Elements of Mineralogy

Part II. Saline Substances

CHAP. I. FACF Acids , 1 CHAP. II. Alkalis 5 CHAP. III. Neutral Salts ib. Species 1 . Tartar Vitriolate 8 2. Glauber's Salt 9 3. Vitriolic Ammoniac IO 4. Epsom Salt 11 5. Alum 12 6. Aluminous Ores 14 Stony ; 10 Earthy 17 Family 1. Slaty ib. 2. Compact 18 3. Ligneous 19 7. Vitriol of Iron ib. 8. - of Copper 20 Q. of Zinc '. 22 10. Mixed, Iron, Copper and Zinc 23 1 1. Nitre , ib. 12. Nitrated Soda 26 13. Nitrous Ammoniac ib. 14. Nitrated Calx TJ 15. Nitrated Magnesia ib. 16. Muriated Tartarin 28 17. Common Salt ib. Variety 1. Lamellar 29 2. Fibrous ib. tot. ir, a Species CONTENTS. VI PAGB Species 1 8. Sal Ammoniac 30 19. Muriated Barytes 31 20. Calx ib. 21. Magnesia 32 22. Argill ib. 23. ■ Iron 33 24. Copper ib. 25. Magnesia ib. 26. Tinc.il ib.

Part III. Inflammable Substances

3a Genus 1. Inflammable Air ib. 2. Bituminous 37 Species 1 . Naphtha ib. 2. Petrol 38 3. Mineral Tar 39 4. Titch ib. Variety 1. Cohesive 40 2. Maltha ib. 3. Asphalt vb. 5. Mineral Tallow 41 Mineral Cahoutchou 42 Genus 3. Carbonaceous Substances ib. Species 1. Native Carbon ib. 2, Bituminous Carbon 45 Family 1. Cannel Coal ib. Variety 1 . Compact ib. 2. Slaty 46 Family 2. Impregnated with Asphalt "1 ■, and Maltha . , j / **' Variety 1. From Whitehaven 47 2. Wigan ib. .". ■ Swansea 48 4. Leilrim ib. 5. Irvine H-. Family 3. Spurious Coal 49 3, Antracolite H. 4. Plumbago ib. Genus 4, Vegeto Carbonated Substances 51 Species 1. Cubonated Wood ih, Variely 1. Lignilorm jh. 1. Sc.ily or Earthy 52 3. Compact ih. ib. 2. Turf and Peat . 53 Genus CONTENTS. VII PAGE Genus 5. Vegeto Bituminous 54 Species 1 .

Jet ib. 2. Amber 55 Of Ambergris and Copal 56 Appendix. Mellilite 58 Genus 6. Sulphur and its Ores ib. Species 1. Native Sulphur ib. 2. Hepatic Air 62 3. Sulphur combined with Argill ib. 4. ■ mixed with Argill 63 5. Uniled to Calcareous Earth . . . .v ib. 6. to Fixed Alkalis ib. 7 . to Metallic Substances 64 S. Martial Pyrites ib. Family 1. United to Iron in its Metallic state 65 Variety 1. Common Sulphur Pyrites .. ib; 2. Striated ib. 3. Capillary 67 4. Magnetic ib. Family 2. United to Calx of Iron .... 70 Hepatic Pyrites ib. Analysis of Pyrites 73 73

