which have been deposited at the same time with the clayey basis. I consider traptuff not as a breccia, but as an original rock. Dr. M. observed rolled masses of granite, gneiss, and other primitive rocks upon Staffa. He supposes that this had escaped the observation of preceding observers. But this is a mistake. I am pretty sure that the same observation was made by Faujas de St. Fond; though I have it not in my power at present to consult his book. Mr. Mills mentions the same thing in his paper published in the Philosophical Transactions, 1790, vol. lxxx. p. 73.

XXIII. On Vegetable Remains preserved in Chalcedony. By Dr. Macculloch.-Nothing is more common than to observe in agates arborizations having a close resemblance to plants. The same thing occurs in chalcedony. Daubenton many years ago wrote a paper on the subject, in which he even names the species of plant contained in the chalcedony which he examined. Dr. M. likewise collected a great many of these chalcedonies, and the result of a careful examination satisfied him that true plants, chiefly confervas and mosses, occur in chalcedonies; though very perfect imitations of them are often produced by chlorite. To distinguish the true plant, he applies sulphuric acid to the mineral. If the acid be blackened he concludes that a true vegetable exists in the stone; if not, he considers the appearance as owing to chlorite. It would be difficult to convince me that such delicate vegetables as confervas and mosses can exist in chalcedonies, without so much as their colour or texture being altered. I am rather disposed to ascribe these appearances to manganese, iron, &c. occasionally mixed with bitumen. This bitumen I conceive colours the sulphuric acid, and leads to the conclusion that vegetable matter is present. The fact that some of the lines in agates are blackened by sulphuric acid, mentioned by Dr. Hamel in a late number of the Annals, shows that bituminous matter is a pretty frequent constituent of agates.

XXIV. On the vitreous Tubes found near to Drigg in Cumberland. Compiled by the secretaries from several communications. -These tubes have been found in hillocks of drifted sand at the mouth of the Irt in Cumberland. The first account of them was sent to the Society in 1812 by Mr. Irton of Irtonhall, Cumberland. Three were found in a single area of 15 yards, forming a hillock elevated 40 feet above the level of the sea. The diameter of each was about an inch and a half. Within they consist of a very hard glass, which strikes fire with steel. One of them was traced to the depth of 30 feet without terminating, though it became smaller. The sand falling in prevented the continuance of the excavations: the sand consists of quartz mixed with grains of horn-stone porphyry. By the blow-pipe urged by a stream of oxygen gas, this sand was imperfectly vitrified, so as to resemble the inside of the tubes. The most probable opinion is, that these tubes have been formed by the action of lightning.

VOL. VI. N° I.

E

II. An Index to the Anatomical, Medical, Chirurgical and Physiological Papers contained in the Transactions of the Royal Society of London; from the commencement of that Work to the end of the year 1813; chronologically and alphabetically arranged. Callow, &c. London.

The Philosophical Transactions contain perhaps a greater number of valuable papers on medical and physiological subjects, than any other publication whatever. But they are so voluminous that it is a very difficult and laborious task to ascertain what they contain. Hence the utility of good indexes, which serve greatly to facilitate the investigations of the medical student. The present Index is very well executed, and calculated in every respect to answer the purposes for which it was intended.

ARTICLE XIV.

Proceedings of Philosophical Societies.

ROYAL SOCIETY.

On Thursday the 25th of May, a paper by Dr. Parry was read on the cause of the pulsation of the arteries. He stated the opinion of Haller, which is generally received by physiologists, and that of Bichat, who had rejected Haller's explanation in consequence of his dissections of living animals. Dr. Parry then stated the results which he himself had obtained by laying open the arteries of living sheep and rabbits. No alteration in the size of the artery could be perceived, but a motion of the artery backwards and forwards, corresponding to the inspiration and expiration of the animal. Dr. Parry conceives that the artery is a tense tube always full of blood, and that when its diameter is diminished by external pressure, the blood makes an effort to restore the original size. Hence the pulsation. I do not see clearly how this supposition will account for the various diseased states of the pulse well known to medical men, unless we ascribe the aberrations in all these cases to the heart.

