M. MEDICUS is of opinion that mushrooms are produced, by means of moisture and heat, from the condenfed juices of vegetables, in the firft ftage of their decomposition; for those which are actually become putrid are unfit for this process of nature, which our author calls vegetable cryftalization. He thinks that mushrooms may thus be produced, not only from any vegetable, but alfo from animal fubftances; and he maintains that the mouldinefs, which is collected on meat, that has been dreffed and kept in a damp place, is nothing more than a kind of mushroom. We fhall not detain the reader with the unphilofophical reafoning adduced in fupport of this hypothefis of equivocal generation, which, in this enlightened age will not find many advocates.

MINERALOGY.

Obfervations tending to prove that all the Arenaceous part of Switzerland, and the Plains of the Circle of Bavaria, owe their Origin to Lakes of fresh Water. By Count RAZOUMOWSKI.

In a work, entitled The Natural History of Forat and the adjacent Countries, published by the author of this memoir, he had expreffed his opinion that all the great lakes of Switzerland once formed one vaft mass of water, out of which the fummit of the present mountains then rose as fo many iflands. The article before us contains the obfervations that occurred to him during a journey, which he took with a view to examine whether the appearance and ftrata of this country were such as to confirm his hypothefis. These particulars are here very minutely described but, as they would not be very interefting to our readers, we fhall only inform them, that the Count confiders his theory as fo fully confirmed, that he proceeds to afcertain the extent and boundaries of his fuppofed lake; of which he says the greatest length, from fouth-west to north-east, must have been fifty-nine leagues, and the greatest breadth, twenty-three; he imagines, that it was bounded on the fouth by the mountains of Upper Faucigny near the lake of Geneva, on the north-eaft by the mountains of Suabia, on the weft by mount Jura, and on the eaft by the calcareous mountains of the diftrict of Aigle.

He alfo thinks that the plains of Suabia and Bavaria, comprized between the northern banks of the lake of Conftance and the Danube, once formed a great bason of fresh water, which communicated with that of Switzerland.

On the Natural Hiftory of the Circle of Bavaria. By the Same. This memoir is written with a view to fupport the hypothefis advanced in the former: but to those who have not a very strong predilection for geological conjectures, it will appear dry and uninterefting. The Count fuppofes that the great

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lake of Bavaria was bounded by two vaft chains of mountains of granite. One of these is a continuation of the mountains of Bohemia, extending, from the south-eaft to the north-weft, from the banks of the Danube near Paffau, to the mountains of Alface; the other runs from the south-weft to the north-east, and is terminated on the north by the Fichtelberg.

On the Salt works in the Circle of Bavaria. By the Same. The works here defcribed are thefe of Hallein, in the principality of Saltzburg, of Bergtolfgaden, of Reichenhail and Trauenftein in the dutchy of Bavaria. At Hallein and Bergtoligaden, the falt is found in its fofile ftate; in order to obtain it, large cavities, called chambers, are dug in the mines, and filled with fresh water; fome of thefe are fo large, that the water must stand in them during two years, before it is fufficiently impregnated with falt; in others, this process does not require more than a few weeks; when the water is faturated, it is carried through the mountain by pipes into a refervoir, whence it is conveyed to the cauldrons: of thefe, there are four at Hallein, and two at Bergtolfgaden, which are not above four leagues diftant from each other: the salt annually made, at the former of these places, amounts to four hundred thousand quintals, and, at the latter, to one hundred and fixty thousand.

The fprings of Reichenhall are about four leagues from Bergtolfgaden, and are fuppofed to be impregnated with the falt of this mountain: they are twenty in number, but falt is made from only four of them: part of the water proceeding from them is conveyed by pipes to the cauldrons at Trauenftein, which is about three leagues diftant. The falt annually made from thefe fprings amounts to two hundred and fifty thousand quintals.

The Count fuppofes that the mines at Hallein and Bergtolfgaden are parts of the fame bank of falt, which he thinks is a continuation of that at Gmund in Auftria, about eight leagues from Hallein; the irregularity of the ftrata feems to indicate that the connection, between the two mines here defcribed, must have been broken by fome violent revolution.

Concerning Coal. By the Same.

The Count diftinguishes this foffil into animal and vegetable; the former confifting of aquatic animals, the latter, of vegetable fubftances, converted into bitumen. These two claffes are difcriminated by the colour and quality of the afh; that of the animal coal is white, whereas that of the vegetable is red; the former will effervefce with acids, but the latter will not. He acknowleges, however, that this divifion is not well fuited to a fyftem of mineralogy; and he obferves, that in this view, it will be more convenient to attend to external cha

racters,

1

racters, by which coal may be diftinguished into four fpecies. Thefe are, lithantrax Gagas, piceus, fchiflofus, and terreus: the first of thefe is what is generally called Welch coal, and is very feldom found on the continent,

Memoir on Foil Wood. By the Same.

The Count here defcribes nine fpecies of foffil wood found in Switzerland, most of which have been mentioned by Wallerius, in his Syftem of Mineralogy.

Defcription of a new Species of Stone. By the Same.

This tone is found at Rauwenftein in the Upper Palatinate, where it forms a bed forty feet and a half in depth, in which it lies in ftrata, each about two inches thick, and feparated from that beneath it by a ftratum, two feet deep, of white mica, unmixed with quartzous particles. It has hitherto been confidered as a red quartz: but this academician maintains, that it is a ftone fui generis, to which he gives the name of fapphirine jpar. It is perfectly tranfparent, and of a changeable colour, which varies according to its pofition with refpect to the light when this is reflected perpendicularly from its furface, it appears of a pale red: but, if placed on a dark foil, er feen in an oblique direction, it exhibits a fine blue. It is fo hard as to cut glafs; and the Count confiders it as a gem which ought to be claffed between the emerald and the oriental chryfolite.