Part IV. Metallic Substances

76 CHAP. I. Gold 80 Species 1. Native Gold 81 Auriferous Ores 83 CHAP. II. Platina , QO CHAP. III. Silver and its Ores 94 Species 1 . Native Silver ib. Family 1 . Pure 95 2. Auriferous ib. 3. Cupriferous 96 4. Antimoniated ib. 5. Arsenicated 97 2. Calciform . . .'. 98 3. Mineralized by Acids ib. Family 1 . Corneous ib. 2. Argillo Muriated 100 a 2 Species CONTENTS. PABJ Species 4. Sulphurated Silver Orr 10(» 5. Li jilt Lamellar Silver Ore 101 6. Sooty Silyer Ore 102 7 . Antimoniated Silver Ore d'- 8. Plutubiferous Antimoniated Silver Ore 103 Family 1 . Light Grey ib. 2 Dark Grey lot 9- Cupriferous Sulphurated Silver Ore .... ib. 10. Red Silver Ore 105 Family 1. Light Red 106 2 Ha, k Red 107 1 1 . Scoriaceous 1 03 12. Bismuthic ib. 13. Greenish and Reddish Black Silver Ore ib. Subsidiary Ores 109 CHAP. IV.

CorriR and its Orfs 110 Species 1. Native Copper Ill Variety I . ib. 2. Cement Copper ib. 2. Calciform Copper Ores 112 Tribe 1 Blue ib. Variety 1 . Mountain Blue ib. 2. Siriated 113 Tribe 2. Grren ib. Family 1 . Malachite 114 Variety .1 . Fibrous ib. 2. Compact 115 Family 2. Mountain Green ib. Tribe 3. Red 117 Family 1 . Cochineal Red ib. Variety 1 . Compact ib. 1. Foliated ib. 3. Fibrous U8 Family 2. Brick Red ib. Variety 1 . Earthy ib. 2. Indurated '. . . 119 3. Mineralized by Sulphur 120 Family 1. Copper Pyrites 121 2. Purple ] 22 3. Black 124 4 1 Vitreous ib. Variety 1. Compact ib. 2. Foliated 126 i .hoi'y 5. Grey ib. Species CONTENTS. IX PAGE Species 4. Mineralized by Muriatic Acid 129 5. Mineralized by Arsenical Acid 0 Olive Copper Ore ib. Earthy Iron Shot Mountain Green .... 131 Glassy Iron Sfcot Mountain Green . . ib. 6.

Mineralized by Arsenic White Copper ib. Various Cupriferous Compounds 132 CHAP. V. Iron and its Ores 133 Species 1 . Native Iron 134 2. Mineralized by pure Air 135 Tribe 1 136 Family 1 . Common Magnetic Iron Stone ib. 2. Fibrous 138 3. Magnetic Sand ib. Tribe 2 139 Family 1 . Specular Iron Ore ib. 2. Brown Hæmatites 140 3. Compact Brown Iron Stone . . 142 4. Brown Scaly Ore . , 143 5. Brown Iron Ochre ib. 6. Black Iron Slone 144 Tribe 3 145 Family 1 . Red Hremnlites ib. 2. Compact Red Iron Stone .. 146 3. Rrd Ochre 14? 4. 1 d Scaly Iron Oe ib. Tribe 4. Argillaceous Iron Ores .... 148 Family 1. Up'and ib. Arghacious ib. Variety!. Common Ar6illaceous Iron I -, Stone J 2. Columnar Iron Ore 151 3. Acinose 152 4. Nodular ib. 5. Pisiform 153 Family 1. Low land Argillaceous Iron Ore ib. Of Siderite 154 Sideritic Calx ib.

Variety 1. Of Lowland Ores Meadow 156 2. Swampy 157 3. Morassy 158 3. Mineralized by Carbon ib. Plumbaginous , ib. 4. Blue Martial Earth 159 5. Blue Iron Ote of Vorau 160 a 3 Species CONTENTS. X PAGE Species 6. Green Martial Earth 16 1 7. Mineralized by Sulphur 1 62 8. Mineralized by Arsenic ib. 9. Mineralized by the Arsenical Acid .... ib. 10. Sparry Iron Ore ib. 1 1 . Emery 1 65 12. Tungstenic Iron Ore 166 CHAP. VI. Tin and its Ores 167 Species 1 . Native Tin ib. 2. Mineralized by Oxygen 1 1 8 Family 1. Common Tin Stone ib. 2. Fibrous, or Wood Tin Ore 1/0 3. Tin Pyrites 171 CHAP. VII. Lead and its Ores 1 73 Species 1. Native Lead ib. 2. Mineralized by Oxygen and Fixed Air 174 Family 1 . White Lead Oie ib. 2. Earthy, Yellowish, Green- ~| „ ish, &c. Lead Ore ...... / ]/5 3. Earthy Red Lead Ore 1 76 3.

