ing to the length of time that has elapsed since their formation; and to each of these species he assigns determinate characters. First, those of the most recent formation possess open craters, and are surrounded with scoria, and different bodies which exhibit the immediate effects of fusion. In the second kind, the craters and scoria are no longer to be found, but the currents of lava may be traced, covering the horizontal strata of the earth, and intersected by streams and vallies. In the last and most antient species of volcanoes, the lava is difcovered below the horizontal strata, and not unfrequently even beneath the waters of the ocean. How far this hypothesis will be found to accord with the phænomena of nature must be determined by those who have more opportunities than we possess, of diving into the depths of geological science: but it wears a plausible appearance, and, if established, would obviously lead to some important conclusions, and tend to correct many erroneous speculations.-We are concerned to ob. serve an author of acknowleged merit, like M. DESMAREST, speak in an arrogant and supercilious manner of certain Scotch and Genevese philosophers,' who happen to differ from him respecting the formation of basalt.

Memoir on the Comparative Nature of the Gaseous Oxid of Azote, or the Nitrous Oxid of Mr. Davy, and of Nitrous Gas. by MM. FOURCROY, VAUQUELIN, and THENARD.-After some observations on the history of the nitrous oxid, in which is justly ascribed to Dr. Priestley the discovery of most of its properties, except its action on the animal economy, the authors give an account of the experiments which they instituted for the purpose of analyzing the two gases. They performed the decomposition by transmitting them over iron filings, in hot earthen tubes. We have then a relation of the effects produced on M. VAUQUELIN, by the respiration of the nitrous oxid; which seems to have partaken more of the nature of asphyxia, than of that increased action which was experienced by Mr. Davy and his friends. On the whole, we do not think that this paper is worthy of the talents of the three chemists whose names appear in the title.

New Experiments on Cow's Milk, by MM. FOURCROY and VAUQUELIN. We are here presented with some important additions to the knowlege which we previously possessed, respecting the composition of this fluid. It has been already announced that the acid which is developed during the coagulation of milk, and which was supposed by Scheele to be endued with specific properties, is merely the acetic acid, united to a portion of animal matter; and in the paper before us, the authors

give in detail the experiments on which the opinion is founded. They also state that milk, when fresh drawn, contains a small quantity of acetic acid: that the phosphate of magnesia, as well as that of lime, has been detected in this fluid; and that it likewise contains a small quantity of iron, probably also in the state of a phosphate. The animal matter which is united to the acetic acid, they suppose to be similar to the gluten in wheat.

Memoir on Guano, or the Natural Manure of the Islands of the South Sea, near the Coast of Peru. By the Same.-M. Humboldt, daring his travels in South America, observed a singular substance on some of the small islands near the coast of Peru, which is employed for the purpose of manure in the neighbouring parts of the continent, and seems to possess the requisite properties in a very high degree. It forms a stratum of considerable thickness, and is dug up in the way in which we obtain peat in this country. From a chemical analysis, it was found to consist principally of uric acid, partly saturated with lime and ammoniac; and it contains oxalic and phosphoric acids in the same state of combination, as also a quantity of a fatty substance. The origin of the guano is doubtful; it agrees in many particulars with the excrement of birds: but the large masses in which it is obtained are almost incompatible with the idea that it can be derived from a source which appears so inadequate.

Analysis of Tabasheer. By the Same. This is a peculiar substance, found in the joints of the bamboo. It had been previously ascertained that silex was a principal ingredient in it; and the present analysis shews that, in addition to silex, it contains pot-ash and lime.

Memoir on falap. By M. DESFONTAINES.-This valuable article of the Materia Medica was long employed as a purgative, before the nature of the plant was known from which it was procured. It was at length discovered in Mexico, and appears to belong to the genus convolvulus. We have in this paper an accurate botanical description of the plant, and an account of its natural history, accompanied by two engravings.

Result of the different Methods employed to give to Plates and Bars of Steel the greatest degree of Magnetism. By M. CouLOMB. Referring to the opinions which he has formerly published on this subject, the author remarks that there is a point of saturation, beyond which iron cannot be rendered more magnetical, and that it is of great importance to ascertain with accuracy when the metal has arrived at this condition. method which he recommends is to suspend the magnet horizontally

Hh 2

The

rizontally by means of a silken thread, and to observe the number of oscillations that are performed in a given time; the quickness of the oscillatory motion increasing with the intensity of the power. We have afterward some remarks on the best method of magnetizing bars;-the one recommended by M. COULOMB is nearly similar to that which was formerly proposed by Knight.

Memoir on several Species of Unknown Fossils. By M. DESMAREST. In this paper, which is the first of a proposed series, we have a minute account of a fossil considerably resembling the oyster. The memoir is accompanied with illuftrative engravings.

Chemical Observations on the Art of Scouring or Cleansing Stuffs. By J. A. CHAPTAL.-After having remarked that the art of scouring or cleansing stuffs or cloths of all kinds depends entirely on chemical principles, and requires a very extensive knowlege of the science, in order to explain all the operations that are employed in it, M. CHAPTAL describes in detail the nature of the various kinds of substances by which cloth is injured, and the appropriate means by which they may be removed. Although we do not find that the paper possesses any thing particularly new, it contains much useful information, clearly stated, and well arranged.

