distilled, left a blackish brown substance, weighing 49 grains. This substance appeared, by experiments made upon it, to be a variety of the artificial tanning matter, much resembling that obtained from resinous bodies by means of sulphuric acid; but it is remarkable, that when a small quantity of nitric acid was added to an aqueous solution of the substance obtained from camphor, and, after evaporation to dryness, the residuum was dissolved in water, a reddish brown liquid was formed, which acted in a manner exactly similar to the tanning substance obtained from carbonaceous substances by nitric acid.

On the Discovery of Palladium; with Observations on other Substances found with Platina. By William Hyde Wollaston, M.D. Sec. R.S. Read July 4, 1805. [Phil. Trans. 1805, p. 316.]

In this paper the author relates circumstantially the series of operations by which he was led to the original discovery of palladium; and as he had an opportunity during the solution of a considerable quantity of platina, of making many observations that have not occurred to others, he undertakes, on the present occasion, to mention those which are most worthy of notice.

He remarks, that the gold which is usually found with platina is a constituent part of the ore of platina itself, when the grains are carefully selected.

The metals iridium and osmium, on the contrary, which were extracted by Mr. Tennant from the black powder that remains after solution of the ore of platina, Dr. Wollaston observes, are not only to be found in that powder which is extricated by solution from the interior of the grains of crude platina, but there exist also other grains originally distinct from those of platina, and consisting of these metals only.

These grains, which he considers as the proper ore of iridium mineralized by osmium, are harder than those of platina, are more brittle under the hammer, and when broken appear to be laminated.

The specific gravity of these grains, he says, is very remarkable, being greater than that of the ore of platina, which in his experiments has not exceeded 17.7, while that of the former is as much as 19.5. It would naturally be supposed that such a density might arise from the presence of a large quantity of platina in them; but the author did not succeed in obtaining any platina from these grains.

Among the various substances that may be separated from the ore of platina by washing, he notices also certain minute crystals of the colour of the ruby. Of these he gives a particular description, but does not undertake the analysis, on account of the very small quantity which he could obtain.

The author next proceeds to the solution of platina, from which he first precipitates the greater part of the platina pure, by sal ammoniac, and the remainder in an impure state by iron, a second metallic precipitate, which he observes consists of various metals intermixed.

It was in attempting to analyse this second metallic precipitate, that he first discovered palladium. After separating from it a quantity of lead, and some iron by muriatic acid, and dissolving out some copper by dilute nitrous acid, he was endeavouring to extract the remainder of the copper by a stronger nitrous acid, when he remarked that the colour of the solution, instead of being blue, as before, turned to a dark brown, in consequence of the solution of some other metallic ingredient. The first thought which occurred to him was, that some iron had remained, and had communicated this colour to the solution; but when he considered that this substance had been more slowly acted upon than copper, he relinquished that hypothesis, and, endeavouring to precipitate the metal by a clean plate of copper, he obtained a black powder, which was redissolved in nitrous acid, and formed a red solution.

The solubility of this precipitate in nitrous acid, showed that it did not consist either of gold or platina: the colour of the solution proved equally that it was neither silver nor mercury; and since the precipitation by copper excluded the supposition of all other known metals, he presumed that he was engaged with a new metallic body, but was not fully satisfied of its existence until he had afterwards precipitated it by mercury, with which it formed an amalgam. By treating this amalgam he procured, in a pure state, the metal to which he afterwards gave the name Palladium, from the planet which had been discovered, nearly at the same time, by Dr. Olbers.

There were various considerations arising out of the preceding experiments, which induced him to consider this as a new simple metal; but since it was possible he might be deceived, he undertook a course of experiments for the purpose of obviating all possible objections. He formed alloys with many different metals, dissolved it in various acids, and, having recovered it from the alloys and solutions so formed, he found it to remain unaltered, retaining its original properties, being nearly infusible by itself, but easily fused with sulphur, with arsenic, or with phosphorus; soluble in nitrous acid, and precipitated from thence by green sulphate of iron, by muriate of tin, by prussiates, and by hydro-sulphurets.