Phosphorated Lead Ore 177 4. Arsenicated Lead Ore 179 5. Arsenico Phosphorated ] £0 6. Vilriolated 181 7. Yellow Mclybdenated Lead Ore 1S2 8. Red Lead Spar 1 S3 9. Mineralized by Sulphur 185 Family 1. Common Galena jb. 2. Compact 1 S7 3. Blue Lead Ore is8 4. Black Lead Ore Ign Of the Brown Lead Ore of Werner ii, it. CHAP. VIII. Mercury and its Ores ]00 Species 1 . Native 2Q1 2. Natural Amalgama J/, 3. Mineralized by Oxygen 1q2 Family 1 . Compact ,- \ti. .family 1. Compact ,- j£# 2- Slaty '."'/ 1£3 4. Corneous Mercurial Ore .... it. 5. Mineralized by Sulphur .... 194 Family 1. Native Æthiops ;/.. it. Family CONTENTS. XI PAGE Family 2. Native Cinnabar 194 Dark R.-d ib. Bright Red 195 3. Greyish Black 1QJ CHAP. IX. Zinc and its Ores ib. Species 1. Calamine 198 Family 1 . Loose , 1 99 2. Compact ib. 3.

Striated 201 2. Blende 203 Family 1. Yel'ow ib. 2. Brown 204 3. Black 205 CHAP. X. Antimony and its Ores . . .%, 208 Species 1 . Native 209 2. Sulphurated 210 Family 1 . Compact 211 2. Foliated ib. 3. Striated 212 3. Sulphurated and Arsenicated Antimonial "1 .. Ores / 4. Red AntimonialOre 213 5. Muriated ib. Antimonial Ochre 214 Supposed Phosphorated Antimony 215 CHAP. XL Arsenic AND its Ores 2l6 Species 1. Native Arsenic 217 2. Do. Alloyed with Iron 218 3. Do. with Sulphurated Iron 219 4. Mineralized by Oxygen 220 Loose ib. Indurated ib. S. Mineralized by Sulphur 221 Family 1. Orpiment ib. 2. Realgar 222 GHAP. XII. Bismuth and its Ores 223 Species 1. Native ,,.... • 224 Species CONTENTS. XII PAGE Species 2. Bismuth Ochre 224 Earthy ib. Crystallized 225 3. Mineralized by Sulphur ib. CHAP. XIII.

Cobalt and. its Ores 226 Species. 1 . Dull Grey Cobalt Ore 228 2. Bright White Cobalt Ore 23 1 3. Mineralized by Oxygen 233 — j j o — - Family r. Black Cobalt Ore ib. Loose ib. Indurated ib. 2. Erown 234 3. Yellow ib. 4. Red Cobalt Ore 235 Family 1 . Cobaltic Germinations .... ib. 2. Cobaltic Incrustations 236 Green and Violet CcLalt Ores 237 CHAP. XIV. Nickel and its Ores ib. Species 1. Native Nickel alloyed by Iron 239 2. Nickel Ochre, and Vitriol, Loose .... ib. Indurated 240 3. Arsenicated Nickel ib. 4. Sulphurated Nickel 241 CHAP. XV. Manganese and its Ores 243 Species 1 . Native 246 2. Mineralized by Oxygen ib. Family 1 . Grey ib. 2. Black 248 Earthy it. Indurated 249 3. Mineralized by Oxygen and Fixed Air 251 Family 1 . White , ib. 2. Red 252 4. Vitriolated Manganese 255 CHAP. XVI. Uranite and its Ores H. Species 1.

