dental disease of the plant, occafioned by the heat of the fun, or the dryness of the atmosphere. He thinks, that if moffes are propagated by feed, this is contained in the capfules, ant needs not the concurrence of the fexes in order to its fecundation.

MINERALOGY.

Analytical Experiments on the Goumoën Stone. DE RAZOUMOWSKI.

By the Count

This ftone is fo called, from the name of the place where it is found it appears to be a kind of calcareous marle, impregnated with bitumen, which, when diffolved in the vitriolic acid, yields a fulphureous fmell.

Account of a Polished Cupreous Rock, found on Mount St. Bersard. By the Same.

This mountain feparates Piedmont from Vallais: the rock here deforibed is near its fummit, twelve hundred toifes above the level of the fea, and forms a very confiderable projection, which rifes perpendicularly like a wall that part of it which fronts the fouth- weft, and is exposed to the winds and rains from this quarter, has a furface as smooth as if it had been polifhed by art. It is an opaque quartz, with white spots on a black ground, which are afcribed to a combination of the quartz with a cupreous bituminous fteatite, of a fhining black colour, which is greafy to the touch, and ftains the fingers: in this the Count fuppofes the copper to be diffeminated, in the form of calx. From an hundred weight of this ftone, nearly twenty-five pounds of copper were obtained.

CHEMISTRY.

Obfervations on the Analyfis of Sedative Salt, and the Compofition of Borax. By M. H. ExCHAQUET, and Profeffor

STRUVE.

It is well known that borax confifts of a mineral alcali, and of a fedative falt: but concerning the analysis of the latter, nothing certain has hitherto been discovered. Thefe authors were led, by a confideration of its properties, to fuppofe that the phofphoric acid was one of its conftituent principles; and thought that, by increafing the proportion of this, which they confidered as the folvent part, the decompofition of the falt might be effected: with this view, they diftilled a mixture of two parts of phosphoric acid, evaporated to the confiftence of honey, with one part of fedative falt, and two of water; bence they obtained an oleaginous acid, which had all the properties of the phosphoric, and the refiduum was a confiderable proportion of white vitrifiable earth. It appeared extraordi

PP 4

nary

nary that the phofphoric acid, which is naturally fixed, should become volatile; and Meff. E. and S. attempt to explain this circumftance, by obferving, that it is fixed when combined with phlogiston, and volatile when united with the principle of fire, (matiere du feu): they conclude, therefore, that the fedative falt is compofed of vitrifiable earth, phosphoric acid, and the principle of fire. In order to illuftrate this diftinction between phlogifton and fixed fire, which, they tell us, is founded on the mode in which the principle of fire is combined with bodies, they obferve, that metals, when calcined, are deprived of their phlogifton, but contain fixed fire, which, not being combined with any particular conftituent part of the metal, must be confidered as a proximate principle. The regulus of arfenic, they fay, illuftrates the exiftence of the principle of fire in both its modifications: this, when deprived of phlogifton, becomes a calx; which, being combined with thofe fubftances, that have an affinity to the principle of fire, will yield what is called the acid of arfenic: if this be exposed to the action of fire, the principle of fire will combine with it, and it will become calx of arfenic; and if, to this calx, an inflammable fubftance be added, the refult will be the regulus. In the prefent divided ftate of opinions concerning the theory of calcination, we fhall offer no obfervation on this hypothefis, but leave its merits to be determined by the opinions of our readers.

In order to confirm this analyfis, the prefent authors have endeavoured to compofe fedative falt, by a combination of the above principles: but hitherto they have not been able to make the principle of fire unite with the other two; and the faits and glafies which they have made, do not poffefs all the diftinguishing characters of the fedative falt, though fome of them resemble it in tafte and form, in the hardnets and folubility of their cryftals, and in the property of giving a green hue to the flame of a piece of paper impregnated with it.

These refults lead the authors to hope, that the compofition of fedative salt and of borax may poffibly be effected; and induce them to recommend the trial of fuch experiments as may promote the discovery. With this view, they give a very particular enumeration of the properties of borax. They advife a combination of the phofphoric acid with alcalies, because they think that thefe contain a large proportion of vitrifiable earth, and of the principle of fire, which they confider as the elements of fedative falt: for the fame reason, they recommend a mixture of the acid of phofphorus with thofe earths which are obtained by the decompofition of alcalies, and with argillaceous earths; and, laftly, they with for experiments on

urine, in which, according to fome chemifts, the fedative falt is found completely formed.

Obfervations on the Method of extracting the Phosphoric Acid from Bones, and on its Utility in the Arts. By the Same.

The authors obferve, that this acid, when obtained by the common process, is feldom pure, and is lefs in quantity than may be extracted from the materials. Their directions are, to digeft twenty ounces of bone, flightly calcined and powdered, in a pound of oil of vitriol fufficiently diluted; to this add the vitriolic acid, guttatim, every now and then shaking the mixture, and afterward letting it fettle; this must be continued till the precipitation ceafes: evaporate this liquor till it is of the confiftence of honey, feparating the felenitic falts, as they appear: if to the liquor thus evaporated, a fufficient quantity of alcohol be added, all the felenitic falts will be precipitated, and leave the phosphoric acid mixed with the alcohol: let this be poured off and evaporated, and the phosphoric acid will be so free from earthy particles, that even when faturated with alcalies, it will fcarcely become turbid. This procefs, the authors obferve, affords a proof that the acid is foluble in fpirits of wine; which fome writers have denied.

