are no pores in which the minute grains of the pounded matter may lie concenied. If any fuch matter is to be wathed as is fufpected to contain fome native metal, fuch as filver or gold, a trough foud be procured for this purpofe of a very thallow flope; because the minute particles of the rative metal have then more power to aflemble toputer at the broad end, and separate from the other matter. The management of this trough, or the manner or wathing, is this: When the matter is mixed with about 3 or 4 times its quantity of water in the trough, this is kept very loofe between two frger of the left hand, and fome light ftrokes grea on its broad end with the right, that it may move backwards and forwards; by which means the bearieft particles affemble at the broad and lower end, from which the lighter ones are to be feparated by inclining the trough and pouring a Etle water on them. By repeating this procefs, a tuch particles as are of the fame gravity may be elected together, and separated from thofe of diferent gravity, provided they were before egraly pounded: though fuch as are of a clayey Ba ure, are often very difficult to feparate from the reft, which, however, is of no great confequence to a skilful and experienced wather. The washing procefs is very neceffary, as there are of ten rich ores, and even native metals, found concealed in earths and fand in fuch minute particles as not to be discovered by any other means. CHAP. III. DESCRIPTION of an IMPROVED PORTABLE LABORATORY for aflaying MINERALS. THE chief pieces and implements of the port able laboratories are reprefented in Plate XXIII. at BLOW-PIPE, and in Plate CCXXVI. I. The first contains those belonging to the Dry Iaboratory, fo called on account of its containing whatever is required to try all kinds of foliis in the dry way by fire, without any of the humid mettruums. They are made to pack in a box of the far of an 8vo book, lined with green velvet, and covered with black fish-fkin; the infide divided into different compartments, fuited to the $7c, form, and number of the implements it is to contan. See BLOW-PIPE. The following im provements have been made of that inftrument by Mr MAGELLAN. D and Q (Pl. CCXXVI, fig. 13.) are the two pieces that form the biow-pipe, which is here reprefented entire. This very useful inftrument has been confiderably improved of late in England. The mouth-piece aa is made of ivory, to avoid the disagreeable fenfation of having a piece of metal a long time between the teeth and lips, which, it not of filver or gold, may be very noxious to the operator; a circumftance that has been little noticed before. when it is held between the lips, as may be feen in that reprefented in the figure. 2. The small globe bb is hollow, for receiving the moisture of the breath; and must be compo fed of two hemifpheres, exactly fcrewing into one another in bb; the male fcrew is to be in the lower part, and foldered on the crooked part Q of the tube QD, at fuch a diftance, that the infide end of the crooked tube be even with the edge of the hemifphere, as reprefented by the pointed lines in the figure. But the upper hemifphere is to be foldered at the end of the ftraight tube D. By thefe means, the moisture ariling from the breath falls into the hollow of the lower hemifphere, where it is collected round the upper infide end of the crooked part of the blow-pipe, without being apt to fall into it. 3. The finall nozzles, or hollow conical tubes, advifed by M. Engeftrom, Sir T. Bergman, and others, are wrong in the principle; becaufe the wind that paties from the mouth through fuch long cones lofes its velocity by the lateral friction, as happens in hydraulic fponts; which, when formed in this manner, never throw the fluid fo far as when it paffes through a bole of the same diameter, made in a thin plate of a little inetallic Cap that ferews at the end of the large p. On this account the little cap c is employed, having a fmall hole in the thin plate, which ferves as a cover to it; and there are feveral of there little caps, with holes of finaller and larger fizes, to be changed and applied whenever a flame is required to be more or lefs ftrong. 