Mineralized by Oxygen 256 Family CONTENTS. xiii PAGE Family 1 . Uranitic Ochre 257 2. Micaceous 258 Species 2. Sulphurated 259 CHAP. XVII. Tungstenite and its Ores 26l Species 1. Tungsten 266 Family 1. White or Grey ib. 2. Brown 267 2. Wolfram 26S CHAP. XVIII MoLYsSDENITE 270 Molybdena ib, CHAP. XIX. Sylvanitb 275 CHAP. XX Menachanite 277 CFIAP. XXI. Titanite 279 Calcareo Siliceous Ore 282 CHAP. XXII Of the determination of an Ore from its ex- "1 ternal Characters j Section 1. Analysis of Ores of Silver 293 2. Copper 3 1 6 3. Iron 330 4. Tin 33y 5. Lead 34(3 fi. Mercury. 36l /. Zinc 364 8. Antimony 37 1 Q. Arsenic _. 375 10. Bismuth 379 11. Cobalt 380 12. Nickel 389 j 3. Manganese 396 14. Uranite 404 15. Tungstenite ' 407 10. Molybdenite ' 413 GENERAL CONTENTS. GENERAL METHOD OF ASSAYING ALLOYS IN THE DRY WAY.

I. Table of the composition of Metallic Calces 2. Metallic Salts 3. the proportion of Sulphur in Sulphurated Metals Analysis of Coals. ELEMENTS ELEMENTS OF MINERALOGY.

PART II. SALINE SUBSTANCES.

4 LL thole substances that are arranged under "^ this denomination, require less than 200 times their weight of water to dissolve them. CHAP. I. OF ACIDS. The Acids that occur in the Mineral Kingdom, either disengaged or combined, are, 1st, The Aerial, otherwise called Carbonic Acid, or fixed air. 2nd, The Vitriolic. 3d, The Nitrous. 4th, The Marine or Muriatic. 5th, The Sparry or Fluor. 6th, The Phos phoric. 7th, The Arsenical. 8th, The Bovol. n. b racic. racic. 9th, The Molybdenous. 10th, The Tungstenic. 11th, The Suecinous. The Aerial Acid is found either in an aerial state, as in mines, caverns, volcanic craters, pits, wells, or combined with water, in mineral or common springs, or with various earths, as the calcareous, barytic, stronthian, muriatic, and argillaceous, or with metallic substances, as in various ores.

It is sufficiently distinguished by its inability to support life, or flame, its ability to unite with water, and of precipitating lime from lime-water in an effervescent state, and its inability to effect a precipitation of lime from its solution in any other acid. The Vitriolic Acid is capable of existing at least in two states, namely, the imperfectly acidified, and then called the sulphureous acid, or the perfectly acidified, forming the common vitriolic acid, simply so called. The sulphureous acid exists, disengaged in the craters of volcanos, in various solfaterras, and in, and over, hot waters in the neighbourhood of volcanos, or exhaling from recent lavas. The common vitriolic acid, I believe, has never been found in nature free from all combi nation, though it may unite to some bodies beyond the point of saturation.

It is true, Mr. Baltassari says, he found some dry concentrated vitriolic acid adhering to selenite, in a grotto in Monte Zaccolino, near Sienna ; but this has been fully disproved by the subsequent ob servations of Mr Murray, in the Slth vol. of the Memoirs of Stockholm, and of Mt. Dolo mieu, in his Notes on Bergman de Prod. Volcan.. p. 88. In a combined stale it is found iu various salts, earths, and ores. The Sulphureous Acid in an ai rial stale, is ACIDS is distinguishable by its peculiar smell, its prompt absorbability by less than one-half its bulk of water, the smell it then communicates to it, the immediate precipitation of lime-water, as well as the discoloration of syrup of violets, which water thus impregnated can effect. The Nitrous Acid, has, I believe, been never found in a free state, except perhaps in charnels and privies, and though generally formed of pure air, and mephitic air furnished by putrefy ing substances, yet, as it has been found in neutral salts, so circumstanced that putrefaction can scarce be suspected to have taken place, and has also been lately artificially formed by Dr. Milner, without any preceding putrefac tion ; we can no longer deny it a place among the mineral acids.

