed, See (2110.) The folution of this falt is colourlefs and cryftallizes with dif ficulty. (2123.) We do not esteem it neceffary to enter farther, into the falts of manganefe, not that we esteem them useless but that they have not yet been converted to any ufe. SECT. XXI. CHROMIUM. (2124.) A beautiful red mineral with a shade of yellow, generally cryftallized in four fided prifms, occurs in the mine Berefof in Siberia, this mineral was used as a paint and is become exceedingly fearce and dear. Pallas fuppofed it a compound of various metals. Various opinions were advanced concerning its compofition. Vauquelin in 1797 found it to be a combination of oxide of lead and a peculiar acid whofe bafis was metallic. By expofing this acid to a violent heat when mixed with charcoal powder, he obtained from it a new metal to which he gave the name of Chromium, from its property of communicating colour to other bodies. His conclufions were verified by Klaproth and other chemists. This metal is of a white colour with a fhade of yellow; it is very brittle, and only melts by exceffive heat; it combines with three dozes of oxygen, forming the green and brown oxides, and the yellow when it affumes all the properties of an acid. The metal diffolves with difficulty in the acids. The nitrate of chromium yields by eva poration octahedral cryftals of a fine violet colour, but as the ore of this metal is very scarce and dear, few of its properties or combinations have been examined. SECT (2125.) THE word molybdenumis derived from the term by which the Greeks denoted the mineral which the Latins called plumbago, and we in, dicate by the name of black-lead. The metallic ore now under confideration very much resembles plumbago, and was long confounded with it, until Scheele afcertained the difference, and to this ore he affigned the name of molybdena. (2126.) Only one ore of molybdenum has yet been found, namely the fulphuret, and it occurs in va rious parts of the world, particularly in Invernefs, fhire. It occurs in various parts of the land of Lewis, and particularly near the mouth of Loch Roag, in irregular veins, or detached maffes in garnet rocks. It has always a leaden colour, ftains the fingers, and marks bluish black. It is fometimes cryftallized in hexahedral prifms and tables, often maflive, and fometimes mouldered into fand, or black mud. (2127.) Scheele in 1778 obtained fulphur from this ore, and a whitish powder, which poffeffed the properties of an acid. Hielm in 1782, by a laborious course of experiments first fucceeded in reducing this powder to the metallic itate; and his conclufions have been confirmed by chemifts of the firft eminence. (2128.) To reduce molybdenum, the ore is flowly and repeatedly roafted in a moderate red heat, until it falls into fine powder, and paffes through a fieve. The powder is diffolved in ammonia, the folution filtered, and evaporated to drynefs, The refiduum being moderately heated with a little nitric acid, leaves a white powder, which is oxide of molybdenum. This oxide being mixed with oil, or charcoal powder, and expofed to a moft violent heat, is reduced to the metallic ftate. This metal has only been obtained in mall agglutinated metallic grains, which the most violent heat that can be applied has yet proved infufficient to fufe into a mafs, and hence its properties are very little known, (2129.) It is of a yellowish white colour, internally greenish white. Its fpecific gravity 7400. When heated in an open veffel, it attracts oxygen and is converted into white oxide, which fublimes in fmall needle fhaped cryftals. Mr Hatchet afcertained that it is capable of forming four oxides, 1. The black; 2. The blue; 3. The green, to which he gave the name of molybdous acid; 4. The yellow, or white, which is the molybdic acid. (fee 874 &c.) (2130.) This metal readily combines with fulphur, and the compound every way refembics the mineral fulphuret of molybdenum. It combines alfo with phofphorus. Hielm with indefatigable induftry,afcertained the effect of combining molybdenum in various proportions with other metals. He found iron to be the metal with which it united moft readily, and with which its alloy is moft likely to prove ufeful could molybdenum. be obtained in fufficient quantity. (1130.) The oxides of molybdenum combine with feveral of the acids; but as two of its oxides tion we have upon this fubject is from (2132.) A mineral is found in the George W fort mine in Saxony, to which the German ralogifs in their ufual rage for unmeaning had affigned the name pech blend, blind Klaproth in 1789 