When he found all his endeavours to decompose this substance ineffectual, he became more confident of its being a new simple metal, and accordingly published a concise delineation of its character, but avoided directing the attention of chemists to the source from whence it had been obtained, and thereby reserved to himself a more deliberate examination of many phenomena that yet remained unexplained in the analysis of platina, by which he was subsequently led to the discovery of rhodium, another metallic substance, already published in the last volume of our Transactions.

Experiments on a Mineral Substance formerly supposed to be Zeolite; with some Remarks on two Species of Uran-glimmer. By the Rev. William Gregor. Communicated by Charles Hatchett, Esq. F.R.S. Read July 4, 1805. [Phil. Trans. 1805, p. 331.]

The mineral substance treated of in this paper, is similar to that of which Mr. Davy, some months ago, gave an account, under the title of Hydrargyllite or Wavellite. That which is now described by Mr. Gregor is produced from a mine called Stenra Gwyn, in the county of Cornwall.

Two species of this substance, the author says, are found in the above-mentioned mine; the first, and most common, consists of an assemblage of minute and delicate crystals, in radiated tufts, attached to quartz crystals. These crystals are in general white and transparent; sometimes, however, they have a yellowish hue. They vary considerably in their size, but seldom exceed a quarter of an inch in length.

Among these crystals are frequently seen two kinds of crystalline laminæ; one of them being in the form of parallelopipedons, with truncated angles, and of a green colour; the other forming an assemblage of square plates, varying in thickness, and the angles of which are not always coincident; these are of a bright wax yellow. This last kind is also found adhering to the sides of quartz crystals, in the cavities of granite.

The other species of the substance here treated of, consists of crystals closely compacted together in the form of mammillary protuberances, generally of the size of small peas, and forming a stratum about one eighth of an inch thick, upon quartz, in the cavities or fissures of compact granite. The striæ of these mammillæ diverge from a centre, like zeolite.

The detached crystals of the first species are easily reduced to powder. Their specific gravity, at 56° Fahr., was found to be 2.22. The second, or more compact species, is sufficiently hard to scratch calcareous spar: its specific gravity, at the temperature of 55°, was 2-253.

The crystals of the first species, when suddenly exposed to the action of the blowpipe, decrepitate; if gradually exposed to its action, they grow opake, but show no signs of fusion, even under the strongest heat. Both species, when exposed for some time to a red heat, experience a diminution in weight of about 30 per cent.

Some other experiments upon these substances are related, and a very minute account of the mode in which they were analysed is given; of this we must necessarily confine ourselves to give merely the results.

Fifty grains of the crystals of the first species yielded alumina 29 grs.; silica, 3 grs.; oxide of iron, grs.; lime, grs.; volatilized matter, 14 grs. The sum total of these is Consequently the loss was

47 grs.

23

grs.

50

P

The silica and the lime, Mr. Gregor considers as essential to the composition of this mineral, as he has always discovered them, even in the purest specimens.

In order to examine the nature of the volatilized matter, the author submitted some of the crystals to distillation. A fluid passed over into the receiver, and a white crust was formed in the arch and neck of the retort. The fluid had an empyreumatic smell, very similar to that observed in the fluid distilled from the white crust that surrounds flint. It changed litmus paper to a faint reddish hue. A variety of experiments were made upon the white crust, from the results of which it appeared, that it consisted in part, at least, of an acid, which did not seem to be either the phosphoric or fluoric; nor did its properties entirely agree with those of the oxalic acid, although many of them were similar to those of that acid. A part of the forementioned crust, which firmly adhered to the neck of the retort, was found to contain a portion of lead; this, Mr. Gregor ascribes to the action of the acid on the retort.