The Muriatic Acid, frequently occurs in a combined state, either with alkalis, earths, ot metals. The Sparry Acid, exists principally in fluor spar, yet some other stones, and even some metallic ores, are often partially impregnated with it. The Phosphoric Acid, is frequently found in a state of union, not only with calcareous earth, but also with various metallic substances. The Arsenical Acid, has been traced in the ores of other metallic substances, particularly of cobalt and copper. The Roracic Acid, has been found in a disengaged state in the waters of several laguni, or lakes of hot mineral waters, near Monte Rotondo, Berchiaio and Castellonuovo in Tus cany, in the proportion of nearly nine grains in one hundred of water, by Mr. Hoeffer. Mr. Mascagni has also found it adhering to^shisti, b 2 on on the borders of lakes, of an obscure white, yellow or greenish colour, and crystallized in the form of needles. 16 Roz. p. 364!

In a combined state, it has been found not only in union with soda, but also with calx and mag nesia, as already seen. And according to Mas cagni, also with Volalkali. 42 Roz. p. 37. In its free state it is distinguishable by its flaky appearance, its solubility in less than twenty times its weight of boiling water; from whence, on cooling, it precipitates for the most part, and crystallizes in light white shining flakes, which when heated, tumefy and vitrify, but the glass thus formed, is again soluble in water as before. The aqueous solution red dens litmus, but more difficultly and transiently syrup of violets. This acid is also soluble in spirit of wine, to whose flame it communicates a greenish tinge. Its specific gravity is 1,479. The Molybdenous Acid, has been exti'tu-ted from molybdena, and also been found com bined in some lead ores.

The Tungstenic Acid, has been found com bined with calcareous earth in Tungsten. The Succinous Acid, has been found in mi neral coal. Mem. Paris, 1781, p. 211. chap. j CHAP. II. OF ALKALIS. Of these there are two kinds, the fixed and the volatil. Of the fixed there are two species, the one generally afforded by the incineration of inland vegetables, and thence called the Vegetable Alkali, (which I call Tartarin), the other, extracted from some maritime plants, but most frequently of mineral origin, and thence called Mineral Alkali, or Soda, or Natron. Neither of them is found perfectly disengaged from acids, but combined, at least with fixed air ; hence, combined with this air they effervesce with other acids, turn syrup of violets and in fusions of turnsole green, and crystallize with the vitriolic, nitrous and marine acids, precipitate earthy and metallic solutions, &c. Tar tarin combined with fixed air is seldom found in the earth, except in wells in towns, as at Dowajr, &c. 4 Mem.

Scav. Etrang. yet it is said to exist in the aluminous ore of La Tolfa; and in combination with the vitriolic, nitrous and marine acids, it is found in Spain, and the East Indies, as will presently be seen. Indeed, from Mr. Bowles's account, it would seem as if it were yearly re-produced in certain earths properly exposed to the influence of the atmo sphere. Bowles's Spain, p. 79. Natron, or the mineral alkali, frequently occurs in the mineral kingdom, not only united with the vitriolic, marine and boracic acids, but even in the more feeble combination into b 3 which which it enters with fixed air. It appears to be deposited in large masse's in various countries, under the surface of the earth, frem which it is extracted by running waters. Thus it is found after the exhalation of ihe vialer, mixed with sand in the bottom of lakes in Hungary, aud in the neighbourhood of Bilin, in Bohemia; it is found at first crystallized, and afterwards withered, on lands recently overflown by that river.