afcertained that this confifts chiefly of fulphur combined with ap ar metal, to which he gave the name of rat from the name which the German attronenes affigned to the Georgium fidus, the new pa difcovered by Herfchel. His difcoveries ve terwards confirmed by Richter and Bucho. ores of this metal have been found fince, in primitive mountains, in Bohemia, N Cornwall, and France. They are genera black colour, and fometimes of a green, tain, befides fulphur, a mixture of other and fubftances. (2133.) As no procefs has yet been inverte obtaining this metal in large quantity, we unnecellary to detail the means which have adopted to reduce it to its metallic ftate. Ma it certain whether it ever has been obtained pure ftate. Its luftre is confiderable; its iron grey; it yields to the file; its specific p according to Klaproth; is 8100, but Buck tained it as high as 9'ooo. This is a decifive that its purity is yet uncertain. (2134) When heated to redness in an ope fel, it is foon changed into a grey powder which is its protoxide. This o fifts of 95'1 uranium, 4'9 oxygen. Dark grey inclining to violet, Greenith brown, Greyith green, Orange, Lemon yellow. (2136.) As this metal has never been ofties" quantity, nothing is known refpecting the a forms with other metals. (2137-) The oxides of uranium comhite *** are themfelves acids, it feems very probable that acids; and all we know refpecting its fi thefe oxides undergo changes during the act of rived from Klaproth, Richter, and Buchol. their combination with acids. The only informa diftinguishing property of these falts is that they fre moftly foluble in water, and that their folution has a yellow colour. A few of them may be mentioned. I. SULPHATE OF URANIUM. (2138) This falt is eafieft formed by boiling diJuted fulphuric acid upon the peroxide of uranim. By extremely flow evaporation, the folution fields cryftals of a beautiful yellow colour. Actording to Bucholz, this falt confifts of 18 acid 70 oxide 12 water 100 II. NITRATE OF URANIUM. (1139.) The nitric acid diffolves uranium with miffion of nitrous gas. But this acid more readi y diffolves the oxide, without emillion of gas. The folution has a yellow colour, and as this falt is extremely foluble in water, the beft way to tryftallize it is to expofe it to very long and flow evaporation by a very moderate heat. When the acid is faturated with oxide the cryftals are lemon yellow, tinged with green at the edges. When there is a flight excefs of acid they have all a greenish colour. They are in the form of tables, often hexagonal; fometims they are ob tained in large four-fided rectangular flat prifms. Thefe cryftals are reckoned the most beautiful of all the metallic fatts. They are ftill more foluble in alcohol than in water, and this folution, by flow vaporation. yields regular cryftals. Thefe cryf tals deliquefce in damp air, and fall to powder where the air is heated to about reo By greater heat the acid is expelled, and the falt decompofed. According to Be holz this falt contains o. oxide 25 acid 14 water 100 III. MURIATE OF URANIUM. (2140) The muriatic acid fcarcely acts upon Dranium, but it diffolves its oxide, and forms a falt which cryftallizes in four fided tables, and is deliquefcent. (2141) The other falts of Uranium do not feet to require particular notice. But as the oxide of uranium feems capable of being procured in great. er quantity from its ores. than the metal itself, it may poffibly be ufefully employed to colour glafs, or to paint porcelain or enamels; or being mixed with other oxides, to convey various fhades of colour to thefe elegant products of art and fcience. SFCT. XXIV. TUNGSTEN (1142) A mineral is found in Sweden, of a white colour, which had obtained the name of tug flen, ponderous fone, on account of its great weight. In 1781, Scheele afcertained that it was compofed of time, and an earth-like fubftance having acid properties, to which he therefore gave the name of rungftic acid. Bergman conjectured this acid to have a metallic basis; and D'Elhuyart VOL. V. PART II. haying obtained the fame acid from a mineral known in Germany by the name of wolfram, fuc ceeded in reducing it to the metallic state, to which he gave the name of tungsten. (2143.) The ores of tungsten bave only been found in the primary mountains, and they gene rally accompany ores of tin. They occur in Germany, Sweden, Co nwall, France, and Spain. Only two forts of them have been difcovered, Ox4 ides, and Tungftate of lime. The oxides have ob tained the name of wolfram, and always accom pany ores of tín. They are either maffive or cryf