schistus found at Reykum, one of the great spouting hot springs in Iceland. The singularity of this substance is, that a great part of it consists of leaves, (evidently those of the alder,) interposed between the different lamellæ. These leaves appeared to be in the state of charcoal; but on more close examination, no doubt remained of their still retaining a certain portion of some of the other principles of the original vegetable, such as extract and resin. This, in fact, is the result of an extensive chemical process, from which we learn that the schistus, taken collectively, yields, besides silicia, alumina, and oxide of iron, a certain proportion of water and of vegetable matter, and that it evidently belongs to the family of argillaceous schistus.

The above process may be considered as preliminary to that on the Bovey coal, in which the vegetable characters are more obliterated than in the leaves of the schistus. This coal, we are told, bears a great resemblance to a fossil found in Iceland, called Surturbrand; the strata of both being composed of trunks of trees, which have completely lost their cylindrical form, and are flattened, as if they had been subjected to an immense degree of pressure. On inquiring into this last-mentioned circumstance, our author produces his reasons for believing that it is not the effect of the mere pressure of a superincumbent stratum, but also of a certain change in the solidity of the vegetable bodies, and a powerful mechanical action, produced by the contraction of the argillaceous strata in consequence of desiccation.

Here follows the analysis of the Bovey coal. The results point out a great resemblance between this substance and that which forms the leaves contained in the Iceland schistus. The only exception is, that the leaves contain some vegetable extract, none of which could be discovered in the coal. Both consist of woody fibre in a state of semicarbonization, impregnated with bitumen and a small portion of resin, perfectly similar to that which is contained in many recent vegetable characters, and is but partially and imperfectly converted into coal; so, in like manner, some of the other vegetable principles have only suffered a partial change. Next to this woody fibre, resin is thought to be the substance which, in vegetables passing to the fossil state, most powerfully resists any alteration, and which, when this change is at length effected, is more immediately the substance from which bitumen is produced.

This opinion, that the vegetable extract and resin are the parts of the original vegetables, which retain their nature after other portions of the same have been modified into bitumen, is corroborated by the analysis which here follows, of a singular substance which is found with the Bovey coal. Dr. Milles, who first mentioned this substance, considered it as a loam saturated with petroleum; but our author, on mere inspection, decided that it is not a loam, but a peculiar bituminous substance. After a description of its external appearances, and some of its relative properties, we come to the analysis; from which we collect, that this is a peculiar and hitherto unknown substance, which is partly in the state of vegetable resin, and partly in

that of the bitumen called Asphaltum; the resin being in the largest proportion, 100 grains affording 55 of resin, and 44 of asphaltum. Thus we have an instance of a substance found under circumstances which constitute a fossil, although the character of it partly appertain to the vegetable and partly to the mineral kingdom

In the concluding section the author enters into an inquiry on the action of alcohol on resins and bitumens. Its power of dissolving the former is well known; but, contrary to the adopted opinion, he found that it also acted on bitumen, though indeed in a slight degree. His chief object was to ascertain whether a small portion of resin is contained in any of the bitumens, or, if not, to determine the nature of the substance which can be separated, although very sparingly, from those substances by digestion in alcohol. The results prove that the small portion which can be extracted from bitumen by digestion with alcohol is petroleum.

From a general view of the subject, the author thinks himself justified in asserting, that in bitumens the process of transformation appears to have been completed; whereas in the Bovey coal, and especially in the substance which accompanies it, Nature seems to have performed only half of her work, and, from some unknown cause, to have stopped in the middle of her operations. By this circumstance, however, much light is thrown on the history of bituminous substances; and the opinion that they owe their origin to the organized kingdoms of nature, and especially to the vegetable, which hitherto had been supported only by presumptive proofs, seems now to receive a full confirmation, although the causes which operate these changes on vegetable bodies are as yet undiscovered.

On two Metals, found in the black Powder remaining after the Solution of Platina. By Smithson Tennant, Esq. F.R.S. Read June 21, 1804. [Phil. Trans. 1804, p. 411.]