4. Another convenience of thefe little caps is, that even in cafe any moisture thould efcape falling into the hemifphere bb, and pafs along with the wind through the crooked pipe Q, it never can arrive at nor obstruct the little hole of the cap c, there being room enough under the hole in the infide, where this moisture must be stopped till it is cleaned and wiped out. The ftream of air that is impelled by the blow-pipe (as in tig. 3.) upon the flame, must be constant and even, and mut laft as long as the experiment continues to require it. This labour will fatigue the lungs, unless an equable and uninterrupted infpiration can at the fame time be continued. To fucceed in this operation without inconvenience, fome practical labour is neceflarys Every aflay ought always to begin by the exte rior flame, which must be first directed upon the mais under examination; and, when its efficacy is well known, then the interior blue flam is to be employed. After the ore is roafte', it is to be rounded upon the steel plate by the hammer; the particles being prevented from being diffipated by the ring H (fig. 9, Plate XXIII.) within which the pieces to be broken are put! Among the apparatus, 3 phials are neceiiary, 1. If the mouth-piece aa be made of a round, containing the borax, fal fodæ, and fal fufibile miform, it cannot be held for any length of time be-crocofmicum. Other ufeful articles are, Aimall tween the teeth and lips, to blow through it, link of hard fteel, to try the hardnefs or softness without training the mufcies of the mouth, which of mineral fubftances, and to ftrike fire for lightproduces a painful fenfation. It muft, therefore, ing the candle: A piece of black flint, to ferve as have fuch an external figure, as to adapt itfelf ac- a touch-ftone; for, being rubbed with any metal, curately to the lateral angles of the lips, having a if it be gold, the marks will not be corroded by fattish oval form externally, with two oppofite aqua fortis; and alfo to ftrike fire, when necef ourners to fit those internal angles of the mouth, fary, with the link of steel: An artificial loadstone, VOL. XV. PART I D properly 1 properly armed with iron, for the better prefer- 31. Ferruginous Pruffiate of pot-afh. 32. Lime vation of its attractive power; it ferves to difco- water. 33. Prufliate of lime. 34. Cauftic volaver the ferruginous particles of any ore, after it tile alkali. 35. Mild volatile alkali, dry. 36. has been roafted and powdered: A triple magni- Rectified fpirit, or alcohol. 37. Æther. 38. Spifier, which, differently combined, produces 7 mag- rituous tincture of galls. 39. Spirituous folutions nifying powers, to diftinguish the ftructure and of foap. 40. Syrup of violets. 41. Tincture of metallic parts of ores, and the minute particles of litmus. 42. Tincture of Brafil wood. 43. Tincnative gold: (See Plate CCXVIII. fig. 15.) A file, ture of turmeric. 44. Oil of olives. 45. Oil of to try the hardness of tones and cryftals, &c.: linfeed. 46. Oil of turpentine. 47. Effential fait Some pieces of dry agaric or tinder, and fmall of wild-forrel. 48. Hepar fulphuris. 49. Sugar fplinters of wood tipped with brimstone, to ferve of lead. 50. Solution of alum. as matches. The method of applying the above tests of aII. For performing experiments in the Humid cids and re-agents may be feen in BERGMAN'S Way, the chief additional articles (and which must treatifs of the Analyfis of Waters, and of Affaxing be kept in a feparate cafe,) are, a collection of by the Humid Way; in KIRWAN's Elements of Miphials, containing the principal acids, tefts, pre- neralogy; in the Elements of Chemistry of Dijon; in cipitants, and re-agents, both for examining mi- the Memoirs of the fame Academy; in Foureroy's neral bodies by the humid way, and for analysing Leatures of Chemistry, &c. the various kinds of mineral waters. Those with III. The Lamp-furnace Laboratory, for experiacids and corrofive solutions have not only ground ments both by the humid and the dry way, is a stopples, but also an external cap to each, bound very curious and useful, though finall apparatus, over the stopple, and fecured downward by a bit It is an improvement of one contrived by M. of wax between both, to confine the corrofive and MORVEAU, in confequence of the information he volatile fluids. But thofe which contain mild fluid received from his friend the prefident de Virly, liquors do not need fuch external caps; and those who faw at Upfal how advantageously the late ewith dry inoffenfive fubftances are only stopped minent Sir T. Bergman availed himself of this with corks. There are alfo two fmaller cylindrical convenience for many analytical proceffes in miphials, to exhibit the changes of colour produced nature, by the ufe of very finall glafs veffels aby fome of the re-agents in thofe