quor is to be kept, and when diluted with cold water, is to be drank in the summer-time, in order to remove thirft.

OXYGLYCUS CERASUS, a name given by the editor of Dalzel's hiftory of DAHOмY, to a very extraordinary fruit, produced in that country and other parts of Africa. It resembles a small olive in every respect but colour; being of a dufky reddifh hue, changing at the end next the talk to a faint yellow. The pulp is firm, and almost infipid; the ftone is hard like that of the olive. Af. ter having chewed one or more of these berries, and swallowed or fpit out the pulp, a glafs of vinegar taftes like fweet wine; a lime feems to have the flavour of a ripe China orange; and a fimilar change is produced on other acids; the ordinary effects of which upon the palate are deftroyed in a mot unaccountable manner without effervef cence, or any perceptible motion. The effect, indeed, is very different from neutralization by the mixture of an acid and alkali; fuch combination producing a neutral salt, while this miraculous berry feems to metamorphofe acids into fweets. Food, or drink, not containing any acid, fuffers no change, by the previous ufe of this fruit: Its effect upon acids continues, even after a meal, though in a smaller degree. The natives ufe it to render palatable a kind of gruel called guddoe, which is made of bread after it becomes too ftale. They defcribe it as the fruit of a large tree. Mr Dalzel raised plants 6 or 7 inches high from this fruit, and tried to carry them from Angola, to the Botanic garden at St Vincent's; but they perished in the paffage. He preferved the berries in fpirits, in fyrup, and in a dry form: but they loft their wonderful property in all these preparations. The plant is an evergreen, and the leaves refemble those of the olive.

OXYLUS, one of the generals of the Heraclidæ, when they recovered the Peloponnefus. He became king of Elis. Pauf. v. c. 4.

(1.) * OXYMEL. n. ƒ. ložukeλi, ožus and M.] A mixture of vinegar and honey.-In fevers, the aliments prescribed by Hippocrates, were ptifans and decoctions of fome vegetables, with oxymel or the mixture of honey and vinegar. Arbuthnot.

(2.) OXYMEL. See PHARMACY, Index. (1.)* OXYMORON.n. S.[ožvμwgov.] A rhetorical Agure, in which an epithet of a quite contrary fig. nification is added to any word.

(2.) OXYMORON. See ORATORY, § 229. OXY-MURIAT. . . a falt formed by the combination of the Oxy-Muriatic Acid, with different bafes. "Though the oxy-mutiatic acid was difcovered" (fays Dr Thomfon) by Scheel, it was not till 1986, that Berthollet difcovered the poffibility of combining it with different bafes, and forming that clafs of falts now named Oxymuriats. Thefe falts cannot be formed by diffolving the different bafes in the acid, while liquid, in confequence, perhaps, of the ftrong affinity it has for water; but may be eafily formed by the following process: Diffolve the bafe which is to be combined with the acid, or its carbonate, in water, or mix it with water if it be infoluble, and, putting it into one of Woulfe's bottles," (See CHEMISTRY, Index,)" caufe oxymuriatic acid, in the ftate of gas, diftilled in the ufual man

ner, to pafs through it. The acid combines with the base, and (if a carbonate be used) an effervescence takes place, owing to the difengage ment of the carbonic acid gas. As the bafe be comes faturated with acid, the oxy-muriat gradually precipitates in the ftate of crystals. At the fame time with the oxy-muriat a quantity of common muriat is formed; but it may be easily separated, by diffolving the falt in a fmall quantity of boiling water, and allowing it to cool; the greater part of the oxy-muriats fall down in crystals, whereas the other falt remains in folution.""The oxy-muriats may be distinguished by the following properties: 1. When heated moderately they give out a great quantity of oxygen gas, and are converted into common muriats. z. When mixed with combustibles, they detonate with much greater violence than the nitrates. This detonation is occafioned, not only by heat, but by friction and percuffion, and often takes place fpontaneoufly. 3. Soluble in water, and capable of cryftallizing when the folution cools.-The greater number of them have been but flightly examined; owing probably to the difficulty of forming them rapidly. Some of them, however, have been introduced into the procefs of bleaching with much advantage. And thofe of them which are already known have given rife to fome of the most brilliant and aftonishing experiments exhibited in chemistry." Syft. of Chem. vol. II. p. 336-338. Dr Thomfon enumerates four fpecies of oxy-mu. riats, already known; befides the

I. "OXY-MURIAT of BARYTES," which (he fays)" is ftill unknown. Fourcroy has afcertained, that when oxy-muriatic acid gas is received, containing water and carbonate of barytes, the ba rytes is gradually diffolved, and the carbonic acid emitted; oxy-muriat of barytes in that cafe was no doubt formed.