It occurs also in China, where it is called Kien, and rear Tripoli, where it is called Trona; also in Syria, Ægypt, Persia, and India. Mr. Morell lately discovered it in Switzer land, associated with Glauber's salt. It is sel dom, perhaps never, absolutely free from a mixture of common salt. It frequently oozes out of walls, and crystallizes on their surface, mixed with calcareous particles, and is then called Aphronitron. In its decomposed state it presents thin flakes, or a rough dusty powder, of a smoke or yellowish grey colour, tasting alkaline, and easily dissolving in water. It often accompanies beds of lava. It is separated from Glauber's salt, in perfectly by crystallization, more perfectly by saturating it with distilled vinegar, crystal lizirg, aid treating the crystals with spirit of wine.

This will take up the acetous salt, and leave tie Glauber untouched, or by treating the acetated solution w ith acetated barytes, and heath g the precipitate to redness, and weigh ii g it when cold. Its weight will indicate the quantity of vitriolic acid, and the quantity of this acid w ill indicate that of the Glauber's salt, as 1(8 grains of Laic?elcnite contain as much acid as 1C0 grains of Glauber's salt dried in a strong red heat, or as 238 grains of crystallized Glauber. VOLALKALI. Glauber. It is separat edfrom common salt, by treating the nitrated solution with that of ni trated silver; 235 grains of muriated silver indicate the presence of 100 grains of common salt. It is also separable by crystallization, but less perfectly. To distinguish the vegetable from the mi neral alkali, when in a very Small quantity, let the acid of sugar be dropped into the solution, with the former it will form a very soluble salt, with the latter a difficultly soluble, and thence apparent.

If both be mixed, they may be se parated by this means. Volalkali. As pure volalkali consists of mephitic (otherwise called azotic, and formerly phlogisticated ) air and inflammable air concreted together, in the proportion of nearly four parts of the former and one of the latter, particularly when the latter is in a nascent state, and slowly disengaged, (an accident that must frequently happen in the mineral kingdom), it should seem surprising that volalkali should not be often formed, though from its volatility and solubility, it may seldom be detected. Ac^ cordinglv, it has been found in some mineral waters by Mr. Malouin, Mem. Paris, 1746, and by Mr. Cavendish, Philos. Transactions, 1767. 2 Bergman, Erde Kugel, 304, also in beds of coal, in clays, marls, and in various stones, by Henckel, Hiaerne, and others. b 4 CHAP. CHAP. III.

NEUTRAL SALTS. Under this name I comprehend those salts that have an alkali, earth, or metallic substance for their basis. Species I. — Tartar Vitriolalc. — I do not re collect that this salt has been found in the mi neral kingdom free from all suspicion of vegetable origin, except by Mr. Bowles, in certain parts of Spain, Bowles, p. 68, 32. Roz. Jour p 246. Its colour is greyish white, its crystals transparent, their forms various, according to the mode of its crystallization. When its solution is sufficiently dilute and slowly eva porated, hexahædral pyramids, or short hexangular prisms, terminated by one or more hexan gular pyramids ; by spontaneous evaporation it often gives dodccahædral crystals, by rapid evaporation, shapeless masses. It has a bitter taste, its specific gravity is 2,298, Brisson.

In the temperature of 60", it is soluble in 16 times its weight of w ater, but in a boiling heat requires no more than five. It does not effervesce with acids, on burning coals it decrepitates, and scarce loses any of its weight, but diffi cultly melts. One hundred parts of it contain 45 of real acid, and 55 of alkali*. Its solution precipitates those of barytes, strcnthian, silver, quicksilver, or lead, in the * By real acid, I mean the strongest that can exist. See the Transactions of the Royal Irish Academy, vol. 5. nitrous Glauber's salt. nitrous acid, but does not disturb that of alum ; effects which sufficiently distinguish its acid. Neither is it affected by any alkali, pure or aerated, but the acid of tartar slightly precipitates it ; effects which indicate its basis. It frequently retains an excess of acid, and hence reddens litmus, &c. Species 2. — Glauber's Salt. — This salt ex ists in vast quantities under the surface of the earth, in various countries, particularly in the neighbourhood of Astracan, where, in summer, it is found at the bottom of lakes *, and also in Bohemia and Switzerland, where it is deposited by water, in the spring season.