From a few experiments the author made in the course of last summer on this powder, he concluded, that it does not, as was generally believed, consist chiefly of plumbago, but that it contains also some other unknown metallic ingredient. Since those experiments, two French chemists, Messrs. Descotils and Vauquelin, having likewise examined that substance, found the same new metal; but neither of them observed that it contains moreover another metal different from any hitherto known.

The black powder used in the process, which is the subject of this paper, was obtained from platina carefully separated from all extraneous particles; so that the above ingredients, if found, must have been contained in that metal.

The first set of experiments relates to the effects produced by this powder when alloyed with other metals. It combines readily with lead; but the compound, even when the lead greatly predominates, is not very fusible. With bismuth, zinc, and tin, the effects are nearly similar; but with copper, a strong heat produces a much more

M

intimate union. The union of this substance with silver and gold produced upon it very little alteration; but, what is most remarkable, it could not be separated from these metals by the usual processes of refining. The alloys retain a considerable share of ductility; and the colour of that which is alloyed with gold is not materially different from that of pure gold.

The next experiments relate to the analysis of the black powder, and the properties of the two metals which enter into its composition. The method of dissolving the powder was similar to that employed by M. Vauquelin, viz. by the alternate action of caustic alkali and of an acid. The acid solution was found to contain that particular metal which has been noticed by Descotils. And of this metal, a considerable number of characters are here described, in addition to those already mentioned by the French chemists.

As to the alkaline solution, which Vauquelin considered as containing a portion of oxide of chrome, it is observed, that though some kinds of platina may contain chrome, and of course exhibit a certain quantity of it in its black powder, yet the precipitate which, upon accurate investigation, is yielded by it affords a very volatile metallic oxide, which evidently has not the characteristic qualities of that metal. As it is expedient to assign a specific name to every new substance, our author wishes to distinguish this precipitate by the appellation of Osmium, from the strong smell it emits. After showing in what manner it may be expelled from the alkali by an acid, and obtained by solution with water and distillation, the author mentions many of its relative properties and characteristic qualities. The most striking test of this oxide, we are told, is the mixture of its solution with an infusion of galls, which presently produces a purple colour, and becomes soon after of a deep vivid blue. It parts freely with its oxygen to all metals excepting gold and platina.

On a new Metal, found in crude Platina. By William Hyde Wollaston, M.D. F.R.S. Read June 21, 1804. [Phil. Trans. 1804, p. 419.]

Dr. Wollaston having conceived an idea that, in addition to the two new metals the preceding paper states to have been discovered in platina, the fluid which remains after the precipitation of that metal by sal-ammoniac, and which is likely to contain the more soluble parts of the mineral, might, on further examination, be found to contain some other substance worthy of our attention; and, in fact, having instituted an accurate analysis, of which the present paper contains a full detail, he thinks he has proved the existence of another unknown metal, to which, for the sake of distinction, he ascribes the name of Rhodium, from the beautiful rose-colour of the salts containing it. In the course of his detail, he likewise states the results of various experiments, which, he says, have convinced him that the metallic substance which was last year announced to the public by the name of Palladium, is contained (though in very small proportion,) in the ore of platina.

The process referred to for separating these several ingredients from each other yielded, in fact, a pure metallic button, not malleable. but uniting readily with all the other metals that have been tried, except mercury, and whose specific gravity appeared not less than 11. This is the rhodium, which is here announced for the first time.

The palladium was precipitated from the alcohol employed for washing the salt of rhodium: it was yielded, indeed, in a very small proportion, but in sufficient quantity, however, to prove that it is actually a simple metal residing in platina, and to induce a suspicion of some error in Mr. Chenevix's investigation, who thought it a compound of platina and mercury; but our author candidly adds, that he has made several attempts to imitate the synthetical experiments of that chemist by solution and amalgamation, but without

success.

The Croonian Lecture on Muscular Motion. By Anthony Carlisle, Esq. F.R.S. Read November 8, 1804. [Phil. Trans. 1805, p. 1.]