2. "OXY-MURIAT OF LIME may be prepared by the common procefs. Its properties have not been examined, but it has been substituted by Mr Tennant of Glafgow for oxy-muriat of potass, in bleaching, and is faid to answer the purpose completely. The oxy-muriat of potass had fucceed ed with the paper-makers, but the bleachers of linen did not find it to answer. The oxy-muriat of lime is prepared in the ufual manner, by means of chalk, and is used by the bleachers in a liquid form. It is faid, however, to be now prepared for them in confiderable quantities, and fold in a dry state.

3. "OXY-MURIAT OF POTASS. This extraordinary falt, firft formed by Berthollet, has been fince examined by a great number of chemifts, LAVOISIER, Dolfuz, Van Mons, Fourcroy, Vauquelin, Hoyle, &c. have investigated its properties, and difcovered many of the fingular effects it produces." Dr Thomfon adds in a note, that "it was in fact firft difcovered by Dr Higgens, who defcribed the method of forming it, and fome of its properties fome time before Berthollet, under the name of faltpetre.""It is prepared by dif folving one part of carbonate of potafs in 6 parts of water; putting the mixture into Woulfe's bottle, and faturating the potafs with oxy-muriatic acid gas. When the faturation is nearly com pleted, the oxy-muriat falls down in cryftals. It

may

may be purified by folution in boiling water. As the water cools, the pure oxy-muriat cryftallizes. The crystals are to be dried between folds of blotting paper. According to Hauy, the primitive form of the crystals is an obtufe rhomboidal prifm. But it is ufually obtained in small thin plates, of a filvery whiteness. It is only by allowing an unfaturated folution of it in boiling water to cool flowly, or by exposing a solution in cold water to fpontaneous evaporation, that it is obtained in large regular rhomboidal cryftals. Its tafte is cooling, auftere, and disagreeable, fomewhat analogous to that of nitre. Its fpecific gravity is 1989. When rubbed fmartly, it phosphorefces, or rather emits a number of sparks of fire. It is foluble in 17 parts of water, at the temperature of 60°, and in 24 parts of boiling water. It is not fenfibly altered by exposure to the air. When heated, it readily undergoes the watery fufion. If the heat be continued, it boils, and gives out about the 3d of its weight of oxygen gas. From this falt oxygen gas can be obtained in the great. eft purity. After the effervefcence is over, there remains common muriat of potafs. According to Fourcroy, it is compofed of 67 parts muriat of potafs, and 33 oxygen. The moft aftonishing properties are thofe which it exhibits, when mixed with combustibles. All combuftible fubftances whatever are capable of decompofing it, and, in general, the decompofition is attended with violent detonations. When 3 parts of this falt and one part of fulphur are triturated in a mortar, the mixture detonates violently: the fame effect is produced when the mixture is placed upon an anvil, and ftruck fmartly with a hammer. Nay, it even fometimes detonates fpontaneously, with out any perceptible friction, and ought not therefore to be kept ready mixed. Charcoal produces the fame effects, though not fo violent. This pro. perty induced Berthollet to'propose it as a fubftitute for gun powder. The attempt was made at Effone in 1788; but no fooner had the workmen begun to triturate the mixture of charcoal, fulphur, and oxy-muriat, than it exploded with violence, and proved fatal to Mr Letors and Mademoiselle Chevraud. The force of this gun-powder, when it is prepared, is much greater than that of the common fort; but the danger of preparing it, and even of ufing it after it is prepared, is fo great that it can hardly ever be fubftituted with advantage for common gun-powder. Phof phorus alfo detonates with this falt, either by trituration or percuffion. The quantities of each ufed ought not to exceed half a grain, or at most a grain, otherwife the experiment may be attended with fome danger. It detonates alfo, when treated in the fame way, with almoft all the metals, and with cinnabar, pyrites, fugar, gums, oils, alcohol, &c. When thrown upon platinum heated to whiteness, it does not detonate; but fublimes. The furface of the platinum, however, is oxidated; for acetous acid diffolves part of it, and when the pruffiat of lime is poured into the folution, the liquid becomes of a greenifh-white coJour. The acids decompofe it, and expel the oxymuriatic acid in a state of such condenfation, that it acts inftantaneously upon all combustibles which come in its way, and occafion aftonishingly rapid VOL. XVI. PART II.