The phosphoric acid is here confidered as highly useful in chemistry, for the decompofition of thofe fubftances of which it is a conftituent principle; in this view, it is recommended for analyfing fchorls and precious ftones, which the authors confider as phofphoric compofitions: by means of this acid, moft metals may be changed into an irreducible earth, which, by the addition of a greater quantity, may be made to run into glass. The acid and falts of phofphorus may hence be ferviceable to enamellers, and enter into the compofition of factitious precious ftones: by a combination of the phosphoric glafs with gyps, or with offeous felenites, or with calcareous earth, a glafs may be obtained, as bright and hard as the finest factitious cryftal; it is remarkably ductile, and easily unites with metallic colours: combined with a folution of gold, the phofphoric acid forms a compofition, with which glass may be gilt, without expofing it to more than a flight degree of heat. A new Theory of Saline Springs and Rock Salt. By Profeffor STRUVE.

The Profeffor here proposes to examine the fituation, nature, and local circumftances, of the faline rocks and fprings which are found in various parts of Europe: thence to explain their phenomena, and to deduce fome obfervations relative to the management of the falt-works at Aigle. We fhall endeavour to give the outlines of his memoir: but, as it is very long, we muft

must refer to the work itself for thofe particulars on which our limits will not permit us to dwell.

Rock falt, fays the Profeffor, is found only in mountains of the fecond order, which confift of ftrata, and is never seen but in a bed of argillaceous rock, which is generally covered with a compact calcareous ftone; its fituation is not limited to any particular part of the mountain, though it is feldom difcovered in very elevated places.

Saline fprings are alfo difcovered only in fecondary mountains they rife out of gyps, calcareous stone, and sometimes out of gritstone but they derive their origin from the argillaceous rock, and will rush out of it on piercing the ftratum which covers it: or, if a well be dug in it, the water will rise till its weight is equal to the preffure that it fuftains.

It is obferved that, in the fame faline diftrict, the fprings have a communication with each other: if wells be dug in different parts of an argillaceous ftratum, they will all be filled to the fame level; and, if one of them be emptied, the water in the others will fink till the level is reftored. Hence M. STRUVE concludes that, by digging wells, falt fprings may be found in every part of a faline diftrict: he obferves, that the argillaceous ftratum may be confidered as a kind of bafon, or reservoir, in which the water is comprefled by the weight of that above; so that, whenever an opening is made, it fprings up to a confi derable height: thus, not only the argillaceous rock, but also the water which it contains, must be confidered as ftrata, fubject to the fame laws with those that lie above them.

From the circumftance of the water rifing in the wells, it is evident that it defcends from a more elevated fource: it is always found in a fituation lower than the rock falt; and, in general, the fprings rife in places surrounded with gyps, which forms a kind of bafon for the water: fometimes, indeed, they are difcovered in the vallies, near rivers, in marfhes, and in peat-grounds.

The degree of faltnefs in the water of thefe fprings, depends on their being fecured from a mixture with fresh water: those which rife out of gyps are moft falt; whereas others, which iffue from the calcareous rock, are lefs fo; because this is more pervious to fresh water. The rock falt and the faline fprings are both found in the fame argillaceous ftratum; and the only difference between them feems to be, that, in the latter cafe, it has imbibed water, which, in the former, it has not.

In thefe fecondary mountains, the argillaceous rock, which contains the fal gemmæ, forms a regular ftratum, and does not affume any particular configuration. This ftratum is, in

fome

fome places, impregnated with falt, and, in others, has imbibed water but the whole is confidered as depofited by the ancient ocean, and therefore of confiderable extent. Though called argillaceous, it is not pure clay, but only a substance of which this a principal element, and which is pervious to water, in confequence of its fiffures and vacuities.

With respect to the filtration of the rain and fnow that defcend from the top of the mountain, the Profeffor is of opinion that the water, which follows the course of the gypfine, calcareous, and arenarious ftrata, and is collected in them, remains fresh; whereas that which is imbibed by the argillaceous ftratum, becomes impregnated with as much falt as it can diffolve.

The remainder of the memoir contains an application of the foregoing general obfervations to the falt-works at Aigle.

On the Analysis of Mineral Waters in general, and particularly thofe of St. Eloy and Bruttelen. By the Count DE Razou

MOWSKI.

In order to examine the properties of water, which is but in a fmall degree impregnated with mineral fubftances, instead of trying what remains, after evaporation, with the mineral acids, the Count advises the ufe of common vinegar, which, he obferves, will diffolve the calcareous and abforbent earths, without affecting the falts; and as the quantity of thefe, in the refiduum, is generally very fmall, he recommends an examination of them by means of the lamp and blow-pipe, which, by drying them, heightens their flavour, and renders them more eafily distinguishable by the tafte; the effect of the flame on them will alfo affift in the determination of their particular kind.

The Count applied this method, in order to analyse the waters of St. Eloy, and of Bruttelen: the former are near Estavayer, in the canton of Fribourg, on the banks of the lake of Neuchâtel; they are, in a very flight degree, aluminous and chalybeate; the iron is diffolved in them by means of fixed air.

The waters of Bruttelen are in the neighbourhood of the Jake of Bienne; they are alfo flightly chalybeate: but the iron which they contain is not diffolved by fixed air, of which the proportion is fo fmall as not to be appreciable, but by a volatile fulphureous acid. Of this fact the Count was convinced by a fynthetic experiment, as well as by analyfis; for he found that iron filings, triturated with fulphur, gave to common water, poured on them, all the properties of the waters of Bruttelen a folution of filver, in the nitrous acid, being mixed with this factititious chalybeate, a number of little pellicles