Admitting that there are subjects in the economy of nature which will ever elude our most attentive observation, and that many institutions similar to our Croonian Lecture will probably never attain the end for which they were founded, it cannot, however, be denied that several of them, and ours in particular, have at different times brought forward various collateral, and some of them not unimportant facts, which have in some measure contributed to extend our knowledge of nature. This latter is the point of view in which the present communication is to be considered; concerning which the author says, that, waving the investigation of the general theory of muscular motion, he shall limit his present inquiry to certain circumstances which are connected with this motion, considered as causes, or rather as a series of events, all of which contribute more or less as essential requisites to the phenomena. The changes which obtain in muscles during their contractions or relaxations, and their corre. sponding connexions with the vascular, respiratory, and nervous systems, are, he declares, the chief objects of his present investigation. The lecture is divided into six sections, of which the following are the heads, together with some of the most prominent facts contained under each of them; the nature of the performance, which consists chiefly of insulated facts, and our limits in point of time, precluding us from being so minute in our analysis as the importance of the subject may be thought to require.

Sect. 1. Of the physical and sensible properties of muscles, considered as distinct parts of an animal, and as peculiar organs.—In describing the fasciculated texture of the fibres which compose a muscle, and the elasticity of these fibres during the contracted state of the muscle, the author advances an opinion, that this elasticity appears to belong to the enveloping reticular or cellular membrane, and that it may be safely assumed that the intrinsic matter of muscle is not elastic.

'The attraction of cohesion in the parts of muscle appears to be strongest in the direction of the fibres, and to be double that of the contrary or transverse direction. When muscles cease to be irritable, this attraction in the direction of the fibres is diminished; but it remains unaltered in the transverse direction.

When muscles act more powerfully or more rapidly than is proportionate to the strength of the sustaining parts, they do not usually rupture their fleshy fibres, but generally break their tendons, or even an intervening bone; whence it is inferred, that the attraction of cohesion is more active and powerful in the contracted state of the muscle than during its relaxed or passive state.

The muscular parts of different classes of animals vary materially in colour and texture; and such variations occur not unfrequently in different parts of the same individual.

Sect. 2. Of the anatomical structure of muscles, and their relations with other parts of the animal body.-The lecturer in this section professes to give no more than a rapid sketch of the history of muscular structure. One example of the origin of a muscle he deduces from the process of the incubated egg: but here it remains doubtful whether the rudiments of the punctum saliens be part of the cicatricula organized by the parent, or merely a structure resulting from the first process of incubation. The anatomical structure of muscular fibres, he next observes, is generally complex, according as they are connected with membrane, blood-vessels, nerves, and lymphæducts; which seem to be only appendages of convenience to the essential matter of muscle.

A muscular fibre, being carefully inspected in a powerful microscope, is found to be a solid cylinder, the covering of which, as had already been intimated in a previous part of the lecture, is a reticular membrane, and the contained part a pulpy substance, irregularly granulated, and of scarce any cohesive power when dead.

The arteries articulate copiously upon the reticular coat of the muscular fibre; they anastomose with corresponding veins; but this continued canal is not supposed to act in a direct manner upon the matter of muscle. In what manner the capillary arteries terminating in the muscular fibre may effect all the changes of increase in the bulk or number of fibres, in the replenishment of exhausted materials, and in the repair of injuries, is as yet matter of conjecture; but these arteries, it is thought, must be secretory vessels for depositing the muscular matter, the lymphæducts serving to remove the superfluous fluids and the decayed substances which are unfit for These lymphæducts appear to receive the fluids they contain, not, as has been represented, from the projecting open ends of tubes, but from the interstitial spaces formed by the reticular or cellular membrane.

use.

The functions of nerves in the muscular system are the next object of contemplation. These also, it seems, terminate in the reticular or cellular membrane, the common integument, and the connecting medium of all the dissimilar parts of an animal. We have to regret