nular eurite, and which alternates with the eurite. The eurite is accompanied in the Erzgebirge by subordinate blocks of ophiolite or serpentine. It does not shoot out in filons. The gneiss lays on it conformably. It is is surrounded by mica-schist and phyllade, which rest on it also conformably. Eurite loses part of its feldspar, and then contains quartz; it passes into mica-schist. Eurite is of age next to granite. 3. Gneiss. It rests either on granite or eurite. It passes into micaschist or phyllade, and its youngest portion sometimes alternates with these, appearing in them in thin beds (bancs). It contains as subordinate rocks, beds (bancs) of porphyry, amphibolite, quartz, primitive limestone, and pyrites. It contains many thin metallic strings, of the ores of silver, copper, lead, cobalt, bismuth, antimony, arsenic, &c. It encloses a transverse mass (stehenderstock) of granite, con taining tin. Two warm springs were observed in the gneiss near amethyst. 4. Mica-schist (glimmersheiffer) rest conformably on the gneiss; sometimes on the eurite or on the granite, where with its lower strata sometimes alternate. Encloses as subordinate rocks, beds (bancs) of serpentine, schistose diabase (grunstein scheiffer hornblende schist?) and limestone, talc steatite, oxydulated iron, pyrites and blende. 5. Hyalomicte (graisen or greiss) forms mountains at Zinnwald: encloses blocks of granite, and stanniferous quartz. 6. Oñhiolite: serpentine. Two formations; one in beds stratified on eurite, alternately therewith and with the mica-schist: the other forming a powerful and extensive mass, not distinctly stratified, reposing unconformably on gneiss.

Both contain asbest and oxydulated iron. 7. Phyllades and schists. Several formations, a Primitive schist," follows gneiss and micaschist. conformably. They enclose ampelite, jasper-slate, amphibolite leptinite. Sometimes pass into psammite (grauwacke, killas). They also enclose as subordinate rocks, blocks of porphyry, quartz, granite, syenite, gneiss, granular diabase, schis: tose diabase, calcair; also ores of copper, lead, and iron. These ores are more abundant in the passage of primitive phyllade into micaschist, schistose amphibolite (hornblende slate) or slaty jasper. In this case, the rock contains wacke. b. Transition phyllade: lies on the primitive conformably. It is difficult to determine the limits. It is distinguished principally by its alternating with psammite, (grauwacke,) of which, and of calcair, (primitive limestone.) it contains beds (bancs). In the Hartz, organic remains are found in the slates generally called primitive by the German mineralogists. It is also to be observed, that conformity of stratification is one of the principal characters of rocks of the same class This character belongs to the primitive and what are called the transition phyllades: hence it is doubtful whether there be sufficient foundation to divide them into primitive and transition. The last species of phyllades, contain blocks of diabase, schistose jasper, and schistose granular quartz. If we follow the schists into the newer formations, we shall find the slate clay, often called clayslate, (scheifferthon,) alternating

- Primitive slate or schist has been

found, as is said, to contain vegetable impressions, hence it is a phyllade. T.

with micaceous psammite or sandstone of the coal formation in Zwickau and other places. 8. Syenite This is found in blocks subordinate to the primitive phyllades, in unstratified masses, much like the third-described granite of which it is a suite, and seems with it to constitute one formation. Syenite is various in the proportion of its constituents, and sometimes puts on the character of granite. It is accompanied by beds (bancs) of porphyry, gneiss, amphibolite, calcair, strings or veins of diabase, basaltic hornstone, and metallic veins. 9. Pyrites. This mineral occurs in such abundance in the Erzgebirge, as, to merit separate consideration. It forms beds in the gneiss and mica-schist. These pyrites are of iron, copper, arsenic,

zinc: sometimes oxydulated iron,

with ores of copper and lead, unite

in the limestone which forms a

gangere for all these minerals. 10, Amfishibolite, micaceous and schistoid. (Hornblendgestein, hornblendscheiffer). In subordinate beds in gneiss, mica-schist, and primitive phyllade, which often pass into this rock. 11. Schistose Jassier (keisel scheiffer, leidischerstein) lapis lydius? This is met with in primitive phyllades, in psammites and transition phyllades. 12. Quartz. In beds, in gneiss mica-schist, and primitive and transition schist. In strings or veins in almost all the older rocks. Generally found in beds on the surface of mountains. 13. Porfihyries. a. In beds in gneiss. b. In primitive phyllade, c. covering gneiss unconformably (abweichende Úbergreiffende lagenung.) d. Sienitic porphyry, e. Reposing on gneiss and containing anthracite. f. Newer porphyry, pro