tallized, of a dark greyish or brownish black colour. The tungftate of lime is commonly maffive, but fometimes cryftallized. Its colour varies from yellowish or greyifh white to fnow white. These ores contain the oxides of iron and of manganese, and fome other fubftances, as well as the oxide or acid of tungsten. (2144.) To reduce the ore the tungstic acid is mixed with charcoal powder, and exposed to the moft violent poffible heat in a covered crucible The metal forms a congeries of fmall globules, fome of which are as large as a pin-head. But to reduce this metal to complete fufion, a heat generated by a ftream of oxygenous gas feems neceffary. (2145.) Tungften, thus obtained, has much brilliancy, with the colour of iron. Its specific gravity is 17'6, and it is next to gold and platinum in denfity. It is very brittle, though among the hardeft of the metals. It seems to cryftallize on cooling. (2146.) Heated in an open veffel it attracts oxygen, and is converted into an oxide. It is capable of forming two oxides, the black, and the yellow. -The yellow, or peroxide, also known by the name of tunglic acid, (fee 872) occurs native in the mineral called wolfram, and may be obtained by boil ing three parts of muriatic acid on one of the mineral, the acid to be decanted in about half an hour, when it gradually depofits a yellow powder. This powder is to be diffolved in ammonia, the folution evaporated to drynefs, and the mafs expofett fome time to a red heat. The yellow powder which remains is the oxide in a pure ftate. Tho' not foluble in water, it remains long fufpended in, it, fo as to form a fort of yellow milk. It has no acid properties (872) and is compofed of 80 tungsten 20 oxygen 100 The black oxide may be obtained by beating the yellow oxide fome hours in a covered crucible, which expels part of its oxygen. (2147.) Tungften combines with fulphur and phofphorus. The Elhuyarts tried to combine tungften with various metals; but unless this metal could be reduced in greater quantity, and more completely fufed, no practical advantage is likely to refult from its alloys. The difficulty of redu cing tungften, and of obtaining it in quantity, have alfo prevented its falts from being examined, and they remain wholly unknown. But as the oxid might easily be procured, it might be worth while to try its effect in colouring glafs, and in enamel painting. (2149) In 1781 Mr Gregor difcovered a black fand in the valley of Menachan, in Cornwall, refembling gun-powder, which he found to be compofed almoft entirely of iron and the oxide of a new metal, to which he gave the name of mena chine, from the place where he found it. In 1795 Klaproth analyfed a brownish red mineral, which mineralogifts called red hore, and found it entire ly compofed of the oxide of a new metal to which he gave the name of titanium. In 1797 he examined the black mineral difcovered by Mr Gregor, and found it to be a compound of the oxides of iron and his titanium. But the name affixed by Klaproth has been retained, from his great cele brity. Neither of thefe chemifts were able to reduce this oxide. (2150) The ores of Titanium have been found in various countries, chiefly in the primary moun tains, or in alluvial earth. They are all reducible to one, namely the oxide, which mineralogifts have laboured to perplex and confufe, in their ufual manner, by affigning to them a variety of caprici. ous names. Lampadius is faid to have reduced the oxide, by mixing it with charcoal, and expofing it to a very violent heat. That the colour of the metal is that of copper, but deeper. That it oxidizes when heated, and affumes a blue or purple colour, and detonates when thrown into a red hot nitre. Another oxide is of a red colour, occurs native, and is the oxide on which Klaproth operated. Its higheft oxide is white, and may be formed by fufing the red oxide in four times its weight of potash, and diffolving the whole in water. A white powder feparates, which is the white oxide of titanium. It confifts of 11 parts oxygen, combined with 89 parts of red oxide. (2151.) Titanium does not combine with fulphur. but Mr Chenevix fucceeded in combining with phofphorus It does not combine with other metals, as far as is yet known. The acids feem to act chiefly on the carbonate of titanium, which is formed by melting one part of red oxide, and fix of carbonate of potash in a crucible, wafhing, the mafs with water, which leaves a white powder. This is the carbonate of titanium, and confifts of 75 white oxide 25 carbonic acid 100 it ftreaks." By a very ingenious analysis, Mr H chett afcertained that this mineral confilec of part of oxide of iron, and rather more than thre parts of a white fubftance which proved to be acid with a metallic bafis.