analytical affays. bout one inch diameter, and other implements of There are alfo two or three fmall matraffes, to proportional fize, for performing various chemihold the fubftances with their folvents over the cal operations. See the Dijon Memoirs for 1783, fire; a finall glafs funnel for pouring the fluids; Part I. p. 171. a fmall porcelain mortar, with its peftle; one or two crucibles of the fame fubftance; a small wooden trough to wash the ground ores; fome glafs fticks to ftir up the fluid mixtures; and, finally, pieces of paper tinged red, yellow, and blue, by the tinctures of Fernambuc wood (commonly called Brafil wood), turmeric, and litmus, thickened with a little starch. The following lift contains the names (chiefly the old names) of the various fluid tefts and reagents neceffary for thefe affays. But the whole number being too large to be all contained in a portable cafe, every one may give the preference to thofe he likes beft. 1. Concentrated vitriolic acid, whose specific gravity may be expreffed in the outside. 2. Nitrous acid, purified by the nitrous folution of filver. 3. Concentrated marine acid, with its fpecific gravity. 4. Marine acid dephlogifticated. 5. Aqua regia for gold, viz. z. nit. and I marine. 6. Aqua regia for platina, viz. half marine and half nitrous acid. 7. Nitrous folution of filver. 8. Nitrous folution of mercury, made in the cold. 9. Muriatic folution of barytes. 10. Nitrous folution of lime. II. Muriatic folution of lime. 12. Mercury in its metallic ftate. 13. Corrofive fublimate of mercury. 14. White arfenic. 15. Nitrous folution of filver. 16. Nitrous folution of copper. 17. Acid of fugar. 18. Liquor probatorius vini. 19. Hepar fulphuris. 20. Oil of tartar per deliquium. 21. Salt of tartar. 22. Cauftic vegetable alkali. 23. Pearl-athes. 24. Soap maker's ley. 25. Common falt. 26. Vitriolated argilla, or alum. 27. Vitriol of iron, or copperas. 28. Nitrous folution of filver. 29. Acetous folution of lead. 35. Acetous folution of barytes. When these proceffes are properly conducted, though in miniature, the lamp furnace will prove amply fufficient to perform in a few minutes, and with very little expence, the various folutions, digeftions, and diftillations, which otherwife would require large veffels, fills, retorts, reverberatory furnaces, &c. to afcertain the component parts of natural bodies; though it is not always fufficient to afcertain their respective quantities. In this last cafe, operations must be performed in great laboratories, and on a large fcale, at a confiderable expence. But the fubitances are fometimes too valuable; for inftance, when precious ftones are to be examined, the laft way never can be attempted. Thefe fmall proceffes have likewife another advantage which cannot be obtained in large works, viz. that one can obferve the gradual progress of each operation; retard or urge it, as it may require; and afcertain at pleasure each step of every experiment, with the phenomena attending it. The lamp furnace is mounted in a very finall parallelogram of mahogany, about 6 inches long and 4 wide: See fig. 5. pl. CCXXVI. This is kept fteady over the edge of a common table, by means of the metallic clamp suw, which is faftened by the fcrew x. The pillar rs is fcrewed in a vertical pofition on the plate s, being about ten inches high; the other is screwed to the oppofite corner marked pk, and is only 7 inches long; both are compofed of two halves, that fcrew at tt, to be eafily packed up with all the implements in a case covered with black fifh fkin, and lined with green velvet, like the other laboratory already defcribed. The lamp k, fig. 3. is fupported on the plate ar which has a ring / that runs in the column pk, and may be fixed by its ferew / at the required height. This lamp has 3 fmall pipes of differ. ent fizes, to receive as many wicks of different thicknefs, and to be filled with spirit of wine. By a finar method, a piece of charcoal is mounted upported by the pliers or little forceps fcrewed to the arm ar, fig. 1. which has all the motions requifite for being fixed by means of proper fer ws, at a proper diftance from the flame of the wirk. The blow pipe, fg. 4. s, by a fimilar mechanim, mounted on the fmailer column pq, at fuch ad ftance as to blow the flame bi to the piece of ore m, which is upon the charcoal gf. Everthing being disposed in this manner, the operit blows through the mouth piece of the bow pipe, fig. 4. and remains with his hands free to make the changes