Memoir on the Spongy Substance of the Uterus, submitted to some Experiments, by M. TENON.-In these experiments, portions of the spongy substance of the uterus were immersed in different sorts of fluids; as water, alcohol, urine, &c. As might have been predicted, in some the substance was rendered firmer, in consequence of the coagulation of one or more of its constituent parts; while in others it was softened, from the effects of a partial solution. We do not see that the experiments can lead to any important conclusion; and we think that M. TEMON's application of them to the living body is quite inadmissible.

Memoir on the Chemical Nature of Smutted Wheat. By MM. FOURCROY and VAUQUELIN.-This substance had been previously submitted to experiment, and had been found to manifest acid properties, but the nature of the acid was not ascertained. From the researches of MM. FOUR CROY and VAUQUELIN, it would seem to be the phosphoric acid, united to ammoniac, magnesia, and lime; the acid, however, existing in excess. It also contains a vegeto-animal matter, a fœtid oil, and a carbonaceous substance. All its natural constituents are quite changed; and it no longer affords gluten, starch, nor sugar.

Memoir on the Discovery of a new Inflammable and Detonating Matter, formed by the Action of Nitric Acid on Indigo and Animal Matter. By the Same.-The nitric acid dissolves indigo with facility, and converts part of it into a substance of a deep yellow colour, and of intensely bitter taste; which, when gently heated, has the property of detonating with considerable vio lence. A substance, possessed of similar properties, had been formerly procured by other chemists, from different animal matter, and M. Welther had even observed its detonation.

Memoir on the Phanomena and Products which Animal Substances afford, when treated with Nitric Acid. By the Same.The action of nitric acid on animal substances was first accurately noticed by M. Berthollet, and led to some important discoveries respecting the composition of these bodies. He, however, principally directed his attention to the gaseous products that arise from this action; while, in the present paper, the authors give a minute account of the change that is produced in the animal matter, and in the acid. These both acquire a deep yellow colour, which appears to be owing to the formation of a peculiar acid substance, considerably similar to that which is described in the preceding paper. The fluid is found to contain sulphate of lime, and oxalate of pot-ash, and likewise a quantity of the malic acid.

Tuo Memoirs on Crude Platina, on the Existence of several Metals in it, and on a new Species of Metal in this Mineral. By the Same. These papers contain a number of accurate experiments performed on platina, which, when they were read to the Institute, must have appeared interesting and important. At the time, however, that the French chemists were engaged in these researches, Mr. Tennant and Dr. Wollaston were examining the properties of platina, and carried their discoveries to a considerably greater extent. The properties of the new metal, to which Mr. Tennant has given the name of iridium, are pretty clearly indicated by MM. FOURCROY and VAUQUELIN; and they notice some phænomena which must be attributed to the presence of osmium, the other of Mr. Tennant's new metals, but they do not appear to have had the least suspicion of its existence. They conjecture that palladium may be a compound of the new metal, i. e. iridium, and platina. They find that crude platina also contains titanium and chromie; the former existing in the state of an oxid, the latter in that of an acid. They also detected the sulphuret of copper.

Remarks on the Membranous Bag which the Peritoneum furnishes to the Uterus. By M. TENON.-This paper may be con

Hh 3

sidered,

sidered, in some respects, as a sequel to a preceding mémoir by the same author, which we noticed above. (P..468.) After having observed that the back part of the bladder is in immediate contact with the neck of the uterus, he supposes that the urine may transude, and act on this part. We have already expressed our opinion of M. TENON's experiments, and we are oblied to pass an equally unfavorable judgment on this application of them.

Memoir on the different Kinds of the Mammiferous Genus, named Fourmillier or Myrmecophaga, or Ant-eaters. By B. G. E. LACÉPÈDE.-The name of this writer, so celebrated in zoology, will draw the attention of the naturalist to the present paper. He observes that all the animals belonging to this family are remarkable as well for their habits as their forms, and particularly for the small aperture of the mouth; for the length, roundness, and thinness of the tongue; and for the facility with which they can extend it beyond their mouth. It is here stated that this genus Fourmillier contains but three species known to naturalists, viz. F. Tamanoir, (M. Jubata,) F. Tamandua i, (M. Tetradactyla,) and F. Didactyle, (M. Didactyla). Specimens of each of these may be seen in the National Museum of Natural History.

Memoir on the Measurement of Heights by the aid of the Barometer. By L. RAMOND.-In order to ascertain the height of mountains with precision, by means of the barometer, many experiments must be made in different states of the air, and in different degrees of cold and heat. M. RAMOND seems fully aware of the numerous errors to which this mode of mensuration is subject, and has sedulously endeavoured to obviate them. He has chosen the seasons most favourable for the operation, has employed the best instruments, has corrected the temperature of the mercury by the thermometer, and has scrupulously compared his results with those that have been obtained by other philosophers. It is impossible for us to give the calculations and tables contained in this very elaborate and extensive paper; which sufficiently proves that, by due attention to all circumstances, measures may be taken by the help of the barometer, with a great degree of exactness.

We have not yet received the other parts of this VIth Vol. of the Society's Reports; and indeed such is the present state of the continent, that it is with difficulty and hazard that any foreign publications are now procured in this country.

ART.