It is never found pure, but mixed with natron or common salt, or Epsom, or selenite. It also, not unfre quently germinates from, and adheres to, the walls of recent buildings. Of that found near Sedlitz, Mr. Reuss gives the following de scription. Its colour is white, inclining to yellow ; its lustre, when fresh dug, 3. its form either that of slender crystals diverging from a common center, or flatted, compressed and hexangular, of from half an inch to two inches long. Trans parent or at least semi-transparent, and of a cool, exceeding bitter taste. These however, soon wither into a dull, dusty powder, its frac ture, when crystallized is the minute con choidal. By a very skilful analysis he found 100 parts of this impure compound to contain 66,04 of Glauber's salt, 31,35 of Epsom, 0,42 of sele nite, and 2,19 of salited magnesias. * 2 Decouvertes Russes, 185. f 2 Chym.

Ajid. 1791, 18. To To the above description we may add, that this salt effloresces by exposure to dry warm air, and if dried in a strong sand heat, loses 58 per cent, of its weight. When crystallized, it is soluble in 2,85 times its weight of water of the temperature of 60° or 0,8 of boiling water. It is subject to take up an excess of acid. One hundred parts crystallized Glauber con tain 22 of real acid, 17 of alkali, and 58 of wa ter of crystallization, and 3 of water of com position. Species 3. Vitriolic Ammoniac. This salt is found in the neighbourhood of volcanos, though not so commonly as might be imagined*, probably because its acid, while as yet imperfect and sulphureous, is expelled by the marine. It has also been found in some lakes in Tuscany, and at the bottom of a burning well in Dauphihe, and on the surface of the earth near Turin f. It is generally impure, being mixed with sulphur, argill, alum, or vitriol of iron.

Hence its colour is grey, yellowish grey, or lemon yellow. It is found stalactitic, or investing lavas, or in an earthy state, with little or no lustre, sometimes semi-transparent. Its fracture uneven. When pure, this salt, by slow evaporation, furnishes white transparent crystals, in the form of slender hexangular or quadrangular prisms, but if the evapora tion be more rapid, only scales. Its taste is sharp and bitterish; it slowly at tracts moisture from the air; it is apt to take up an excess of acid. In the temperature of * Dolomieu on 3 Bergman. 1st Table. t 16 Roz. Jour, p, 363. 6 Roz. Jour. p. 125, ke. 60° it EPSOM SALT. 60° it requires twice its weight of water to dissolve it, but its own weight of water at 212° is sufficient. When heated, it at first slightly decrepitates, then liquefies, and in close vessels sublimes, but with some loss of its alkali.

With nitre heated to redness it gently deflagrates. One hundred parts crystallized vitriolic am moniac contain 29,7 of mere alkali, 55,7 of real acd, and 14,16 of water. Its acid is discovered by the tests already mentioned, its basis by mixing it with quicklime or caustic fixed alkalis. Species 4. — Epsom Salt. — The province of Andalusia, in Spain, contains this salt in the greatest abundance, insomuch that after heavy rains, the surface of the earth appears grey from the quantity of this salt that germinates upon it. It is found rjso at the bottom of desiccated lakes, on grit stones, and argillites*. Next to Spain, Bohemia perhaps contains most of it, it is there found in acicular grey crystals, or in a more compact form, mixed with reddish clay, selenite, and an excess of acid; and in se veral mineral springs.