[ocr errors]

bably belonging to the old red sandstone formation (gres rouge, fodte liegende). When the paste becomes coarse they pass into clay porphyry, and argillolite (thonstein). Sometimes they contain rolled fragments of agate, jasper, gneiss, &c. In Germany the miners generally suppose porphyry accompanies coal. In Saxony and Silesia it reposes on the coal Stl’ata. 14. Calcair. Primitive limestone. In beds in gneiss, in mica-schist, in primitive phyllade, in syenite. It is sometimes compact, sometimes granular, sometimes saccharoid, often accompanied by mica, talc, amphibole, pyrites, quartz, diabase, &c. When these are in blocks they contain iron and other ores worth working. It is also found in transition formations. Here it often contains sparry veins, which seem to have been organic matter destroyed and supplied by chrystalline infiltration. (?) 15. Traffi. a. Schistose diabase

[blocks in formation]

16. Psammites and Sandstones. a. Fine grained Psammite (feincornige grauwacke) and psammitic phyllade (grauwacken scheiffer) in the primitive phyllades which are sometimes found under our third granite. b. Quartz psammite (grauwacke) of all sized grains passing into grauwacke schist (scheiffrige grauwacke), sometimes into argillaceous pudding stones in extensive strata covering conformably primitive country. It includes transition schists, jasper schists and calcair. In the Erzgebirge this is not traversed by any metallic vein, while in the Hartz, and other countries, metallic veins abound in it. c. Micaceous Psammite or sandstone of the coal formation, alternating with slate clay and coal, covering either concavely, common porphyry, or the transition country conformably, so that the formations extend from the mica-schist to the coal. (Terrain houiller.) d. The red psammites, the psephites, the psammitic pudding stones, I consider as belonging to what is called the (old) red sandstone formation, whose relation to the coal formation is not accurately determined. e. White sandstone (quadersandstein) containing fossil shells. f. The sandstone in the neighbourhood of Carlsbad. This covers (not the coal like the quadersandstein) but the lignite of Carlsbad.

17. Coal Formations. Combustible carbons, steinkohle. a. Anthracite. Scheiffrige Glanzkohle, in beds in the porphyry over the gneiss. b. Coal of the principal formation, scheifferkohle, pechkohle: sometimes covering porphyry concavely, and sometimes covering transition strata conformably. Sometimes in contact with the red sandstone, and sometimes with variolite or mandelstein. c.

The coal of the white sandstone. d. The brown coal, lignite is not found in the Erzebirge. The preceding memoir I consider so interesting as to induce me to give this long account of it. M. Menard de la Groye, in a memoir on the geognostic appearances at Beaulieu in the department of the mouths of the Rhone, has entered into a comparison between the second ry trapps, basalts and volcanic products, and concludes that the secondary trapps are of two kinds, the soft and the hard, (doux et aigres). That the former may be of neptunian, the latter of submarine volcanic origin, in this manner. When the lava was first formed, the basalt with peridot, forming the summit of this district was formed exposed to the air only, while the rest of the lava spreading over a soil covered with water formed what the Germans call the floetz trap; and that a complete passage can be observed between the grunstein and the basalt. The supposed floetz trap of Beaulieu, like the undoubted volcanic strata contains, peridot, titanium, idocrase, pyroxene, obsidian, and the balls in concentric layers, frequently found in volcanic soil. Primitive trap contains none of these,being composed of amphibole and feldspar in confused mixture. This memoir, published in the Journ. de Phys. for February and March, 1816, has been contested by J. Andrè de Luc, in Journ. de Phys. for May. M. de Luc contends that the pyroxenes, the leucites, the oxydule of iron containing titanium in the ferrugineous sand of volcanoes, have been ejected in the state in which we see them and not formed in the lava which surrounds these substances. That this has been frequently the case

with Ætna and Vesuvius, and that the leucotes that almost cover the road between Rome and Frescati, have been ejected from the extinct volcano of Monte Cavo or Monte Albano. But the most important essay on this subject is that of M. P. Louis Cordier, of which La Metherie has given Brogniart's analysis, in the Journ. de Phys. for April, 1816. Cordier, took volcanic stones (laves hithoides) and by strong pressure (not trituration) he broke them down into pieces of from +}t; to go of a millemetre in size. He washed away the dust, dried the subsiding particles, and examined them with a microscope. The general result was, that volcanic rocks presented particles of various appearances, white, bottle green, brown and reddish brown. The white grains, were either referable to feldspar, peridot, or amphigene. The yellowish, greenish, or blackish green grains, he refers to amphibole. The opake black grains are titaniferous iron, magnetic. 2. The volcanic stones that melt into a black glass, contain chiefly pyroxene, sometimes as much as 45 per cent. 3. The principal component parts of these rocks, are pyroxene and feldspar. The latter melts into a white glass or enamel. Hence he divides volcanic stones into Ieucosthenes that afford a white glass or enamel, and basalts that afford a black glass. 4. Basaltic rocks treated like volcanic rocks offer the same appearances exactly to the microscope, and by the usual tests and analyses. 5. This mode of examining rocks, presents marked difference between primitive and basaltic or