-For the properti this acid we refer to (890, 891, &c. &c.) proved that this acid differed from all the c metallic acids, and of courfe inferred that its must be a peculiar metal, to which he gav name of columbium, in honour of the original coverer of the western continent. All attor however, to reduce this acid to the metalic tr failed though it was reduced to the oxide f and as the quantity of the mineral he had to rate upon was fmall, and no more of it b reached Europe, we deem it unneceffary to into a detail of Mr Hatchett's very ingenious riments concerning it, or into the combinatio its oxides with acids. (2153) Two minerals have been long know the parish of Kimito in Finland. The one bluish or blackish grey colour, metallic lore, compact fracture, great hardnefs, and fpecie vity 7953. The other occurs in fmall kidney: maffes of a deep grey colour, metallic lar, hardnefs and granular fracture. Its specific ty is 5'130. From both thefe minerals Mr berg, an eminent Swedish chemift, bas later tracted a white, powder, which he afcertin be the oxide of a peculiar metal; to which, caufe the oxide refufed to combine with acic has affigned the name of tantalium, alluding to fable of Tantalus' cup. He was not able to duce this oxide into the metallic ftate. B combines with the two fixed alkalies, for compounds foluble in water. When fled phofphate of foda, and borax, it forms co glaffes. SECT. XXVIII. CERIUM. (2154.) In 1750 a mineral was difcovered i copper mine of Baftnas, in Weftmann land is den, which, from its weight, was fome time founded with tungen. Various examination been made of this mineral at different times minent chemifts, who adopted contradictory nions concerning it. At laft Hifinger and lius, two Swedish chemifts, fubjected it to a rigid examination, and difcovered in it ap fubftance which they affirmed to be a meta ide.. To this difguifed metal they gave their of Cerium, from the name Ceres which Phat chofen to affix to the new planet lately by him. All attempts to reduce this ex metallic ftate, have hitherto proved abortive. The oxides of this metal have not been tried in oxide is firft of a white colour, but after colouring glafs, or enamel painting. SECT. XXVI. COLUMBIUM. (2152.) This metal was discovered by Mr Hatchett-in 1802 in a mineral belonging to the British Mufeum, which had been fent to Sir Hans Sloane, among various specimens of iron ores from Mafiachufetts, and which he had defcribed in his catalogue as "A very heavy black ftone with golden heated to rednefs, it becomes cinnamon b But it is capable of various degrees of oxidis and its different degrees are marked white, yellow, red, and dark brown. T changes are owing to combination with 65% feems manifeft, because when muriatic gefted upon its oxides, a part of it fits of Itate of oxymuriatic acid gas. Vanquinta ced thefe various degrees of oxidizement to The protoxide of a white colour, and the peroxide of a reddifh. (2155.) The oxides of cerium combine with all the acids, forming falts of cerium. The general properties of thefe falts are, 1 1. That their colour is either white, or yellow, ac cording to the extent to which their bañis is oxidized. 2. Their folutions have a fweet taste. 3. Hydrofulphurét of potash precipitates the white oxide of cerium. Sulphureted hydrogen ccafions no precipitaté. 4. Pruffiate of potash caufes a milky precipi ate, which is foluble in nitric and muriatic acids. 5. Oxalate of ammonia produces a white preciitate, which is infoluble in nitric and muriatic acids 6. No precipitate is occafioned by gallic acid, r infufion of nutgalls. (2156.) As the mineral from which oxide of ceium is extracted has only yet been found in one nine, we deem it unneceffary to enter into a minute lefcription of its faits.