and alterations he may think proper. N. B. The large round cavity e in the mick of the parallelogram, fg. 5. is to receive the lamp k, fig. 3. when all the implements are packed up in their cafe of black fish-skin; and the cover of the lamp is reprefented by fig. 12. but if the operator has the double bellows, fig. 14. and 15. he fixes them, at a due distance, to the fame table by the brafs clamp y. He then unicrews the blow pipe at zz. joins the mouth of the flexible tube to the hemifphere z z, paífing each orifice, through the ieather tube fig. 11. and tying both ends with a waxed thin packthread. If he works with his foot on the pedal, the firing of which is feen hanging from the end of the bellows, fig. 15. (and is always up, on account of the weight e), then the air is abforbed by the bellows fig. 15. from whence it is propel led by the motion of the foot on the pedal to the bellows, fig. 14. whofe conftant weight drives it urt through the flexible pipe, fig. 10. It of courfe tra the curbed part zzi of the blow pipe, and drives the flame on the piece m of the ore, that is to be examined upon the charcoal. N. B. 1. Toubie bellows is packed up by itfelf in a mabigin cafe, about 9 inches long, 64 wide, and abstdeep outfide measure. 2. The laft blowing blows, fig. 14. has an infide valve, which opas when the upper furface of it is at its greatcit height; in order to let the superfluous air efcape cat, as it would otherwife iffue with great velocity out of the tube fig. 11. and spoil the operation. cording to the method of Mr WILLIS, described in the Tranfactions of the Society of Arts, Voi. V. p. 96. This laft confifts in diffolving 2 oz. of borax in a pint of boiling water, and adding to the folution as much flacked lime as is necessary to form a thin pafte. This glafs retort is to be covered all over with it, by means of a painter's brush, and then suffered to dry. It must then be covered with a thin pafte made of linfeed oil and flacked lime, except the neck that enters into the receiver. In two or three days it will dry of itfelf; and the retort will then bear the greatest fire without cracking. Two ounces of good ritre, urged in the retort, by a good fire on a chaffingdish, will afford about 700 or 800 ounce measures of oxygenous air. To make any other kind of chemical affays, the forceps of fig. 2. which fupports the charcoal, is taken off, by unfcrewing the fcrew b; the blowpipe is also taken off, by loofening the fcrew n; the hoop fig. 7. is put in its place, where the metallic bafia fig. 19. is put filled with fand: the piece of fig. 8. is fet on the other pillar rs, fig. 1. to hold the matrafs, fig. 18. upright, or the receiver fig. 20. &c. In the fame manner, the retort, fig. 9. may be put in the fand bath instead of the matrafs, with its receiver fig. 20. which may be supported on a bit of cork or wood, hollowed to its figure, and held by the pliers, inftead of the charcoal fig. 2. But if the operation is to he made in the naked fire, the neck of the retort, fig. 9. being luted to the receiver, or balloon, fig. 20. may be hanged by a little chain with its ring over the flame, being fufpended from the piece of fig. 8 or 7. fcrewed to either of the pillars as may be moft convenient. Otherwife the receiver, fig. 20. may be fupported by the round hoop of brafs, fig. 7 or 8. fcrewed at a proper height to the pillar, fig. 1. tying round it fome packthread to defend the glafs from the contact with the metallic fupport. The piece of fig. 6. may be forewed by its collar and ferew of to any of the pillars; carrying with it the retort and its receiver, at proper diftances, higher or nearer to the lamp, according as the flame is more or lefs violent. Thefe implements afford all forts of conveniences for making any kind of fmall operations and affays in miniature, provided the operator pays a proper attention to the difpofition requi fite for each process or operation. Glafs retorts, receivers, matraffes, bafins, fmall funnels, &c. are made by the lamp workers, that blow beads, thermoters, and other imali glass inftruments. If the operator chooses to apply vital air in his proceís, let him fill the glass-jar b, fig. 17, with this air: and put it within the tube marked abze, filled with water, fastening the neck of the jar within by cross-board ed, which has a hole in it for that purpose; then introducing the two ends of the flex-The lamp k, fig. 3. fhould be filled with spirit of ice hollow tube, fig. 16. both to the mouth