Some of the Barnstaple mineral was also tried, and was found likewise to produce the above-mentioned white crust. Mr. Gregor now makes some remarks on the yellow and green crystals already mentioned as accompanying the mineral here treated of, which he says he at first considered as similar to the two species of Uranglimmer examined by Klaproth. The specific gravity of the yellow crystals, at 45° Fahr., was 2.19. Exposed to the blowpipe, they decrepitated violently. They are taken up by phosphate of ammonia and soda without effervescence, and communicate a light emerald green colour to the fused globule. By exposure to a red heat they become of a brassy colour, and lose nearly a third part of their weight.

Several other experiments upon them are related, but their scarcity has, Mr. Gregor says, precluded him from operating on a quantity sufficient for a regular analysis. But he has detected in them oxide of lead, lime, and silica, which have not hitherto been considered as ingredients of Uran-glimmer.

The substance also, which in his experiments was held in solution by ammonia, had some peculiar properties which appeared to distinguish it from uranium.

The green crystals, the author says, do not differ from the yellow, except in containing a little of the oxide of copper.

The Croonian Lecture on the Arrangement and mechanical Action of the Muscles of Fishes. By Anthony Carlisle, Esq. F.R.S. F.L.Š. Read November 7, 1805. [Phil. Trans. 1806, p. 1.]

The muscles of fishes, Mr. Carlisle says, are constructed very differently from those of the other natural classes of animals. The medium in which fishes reside, the form of their bodies, and the instruments employed for their progressive motion, give them a character peculiarly distinct from the rest of the animal creation. Their skeleton is simple, and their proportion of muscular flesh is remark

ably large; but the muscles have no tendinous chords, their insertions being always fleshy. There are, however, semi-transparent pearly tendons placed between the plates of muscles, which give origin to a series of short muscular fibres, passing nearly at right angles between the surfaces of the adjoining plates.

The progressive motion of fishes, our author says, is chiefly performed by the flexions of the trunk and tail; the pairs of fins, which some have considered as analogous to feet, being only employed for the purposes of turning, stopping, altering the position of the fish towards the horizon, and keeping the back upwards. The single fins appear to prevent the rolling of the body whilst the tail is employed to impel it forwards. Each of the fins, which are in pairs, is capable of four motions, viz. of flexion and extension, like oars, and of expanding the rays, and closing them.

Mr. Carlisle now (taking the Cod as a standard of comparison,) describes particularly the mode in which the various motions here spoken of are performed, and then relates some experiments made to determine the effect of the fins on the motions of fishes. For this purpose a number of dace, equal in size, were put into a large vessel of water, and the pectoral fins of one of them being cut off, it was replaced with the others. The result was, that the progressive motion of the fish was not at all impeded; but its head inclined downwards; and when it attempted to ascend, the effort was attended with difficulty.

From another fish, both the pectoral and abdominal fins were taken. The fish remained at the bottom of the vessel, and could not be made to ascend. Its progressive motion was not perceptibly more slow; but when the tail acted, the body showed a tendency to roll, and the single fins were widely expanded, as if to counteract this effect.

From a third fish the single fins were removed. This produced an evident tendency to turn round, and the pectoral fins were kept constantly extended, to obviate that motion.

From a fourth fish all the fins were removed. Its back was kept in a vertical position, whilst at rest, by the expansion of the tail; but it rolled half round at every attempt to move.

From a fifth fish the tail was cut off as close to the body as possible. The progressive motion of the fish was considerably impeded, and the flexions of the spine were much increased; but neither the pectoral nor the abdominal fins seemed to be more actively employed.

From a sixth fish all the fins and the tail were removed. It remained without motion, floating near the surface of the water, with its belly upward.

The above experiments were repeated on the roach, the gudgeon, and the minnow, with similar results..

Mr. Carlisle now observes, that the muscles of fishes differ very materially in their structure from those of other animals; that they are apparently more homogeneous; that their fibres are not so much fasciculated, but run more parallel to each other, and are always