and brilliant combuftions. When fulphuric acid is poured upon it, a detonation takes place, a red flame is emitted, and a ftrong colour of oxy-muriatic acid is exhaled. If fulphuric acid be poured upon a mixture of this falt and fulphur, charcoal or the metals, or oil of turpentine, or almost any combustible, a very brilliant flame is emitted. When this falt is triturated in a mortar with a little cotton cloth, fmall repeated explosions are heard, fimilar to the crack of a whip; and if the cotton be dry and warm, it fometimes takes fire. It always does fo, when, after the trituration has been continued for fome time, fulphuric acid is poured upon the cotton. When nitric acid is poured upon this falt, the oxy-muriatic acid is difengaged, but without any detonation or flame. When this acid is poured upon a mixture of oxy. muriat of potafs and phosphorus, flakes of flame are emitted at intervals for a confiderable time. The theory of these explosions was first pointed out by Berthollet. The oxygen of the oxy-muriatic acid combines with the combuftible, and at the fame time lets go a quantity of caloric; and trituration or percuffion acts merely by bringing the particles which combine within the sphere of each others attraction. This falt was employed in BLEACHING, after the discovery of the whitening property of oxy-muriatic acid: but other compounds have been lately fubftituted in its place."

4."OXY-MURIAT of SODA, has not hitherto been examined. From the experiments of Dolfuz and Godolin, we learn, that it may be formed by the fame procefs as oxy-muriat of potass; that it cryftallizes in prifms; that it detonates on red hot coals, and that it precipitates fulphate of iron brown.

5."OXY-MURIAT OF STRONTIAN was firft formed by Meffrs Davy and Clayfield. The combi nation only fucceeds when oxy-muriatic gas is paffed through a faturated boiling folution of ftrontian in water. When the frontian is faturated, the folution has a dufky orange colour. It yields cryftals with difficulty, in confequence of the great folubility of the oxy-muriat. By great evaporation and cooling, fine needle-form cryftals are obtained. Alcohol diffolves them and burns with a red flame. They detonate flightly with phofphorus and charcoal. When fulphuric acid is poured into the folution of this falt in water, a vivid light is emitted, and a great increase of temperature takes place; but no light appears when the acid is poured upon the dry falt.

(1.) OXY-MURIATIC ACID, an acid compofed of Muriatic Acid and Oxygen. "It may be be procured," (fays Dr Thomfon Syft. Chem. Vol. II. p. 67-75.)" by the following process. Put in. to a glafs matrafs a mixture of 3 parts common falt, and one part of the black oxide of manga. nefe. From this matrafs a bent glafs must pass, either into water previously boiled and ftill warm, or, which is better, into a mercurial trough; and glafs jars, filled with water or mercury, must be inverted over the end of the tube to receive the product. When the apparatus is fully prepared, two parts of concentrated fulphuric acid, (previ ouily diluted with rather more than half its weight of water, elfe the matrafs cracks,) are to be poured Gggg