of the wine, because it gives no difagreeable smell; does jar and to the hole of the bellows fig. 15. he opens not produce any fuliginous cruft on the veffels as the hole m of the jar, that was stopped with the oil does; and gives a dry flame, without smoke, Ropple; the column of the water paffes in thro' and stronger than oil. M. de Morveau adds, that , and forces up the vital air, which enters the bel- the expence of spirit is quite inconfiderable; and lows, and of course, by the alternate motion of the that he performed in 8 or 10 minutes with this pedal, paffes through the end of the blow-pipe, to apparatus, various diffolutions, evaporations, and urge the flame upon the piece of ore m, fig. 2. on other proceffes, which otherwife would have tathe charcoal g. But the vital air may be alfo re- ken more than three hours, with the expence onceived at the fame time that it is produced, by ly of two or three halfpence for the fpirit of wine, fying the pipe, fig. 16. to the mouth of an earthen whilft the fuel of charcoal would have coft near retort, or even of a glafs retort well coated, ac- ten or eleven pence. ner, unless there be a peculiar term, for each of their properties, and unless this term be completely understood. Mineralogy therefore must have a language of its own;-it muft have a term to denote every mineralogical property, and each of thefe terms must be accurately defined. The language of mineralogy was invented by the celebrated WERNER of Freyberg, and first made known by his treatife on the External Characers of Minerals. Of this language the following general defeription of the properties of minerals will convey an idea. MORYFAU jufly obferves, that many philo- ties. The fmaileft deviation from this would fophers do not apply to chemical operations, for lead to confufion and uncertainty. Now it want of opportunity of having a laboratory to per- is impoffible to defcribe minerals in this manform them; as it requires a proper room, and great expences, of many large furnaces, retorts, crucibles, and numerous other implements, &c. But thefe miniature laboratories in a great meafure afford every advantage, at leaft to that degree of fatisfaction fufficient to afcertain the contents and products of any fubftance subjected to trial; for with this fimple apparatus a man of ordinary abilities may, without embaraffinent, in a very short time, and with little expence, perform fuch diftillations as require a reverbatory furnace; all forts of proceffes, digeftions, and evaporations, which require a regular fand heat; he may vary his experiments or trials, and multiply them to a great number of various performances, draw up his conclufions, and reafon upon them, without lofs of time, without the hindrance of long preparations to work at large. And even when fach large works are to be performed, he may obferve beforehand various phenomena of fome substances, which, if not known in time, would impede the proceffes at large, or make them fail abfolutely; and all this without the risk of a confiderable lofs, and without expofing himself to a great fire, &c. PART II. OF THE DESCRIPTION AND ARRANGE- THE most accurate, methodical, and complete Defcription and Arrangement of Minerals we have yet met with, are thofe of the ingenious Dr THOMAS THOMSON of Edinburgh; inferted in his System of Chemistry, Vols. III and IV. 1802. We shall therefore ufe the freedom to quote that excellent work fo far as it refpects thefe topics, as the beft treatife we can prefent to our readers on the subject of mineralogy, without prefuming to make any material alteration, except leaving out his authorities and most of his notes; and abridging a little where the language can poffibly admit of it. If the Doctor's fyftematic arrangement can admit of any improvement, perhaps it might be by giving names to the different genera of earths and ftones, inftead of expreffing their titles by fymbols. (See Chap. IV.) But this we leave to future mineraloguts to determine. CHAP. I. Of the DESCRIPTION of MINERALS. "Nothing, at first fight, appears eafier, than to defcribe a mineral, and yet, in reality, it is at tended with a great deal of difficulty. The mineralogical deferiptions of the ancients are fo loose and inaccurate, that many of the minerals to which they allude cannot be afcertained; and confequently, their obfervations, however valuable, are often, as far as refpects us, altogether loft. It is obvious, that to diftinguith a mineral from every other, we muft either mention fome peculiar property, or a collection of properties, which exift together in no other mineral. Thefe properties must be deferibed in terms rigidly accurate, which convey precife ideas of the very properties intended, and of no other proper "The properties of minerals may be divided into two claffes. 