Dr. Armet found it in the gypsum quarries of Montemartre, near Paris. And frequently it is seen efflorescing on argillites. It is also contained in some mineral waters in most countries, particularly in that of Epsom, and Saidschutz in Bohemia. It often germinates from walls. It is often mixed with a large proportion of Glauber's salt. When pure, it presents quadrangular prisms, * 32 Roz. p. 247. whose whose planes are equal, surmounted with quadrangular pyramids, or acicular crystals. Its taste is very bitter. It effloresces by exposure to the air, it is soluble in its own weight of water at the temperatu re of 60° or in three -fourths of its weight of boiling water. In a strong sand heat it loses half its weight by the loss of its water of crystallization, and foams. One hundred parts of it contain 17 of mag nesia, 33 of standard vitriolic acid, ( =29, 46 real acid) and 50 of water of crystallization.

Its acid is distinguishable by the tests al ready mentioned, its earth is in some measure precipitable by caustic volalkali, when dried and aerated it does not harden, it is easily so luble in dilute vitriolic acid, which sufficiently discriminates it from argill, which volalkali can also precipitate, but which dilute vitriolic acid slowly and difficultly dissolves. Species .5. — Alum. — It is found native in five states. 1st, Invisibly dispersed through a marshy black soil, unaccompanied with any other salt, as in Arragon, near Alcagniz. Bowles, p. 388, and 389. Or dispersed through sand, and ac companied with other vitriolic salts, as in Hun gary, at the bottom of some lakes. 1 Chym. Ann. 1793, p. 528. Or 2nd, in a. white or brownish white, or grey, or yellowish grey crustaceous form investing lavas, in the neighbourhood of volcanos, and some rocks in the Archipelago, and in coal mines; or in grey flakes, or crystalline grains, in some aluminous slates, or in the form of a yellow powder, of an astringent taste, which blackens when exposed to flame. 5 Bergm. p. 122; Or 3d, in tender ALUM der capillary silvery white crystals, inclining to green, of a sweetish astringent taste, called ca pillary alum, haarsalze of the Germans, halo trichium, or trichites of others, found in Italy, Sicily, Hungary, &c. When contaminated with calx of iron, these crystals are more or less tinged with yellow.

Sometimes these crys tals are closely interwoven with each other, and dentiform. Or, 4th, in soft brittle masses, that feel somewhat greasy, and thence called by the Germans stone-butler, of a dark yellowish colour, foliated fracture, and sweetish astringent taste. This substance contains decomposed vitriol of iron as well as alum; at first it is perfectly soft, but by exposure to the air, be comes brittle. It is found in Siberia and Sax ony, &£. 5th, dissolved in a few mineral waters, as in the vicinity of Halle in Germany. 1 Chym. Ann. 1788, p. 224. Mem. Paris 97. 1777. These seem to have carried it into fossil wood, which is often found penetrated with it. Lastly, it is found crystallized (we are not in formed how) in the caverns of Segario in Sar dinia. Mem. Tur. 1788. p. 160. ad fin. Alum, when pure and properly crystallized, shoots into transparent octahædral crystals, formed of two quadrangular pyramids, united base to base, of a sweetish astringent taste.

They slightly effloresce by exposure to the air, require in the temperature of 60° to dissolve them quickly, 34 times their weight of water, but half that weight wiill dissolve them in some days; of boiling water they require rather less than their own weight. Exposed to a strong heat they sublime, swell, foam, and at last lose 44 per cent, of their weight. The solution al ways reddens, litmus, &c. One One hundred parts of alum contain 19,78 of standard acid ( = 17,62 real, acid) 18 of earth dried in a high red heat, and 44 of water of crystallization, the remainder water of composition. Its acid is discoverable as in the foregoing salts; its basis by its precipitancy not only by caustic volalkali, but also by pure magnesia, and the difficult solubility of the dry precipi tate in acids Species 6. — Aluminous Ores. — By alumi nous ores, I mean those substances in which alum does not originally exist in a native state, but in which it is formed by subsequent opera tions of nature, or of art.