On the Formation of Granite. By the Same.

The Count is of opinion that granite is formed by chrystalJization, in order to which there must have been a previous folution of its fubftance in fome aqueous fluid. This fluid, he contends, could not be of the fame kind with that in which calcareous and argillaceous mountains were produced; for then the refults of the procefs would not have been diffimilar. Befide, neither fresh nor falt water is capable of perfectly diffolving quartzous earth. He therefore thinks it neceffary to fuppose a chemical agent poffefling this property; fuch is the Auoric acid; hence he imagines that the earth was once covered with a vaft ocean of this acid; that in it the vast quantity of quartz, of which our prefent mountains of granite were formed, was entirely diffolved; and that in confequence of the evaporation and concentration of this fluid, the cryftallization. took place, to which he afcribes the production of the rocks. On this bold hypothefis we fhall leave our readers to make their own remarks,

Account of the Baths of Louëch. By Dr. LEVADE.

Thefe baths are fituated in a deep valley, furrounded on the caft, weft, and north, by mountains; hence the temperature

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of the air is remarkably mild, and the foil fertile: the Dala, which flows from the neighbouring glaciers, winds through the valley, and runs into the Rhone near Louëch.

The heat of the principal spring is estimated equal to fortythree degrees of Réaumur's thermometer. The baths are emptied, cleaned, and filled again every evening, that the water may cool during the night, and be ready for the bathers in the morning its temperature is thus reduced to about twentyeight degrees.

Thefe waters have no peculiar flavour either of fulphur or fixed air; and, notwithstanding their great heat, do not boil fooner on the fire than those of the coldeft fpring. The Doctor gives no chemical analyfis, but fays, that they abound with crocus martis; and he recommends the internal and external use of them in all those cases in which warm mineral baths are usually prescribed.

Memoir concerning M. Born's Method of amalgamating Gold and Silver Ores. By Profeffor STRUVE.

In the year 1786, M. Born published at Vienna an account of his method of feparating gold and filver from the ore by amalgamation. Profeffor STRUVE bere gives a short description of the procefs, and examines the principles on which its advantages are founded.

The difference between M. Born's method, and the common one, confifts in his directing the ore, after being washed and ground into a very fine powder, to be mixed with common falt, and roafted in a reverberating furnace. The Profeffor obferves that, by roafting the ore with falt, a double decompofition takes place, in confequence of which the vitriolic acid unites with the alkali of the falt, and the muriatic acid, combined with the metals, forms metallic falts. Hence more foluble falts are obtained, the vitriolic falts and acids are prevented from corroding the furface of the mercury, and the muriatic acid, being rendered elaftic, acts on the imperfect metals with greater efficacy, and calcines them with more ease. He thinks that to this agency of the muriatic acid, the principal advantage of M. Barn's method may be afcribed: but he is of opinion that the procefs might be improved, by roafting the ore before the falt is added, and afterward triturating it with about a fixteenth part of falt and water.

The proportion of falt, which, according to M. Born, ought to be mixed with the ore, previously to the roasting, is about eight pounds to the hundred. The amalgamation is per

* See an account of a tranflation of this work, in the M. R. for June laft, New Series, vol. viii. p. 174.

formed

formed in copper veffels, over a gentle fire, by which the metal is heated to between fifty and fixty degrees of Réaumur's thermometer.

CHEMISTRY.

Analysis of the Waters of Amphion. By M. TINGRY.

The cold mineral fprings, here mentioned, are near Evian, on the fouthern banks of the lake of Geneva: the water contains calcareous earth, fixed air, and iron; the latter is fufpended but not diffolved in it.

AGRICULTURE.

Memoir on the proper Seafon for pruning Vines. By the Abbé

BERTHOLON.

After fome observations on the advantages refulting from this operation, the academician inquires whether the spring or the autumn be the most proper feafon for performing it. If the climate be warm, and the vineyard fituated in a dry air and foil, he prefers the autumn: but, if the climate be cold, the foil damp, and the vines expofed to moift rainy weather, he thinks they may be pruned with greater fafety in the spring. However, in the latter cafe, he advises to prune both in autumn and spring; in the firft pruning, to leave the shoots about double the ufual length, and to cut them off closer in the following spring. Thus all the advantages of autumnal pruning will be gained, and the danger avoided.

Defcription of a new Kind of Bee-hive. By M. DE GELIEU. This hive appears to be a fimple and ingenious contrivance, for which we are originally indebted to the inhabitants of Madagafcar. It may be conftructed of either ftraw or wood: but, as its internal dimenfions must be the fame throughout its whole length, it is neceflary that its form fhould be either cylindrical or prifmatic. Its principal advantage is, that its bases are moveable, and may be fixed by pins at any diftance from each other; by which means, its fize may be increased or diminifhed at pleasure. It must lie on its fide; and, in the foremost bafe, must be a paffage for the bees. Hence, by drawing out the pofterior bafe, the honey may be taken out of the back part of the hive, without hurting the bees; and, when this is done, the bafe fhould be puthed in clofe to the remaining comb, in order to avoid leaving any intermediate space. Another advantage is, that, by turning the hive, and making the entrance in that which had before been the pofterior base, the bees will build new cells, in the room of what had been taken away; in confequence of which, the honey will be more pure and white.

From