into

the remaining sth with ammonia, and the tube be then inverted over water, an effervefcence enfues, and azotic gas is extricated. This acid combines with fixed alkalies, earths, and several metallic oxides, and forms with them falts of a very peculiar nature, named Oxy-muriats." (See OXY-MURIAT, N° 1-5.) “As thefe combinations cannot be made directly with liquid oxy-muriatic acid, it has been impoffible to afcertain the affinities of this acid. Oxy-muriatic acid gas reddens nitrous gas and converts it into nitrous acid. It produces no effect upon any of the acids hitherto defcribed, except the SULPHUROUS and PHO's PHOROUS, which it converts into SULPHURIC and PHOSPHORIC." Dr Thomfon mentions fome experiments of Mr Lambe, to procure oxy-muriat of iron; but as thefe experiments, when Trepeated by Meffrs Vauquelin, Guyton-Morveau, and Bouhlon-Lagrange, with every poffible precaution, did not produce a fingle particle of that oxy-muriat, we need not quote them. The Doc tor concludes with remarking, that "Oxy-muri atic acid is one of the most important, and fortu nately one of the eafieft procured, of all the acids. It is employed with great advantage in BLEACHS ING, and in a great variety of chemical procetles." (3.) OXY-MURIATIC ACID, USE OF, IN BLEACH ING. This acid is the principal agent in the new process of bleaching. (See BLEACHING, PART II.) But till very lately, perhaps with many ftill, the bleachers were in the practice of adding fome alkali to the acid, notwithstanding the ftrong objections which M. Berthollet made to that addition, and notwithstanding the proofs urged by Mr Rupp, that it increases the expense of bleaching about 40 per cent. The chief reason for perlifting in a practice to which fuch objections were urged was, that the addition of the alkali deprives the liquor of its fuffocating effects, without deftroying its bleaching powers. Mr Rupp, however, has contrived the following apparatus, in which may be fafely used the pure oxy-muriatic acid fimply diffolved in water, which is at once its cheapest and beft vehicle. Fig. 1. Plate CCLXV. is a fection of the apparatus. It confifts of an oblong deal ciftern ABCD, made water-tight, A rib EE of afh or beech wood is firmly fixed to the middle of the bottom CD, being mortifed into the ends of the ciftern. Thisrib is provided with holes at FF, in which two perpendicular axes are to turn. The lid AB has a rim GG, which links and fits into the ciftern. Two tubes HH are fixed into the lid, their centres being perpendicularly over the cen. tres of the fockets FF when the lid is upon the cif, tern. At 1, is a tube by which the liquor is introduced into the apparatus. As it is neceffary that the space within the rim GG be air-tight, its joints to the lid, and the joints of the tubes, muft be very clofe; and, if neceffary, fecured with pitch. Two perpendicular axes KL, made of afh or beech wood, pafs through the tubes HH, and reft in the fockets FF. A piece of ftrong canvas M is fewed very tight round the axis K, one end of it projecting from the axis. The other axis is provided with a fimilar piece of canvas. NN are pieces of cloth rolled upon the axis L. Two plain pulleys OO are fixed to the axis, in order to prevent the cloth from flipping down. The

shafts are turned by a 'moveable handle P. Qisa moveable pulley, round which paffes the cord R. This cord, which is faftened on the opposite fide of the lid (fee fig. 2.), and paffes, over the fmall pulley S, produces friction by means of the weight T. By the fpigot and fauflet V., the liquor is let off when exhaufted. The dimenfions of this apparatus are calculated for the purpose of bleaching twelve or fifteen pieces of four fourth calicoes, or any other stuffs of equal breadth and fubftance. When the goods are ready for bleaching, the axis L is placed on a frame in an horizontal polizion and one of the pieces N being faftened to the cans vas M by means of wooden skewers, in the mans Her reprefented in fig. 1. it is rolled upon the axis by turning it with the handle P... This operation muft.be performed by two perfons; the one turning the axis and the other directing the piece, which must be rolled on very tight and very even When the first piece is on the axis, the next piece is fastened to the end of it by skewers, and wound on in the fame manner as the first. The fame method is pursued till all the pieces are wound upon the axis. The end of the last piece is then fastened to the canvas of the axis K. Both axes are afterwards placed into the cistern, with their ends in the fockets FF, and the lid is put on the ciftern by paffing the axis through the tubes HH. The handie P is put upon the empty axis, and the pully Q upon the axis on which the cloth is rolled, and the cord R, with the weight T, is put round it and over the pully S. The ufe of the friction, produced by this weight, is to make the cloth wind tight upon the other axis. But as the effect of the weight will increase as one cylinder increases and the other leffen's, Mr Rupp recommends that 3 or 4 weights be fufpended on the cord, which may be taken off gradually as the perfon who works the machine may find it convenient. As the weights hang in open hooks, which are fastened to the cord, it will be little or no trouble to put them on and remove them. Things being thus difpofed, the bleaching liquor is to be tranf ferred from the veffels in which it has been prepared into the apparatus, by a moveable tube passing through, the tube I, and defcending to the bottom of the ciftern. This tube being connected with the veffels, by means of leaden or wooden pipes provided with cocks, hardly any vapours will escape in the transfer. When the apparatus is filed up to line a a a, the moveable tube is to be withdrawn, and the tube I clofed. As the liquor rifes above the edge of the rim G, and above the tubes HH, it is evident that no evapo ration can take place,' except where the rim does not apply clofely to the fides of the box; which will, however, form a very trifling furface if the carpenter's work be decently done. The cloth is now to be wound from the axis L upon the ax K, by turning this; and when this is accomplished, the handle P and pully Q are to be changed, and the cloth is to be wound back upon the axis L. This operation is, of course, to be repeated as often as neceffary. It is plain, that by this procefs of winding the cloth from one axis upon the other, every part of it is expoled, in the most complete manner, to the action of the liquor in which it is immerfed. It will be necef Gggga

fary