-Perhaps this oxide, were it ound in fufficient abundance, might be advantaeously employed in colouring glass, and in enanel painting. (2157) In the preceding parts of this work, we ave dwelt chiefly upon thofe fubjects which were nown to be of practical utility, or which we hought might be rendered ufeful in practice. In he many things we have omitted, we would not with it fhould be understood that we meant to ininuate that they were of no ufe; but that their fe was not at prefent afcertained. In a treatife if this fort, which profefles to exhibit a fummary f the prefent state of chemistry, a fubject fo vaft, nd on which facts and difcoveries are accumulaing more rapidly than it is poffible to arrange and ethodize them, we are obliged to confine ourelves to thofe facts which may ferve to illuftrate he principles of the fcience, or which may appear apable of being carried into practical effect. SOAPS. (2158.) We referved the confideration of thefe ompounds until all the fubftances were difcuffed which enter into their compofition. Soaps are ormed by the union of a fixed oil with a bafis. The bafe which combine with oils, are either alalies, acids, earths, or metallic oxides. The aps are diftinguished from each other by their afes. Thus we have alkaline, acid, earthy, and metallic foaps. We learn from Pliny that foaps vere firft invented by the ancient Gauls, or Gernans. Olive oil is efteemed the best for the fabriation of foaps; but tallow, butter, fish oil and a reat variety of oils are employed with advantage. Chaptal, in place of oils, propofed to combine old wool, and fhreds of woollen cloth with the alcaline ley, and this practife has been profecuted a France with confiderable fuccefs. I. ALKALINE SOAPS. 1. SODA OR HARD SOAP. (2159.) The diftinguishing property of foap hich has foda for its bafis, is that it is commonly a folid form, whereas that which is formed by Potah is always in a foft or gelatinous state. 1 (2160.) To prepare this foap, the foda of com. merce, or kelp, are first rendered caffic, o have their carbonic acid abstracted from them, by being mixed in powder with lime newly flacked and fifted. (See 1285). This mixture is made in a large wooden vat, and the lime is commonly in the proportion of a fifth of the weight of the toda. But the quantity of lime neceffary depends much upon its own purity, compared with the purity of the alkali on which it is to operate. The veffel is now filled with water, fo as to cover the mixture to a confiderable depth. The lime abftracts the carbonic acid from the foda, and the water becomes charged with pure alkali. After this water has re mained feveral hours, it is drawn off by a stop-cock, and is called the firft leg. A fecond and third quantity of water is added, and after remaining a fufficient time on the mixture, they are drawn off, and are called the fecond and third levs. To make certain that all the foda is diffolved and drawn off, a fourth quantity of water is poured in, and is referved for making the firit ley of a future operation. (2161.) A quantity of oil, or tallow, equal to about fix times the weight of the foda employed, is now put into a boiler, with a quantity of the third or weakest ley. The mafs being brought to boil, is perpetually stirred with a long wooden lever. The whole of the third and fecond leys are added at intervals. The oil combines with the alkali and becomes milky. When it acquires a certain confiftence, a little of the firft or ftrongeft ley is added, and the whole is conftantly ftirred. As the fo.p forms, it begins to feparate from the watery part of the liquid, which is much facilitated by adding a portion of common fait. The boiling and agitation are still continued for about two hours, when the fire is withdrawn, and the whole allowed to remain at rest. After fome hours, the foap feparates completely from the liquid part, and fwims on the furface. The liquid is now drawn off, and as it contains carbonate of foda it fhould be referved for future ufe. A little weak ley is now added, and the mafs is brought to boil again, with conftant ftirring. During this operation the remainder of the firft ley is added at intervals. A little of the foap is taken out from time to time, and allowed to cool, by which it is judged when the foap arrives at the proper confiflency. When this happens the fire is withdrawn, and the watery part drawn off as before. It is now heated again with a little water, and brought to the confitence of a foft pafte; when it is poured into wooden boxes, or moulds, where it confolidates. Thofe boxes have a little powdered chalk upon their bottoms, to prevent the foap from adhering. They come afunder in pieces, and the fuap is cut into bars either by a ftring or wire drawn acrofs it.-Soap made with foda and tallow is of a white colour, and is ufually called white foap. But they often ufe a mixture of rofin among the tallow, which gives it a yellow colour, and this forms the common yellow foap of this country. (2162.) Soap is foluble both in water and in al cohol. Manufacturers often keep it in falt water, which increafes its weight without diffolving the foap. The different proportions of water contained in foap have occafioned much diverfity in its * Sssz analyfi, |