secondary traps, whlch the Wernerians refer to neptunian, the French and Italian mineralogists for the most part to volcanic origin. Primitive traps, petrosilex and hornstone, frequently enclose and are mixed with diallage, serpentine, talc, chlorite oxydulated, and sulfuretted iron: volcanic rocks, never. These last enclose and are mixed with, peridot, amphigene, pyroxene, titaniferous iron; substances which the first named rocks never present. or * 6. Whether the volcanic rock be antient or modern, vitreous in appearance or stony, bruised and viewed with a microscope, it always presents similar substances, consisting chiefly of pyroxene, feldspar, peridot and titaniferous iron: (frequently also leucite or amphigene.) Hence there is no analogy between primitive and basaltic traps. (On this it may be observed that pyroxene, amphibole, and diallage scarcely differ in chemical analysis except as to a little more or less of magnesia; diallage seems to be hornblende with chrome: its geologic situation, being in the immediate neighbourhood of chromated iron.) Dr. Thomson’s account of the basalt over the coal at Dudley, containing augit or hornblende, seems to confirm Cordier’s account, Ann. of Ph. Sept. 18 6. M. Cordier in the Journ. de Phys. for May, 1816, has also given an account of the salt mountain at Cordonna in Catalonia, 16 leagues from Barcelona. It is about 100 metres high, but a third larger at the base than Montmartre. It is washed at its base by the Cordonnero. There is no vegetation upon it. The minerals it contains, are coarse grained white and coloured

[ocr errors]

common salt, grey clay, common and anhydrous gypsum. The common salt consists of on of the whole mass. Impure salt mixt with argillaceous matter so, gypsum and pure common salt about * . There is no regularity in the form of the masses, in their position, or stratification. The mountain rests upon grey and red micaceous sandstone, argillaceous shist, and grey limestone, not bituminous, and containing few or no organic remains. In the opinion of the inhabitants of the neighbourhood the mountain has suffered no diminution, but that can hardly be the case, as the salt is soluble. Upon the whole, appearances indicate that the rock is based on transition strata, (intermediaires) covered by secondary layers, and that we must allow of a transition gyps and rock salt formation. Mr. Mornley has found a block of meteoric iron, near the bank of a river, about 50 leagues from Bahia in the Brazils, in a barren granitic country. It measures six feet by four feet, contains about 28 cubic feet, weight about 14,000 lbs. A specimen sent to Dr. Wollaston was found to contain nichel. M. Beudant has found that the moluscae of salt and of river water may be gradually accustomed to live within the one or the other. This will account in some degree for the mixture of marine and fresh water shells in the same rock.


M. Buchholz, in the German Pharmaceutical Almanack, has noticed the property of honey to pro mote the solution of borax; equal parts of honey and borax form a substance like gum arabic soluble in three waters. It greens the syrup

of violets and browns turmeric; muriatic acid decomposes it, alcohol has little action on it. In a memoir on the combinations of azot with oxygen, whereof Daltz admits 3 acids and Davy two, we find Oxyd of azot, 100 volumes azot with 60 oxygen. Nitrous gas, 100 - - - 100 Pernitrous acid, 100 - Nitrous acid, 100 - - Nitric acid, 100 - M. J. F. John has found a peculiar acid in stick lac. Gay Lusac has found that sulphuric ether, kept for two years in a bottle with a glass stopper, half filled and occasionally opened, is converted into acetic acid, alcohol, and a peculiar oil which is not the oil of wine, M. Planche had made nearly the same observations. The memoir on a new classification of simple bodies, by M. Ampere, seems to add to our knowledge nothing but names, where with we are overwhelmed already. R. Dulong has distinguished four distinct acids formed by phosphorus and oxygen. M. Theodore de Saussure from experiments on the atmosphere, calculates the proportion of carbonic acid in winter at 4.79 parts, in volume in 10,000 parts; or 7,28 parts in weight. In summer the proportions were 7, 13 parts in 10,000 by volume, and 10,83 by weight. The experiments were made in the open air, near the lake, a league from Geneva. Journal de Pharmacie. M. Kirchoff who published the method of converting starch into sugar by means of dilute sulphuric acid, has made experiments on the conversion of starch into sugar by means of gluten. He concludes that sugar is formed in grains during germination by means of

450 200 250

« ForrigeFortsett »