1. Properties difcoverable without deftroying the texture of the mineral; 2. Properties refulting from the action of other bodies on it. The first clafs has, by WERNER, been called external, and by fome French writers phyfical the 2d chemical. "The external properties may be arranged under the following heads: 1. Figure. 2. Surface. 3. Transparency. 4. Colour. 5. Scratch. 6. Luftre. 7. Hirdnefs. 8. Ductility. 9. Fracture. 10. Texture. 11. Structure. 12. Fragments. 13. Feel. 14. Sound. 15. Smell. 16. Tafte. 17. Gravity. 18. Magnetifm. 19. Electricity. "1. By FIGURE is meant the flape or form, which a mineral is obferved to have. The figure of minerals is either regular, particular, or amorphous. 1. Minerals which affumne a regular figure are said to be crystallized. The fides of a crystal are called faces; the fharp line formed by the inclination of two faces is called an edge; and the corner, or angle, formed by the meeting of feveral edges in one point, is called a solid angle, or fimply an angle. Thus a cube has 6 faces, 12 edges, and 18 angles. 2. Some minerals, though not cryftallized, affect a particular figure. These figures are the following: Globular, like a globe; oval, like an oblong spheroid; ovate, like an egg; cheefe-fhaped, a very flattened fphere; almondJhaped, like an almond; lenticular, like a double convex lenfe, compreffed and gradually thinner towards the edges; cuneiform, like wedge; nodulous, having depreflions and protuberances like a potatoe; botryoidal, like grapes clofely preffed together; dentiform, longith and tortuous, and thicker at the bottom than the top; suir form, like a wire; capillary, like hair, finer than the preceding; retiform, threads interwoven like a net; dendritic, like a tree, having branches itfuing from a common ftem; shrubform, branches not arifing from a commou ftem; coraloidal, branched like coral; ftalactitical, like icicles; clavated, like a club, long, and thicker at one end than another; fafciform, long, straight, cylindri cal bodies, united like a bundle of rods; tubular, cylindrical and hollow. 3. When minerals have neither a regular nor particular fhape, they are faid to be amorphous, a "II. By SURFACE is meant the appearance of the external furface of minerals. The furface is either uneven, composed of finall unequal elevations and deprefiions; fabrous, having very small harp and rough elevations, more cafily felt than 66 a mixture feen; drufy, covered with very minute crystals; of brown. Afaragus g.: the lighteft g. yellowragh, composed of very minute blant elevations, ith with a little brown and grey. any ditin ruithable by the fe fealy, compofed "6. Yellors. Sulphur y.: a light greenish y. of very minute thin feale-like laves; fmooth, free Brafs y.: the preceding with a little lefs green and from all inequality or roughnels: fpecular, having a metallic iuftre. Lemon y.: Pure y. Goid y.: a mouth polished furface like a mirror; or freak- the preceding with a metallic luftre. Honey y.. ed, having elevated, ftraight, and paralic lines. a deep y. with a little reddish brown. Wax y.: This last character is confined to the surface of the preceding, but deeper. Pyritaceous y.: a cryftals. The ftreaks are either tranfverfe; longi pale y. with grey. Straw y.: a pale tudinal; alternate, in different directions on differ- of fulphur y. and reddith grey. Wine y. a pale ent faces; phomafe, rupning from a middle rib; y. with a tint of red. Ochre y.: darker than the or derated, crolling each other. preceding, a mixture of lemon y. with a little brown. Ifabella y.: a pale brownish y. a mixture of pale orange, with reddish brown. Orange y.: a bright reddish y. formed of lemon y. and red. 7. Reds. Aurora r.: a bright yellow r.: a mixture of fearlet and lemon yellow. Hyacinth r.: a high r. like the preceding, but with a fhade of brown. Brick r. lighter than the preceding, a mixture of aurora r. and a little brown. Scarlet r.: a bright and high r. with fearse a tint of yellow. Copper r. a light yellowifh r. with the metallic luftre. Blood r.: a deep r. a mixture of crimson and fearlet. Carmine r.: pure r. verging towards a caft of blue. Cochineal r.: a deep r.; a mixture of carmine with a little blue and a very little grey. Crimson r.: a deep r. with a tint of blue. Flesh r.: a very pale r. of the crimson kind. Rofe r.: a pale r. of the cochineal kind. Peach bloffom r.: a very pale whitifh'r. of the crimson kind. Mordoré, a dark dirty crimson r. a mixture of crimson and a little brown. Brownish r.: a mixture of blood r. and brown. Ill. By TRANSPARENCY is meant the proportion of light which minerals are capable of tranfmitting. They are transparent or pellucid when betts can be feen diftinctly through them; diapers, when objects arefeen thro' them indiftinctsy: ubdiaphanous, when light paffes, but in fo dalla quantity that objects cannot be feen thro' them; opaque, when no light is tranfmitted.-I have denoted 3 degrees of tranfparency by the figures 4, 3, 2. when a mineral is fubdiaphanous only at the edges, that is denoted by the figure 1. Opseity is denoted by o.-When opaque mine rais become transparent in water, they are called Androphanaus. When objects are feen double through a transparent mineral, it is faid to re fred doubly. “IV. The Colours of minerals may be reduced to 8 claffes: 1. Wortes. Snow white: pure white. Reddith w.: White with a light tint of red. Yellowifh w.: White with a light tint of yellow. Silver w. Yellowith w. White with a metallic luftre. Greyish w. White with a light tint of black. Greenith w. White with a light tint of green. Milk w. White with a light tint of blue. Tin w. Milk w. of a metallic luftre. 2. Greys. Bluish g.: Grey with a little blue. Lead g.: bluish g. with a metallic luftre. Pearl g.: Light g. with a flight mixture of violet blue. Smoke g.: dark g. with a little blue and brown. Greenish g.: light g. tinged with green. Yellow. hg.: a light g. tinged with yellow. Steel g.: a dark g. with a light tint of yellow and a metalhe letre. Black g. the darkest g. with a tint of yellow. 3. Blacks. Greyifh black: Black with a little white. Brownifh b.: black with a tint of brown. Black: pure b. Iron black: pure b. with a small mixture of white and a metallic luftre. Bluifh b.; black with a tint of blue. 4. Bls. Indigo blue: a dark blackish b. Pruffian b.: the pureft b. Azure b.: a bright b. with fcarce a tint of red. Smalt b.: a light b. Violet b.: a mixture of azure b. and carmine. Lavender b.: violet b. mixed with grey. Sky b.: a light b. with a flight tint of green. 66 5. Greens. Verdigris green: a bright g. of a bluifh caft. Sea g.: a very light g. a mixture of verdigris g. and grey. Beryl g. the preceding, but of a yellowish caft. Emerald g.: pure g. Grafs 8. pure g. with a tint of yellow. Apple g.: a fight g. formed of verdigris g. and white. Leek .: a very dark g. with a caft of brown. Black ith g. the darkeft g. with a mixture of leek g. and black. Piftachio g.: Grafs g. yellow and a little brown. Olive g.: a pale yellowish g. with a tint "8. Browns. Reddish b.: a deep b. inclining to red. Clove b.: a deep b. with a tint of carmine. Yellowish b. a light b. verging towards ochre yellow. Umber b.: a light b. a mixture of yellowifh b. and grey. Hair b. intermediate between yellow b. and clove b. with a tint of grey. Tombac b.: a yellowish b. of a metallic luftre, formed of gold, yellow and reddish brown. Liver b.: a dark b.; blackifh b. with a tint of green. Blackifh b.: the darkest brown. "Colours, in refpect of intensity, are either dark, deep, light or pale. When a colour cannot be referred to any of the preceding, but is a mixture of two, this is expreffed by faying, that the prevailing one verges towards the other, if it has only a small tint of it; paffes into it, if it has a greater. "V. By the SCRATCH OF STREAK, is meant the mark left when a mineral is fcratched by any hard body, as the point of a knife. It is either fimilar, of the fame colour with the mineral, or diffimilar, of a different colour. The "VI. LUSTRE is the glofs or brightness, which appears on the external furface of a mineral, or on its internal furface when fresh broken. firft is called external, the 2d internal luftre. Luf tre is either common, that which most minerals poffefs; filky, like that of filk or mother-of-pearl; waxy, like that of wax; greafy, like that of grease; or metallic, like that of metals. As to the degree, the greateft is called fplendent; the next shining; the 3d dullish; and when only a few scattered particles fhine, the luftre is called dull. Thefe degrees are noted by the figures, 4, 3, 2, 1, and no luftre by o. "VII. I have ufed Mr KIRWAN'S FIGURES to denote |