At the same meeting, part of a paper by Mr. Donovan was read, giving an account of a new vegetable acid, discovered by him in the juice of the berries of the sorbus aucuparia, together with some observations on malic acid. He extracted the juice of the ripe berries by pressure, precipitated by acetate of lead, washed the precipitate in boiling water, and threw the whole upon the filter. A hard white mass remained upon the filter, and the liquid which passed through deposited, on cooling, fine, white, silky, needle-form crystals. Scheele had stated the acid in these berries to be the malic. But malate of lead had never been observed to crystallize. To clear up the subject, Mr. Donovan saturated the juice of ripe apples with potash, and precipitated the liquid by acetate of lead. The

precipitate treated with boiling water, as in the preceding case, yielded similar silky crystals; but the substance remaining on the filter was a soft magma. Gooseberry juice treated in the same way yielded no crystals; nor raspberry juice, nor the juice of elder ber ries, nor of sedum tectorum, nor green apples. Thus it appears, that acetate of lead precipitates two different acids in the first two liquids. The first an acid not hitherto observed, which readily forms a supersalt with oxide of lead soluble in hot water; and this solution on cooling deposits the neutral salt in silky crystals: the second malic acid, which forms with oxide of lead a salt not capable of crystallizing. To obtain the new acid in a state of pu rity, the colourless silky crystals are to be treated with a quantity of sulphuric acid capable of saturating the greater part, but not the whole, of the oxide of lead present. The liquid being filtered to separate the sulphate of lead, a current of sulphureted hydrogen is driven through it till the whole remaining oxide of lead is thrown down. The filtered liquid is now boiled for some time, and then exposed to the air for a few days to get rid of the sulphureted bydrogen.

On Thursday the 1st of June, Mr. Donovan's paper was continued. To the acid thus obtained he gave the name of sorbic acid. It possesses the following properties. It is colourless. Its taste is intensely sour, and it reddens vegetable blues. It does not crystallize. It does not readily undergo spontaneous decomposition. Mr. Donovan kept a quantity of it in a phial for a year: no other change happened except the deposition of a very small quantity of mucilaginous matter. It combines with oxide of lead in three proportions, forming, 1. Subsorbate of lead, which is a hard white insoluble powder. 2. Sorbate, which may be obtained either in powder or in crystals, and which is likewise insoluble. 3. Supersorbate, which does not crystallize. The alkaline supersorbates may be all obtained in the state of crystals. It forms soluble salts with barytes, lime, and magnesia. It does not combine with alumina. These properties sufficiently distinguish this acid from the malic.

Mr. Donovan likewise related his experiments on the preparation of malic acid. He found none of the methods recommended by Scheele capable of furnishing pure malic acid. He considers Vau quelin's process for preparing malic acid from the juice of the se dum tectorum as the only one that yields a tolerably pure acid. I may observe here, that about 10 years ago I made some experi ments on the preparations of malic acid, and found that unless it be freed from mucilage before precipitation with lead, it cannot af terwards be separated from a considerable quantity of gummy mat ter which seems to fall down in combination with the lead. I as cribe most of the difficulties which have occurred to chemists in preparing this acid, to not animadverting to this circumstance.

Mr. Donovan conceives it likely that the bitter principle which exists at first in various fruits and disappears as they advance to maturity, may be the basis of some of the vegetable acids.

At the same meeting a paper by Sir Everard Home, Bart. on the respiratory organs of some genera of vermes that live in water, was read. These organs consist of a number of openings on both sides of the neck, which lead into spherical or flattened balls, Water passes through these openings into the bags, and is afterwards thrown out again. The reason why the water does not enter at the mouth as in fishes, is because these animals, as the leech, require their mouths for suction, either to procure food or to fasten themselves to other bodies.

On Thursday the 8th of June, a paper by Dr. Brewster was read on the multiplication of images and colours which accompany them in some specimens of Iceland spar. Towards the end of the session of the Royal Society, the number of papers presented is usually so great, that only a small portion of them can be read to the Society. On this account nothing can be added to the notice of Dr. Brewster's discovery relative to this subject given in the last number of the Annals of Philosophy.

At the same meeting a paper by C. Babbage, Esq. was read, entitled, On the Calculation of Functions. This he informed us is a new species of calculus, which will require new methods of investigation. But as only the introduction of the paper was read, it is impossible to give any farther account of it.

At the same meeting a paper by Dr. Herschell on the satellites of the Georgium Sidus, with some observations on the space penetrating power of telescopes, were also read. The object of the paper was to furnish data to astronomers to determine the number and orbits and periodical times of the satellites of this very remote planet. He described the orbits and periods of two of the satellites, supposed that another existed within them, and probably three others without them..

On Thursday the 15th June, a paper by Sir Everard Home, Bart. was read, on the mode of generation of the lamprée and myxine. He found by a great many dissections at different periods during the summer, that these animals are all hermaphrodites; those, which were supposed to be males, producing eggs as well as the supposed females.

At the same meeting a paper by Anthony Carlisle, Esq. was read, on the connection between the extravascular and vascular parts of animals. Hair, feathers, nails, hoofs, are extravascular substances, and possess no vessels. The chief object of the paper was to show, that the shells of shell-fish and snails are likewise without vessels. They cannot be injected. Their membranes do not exhibit the same appearance as those that contain vessels. When a piece of snail-shell was broken off, the injury was repaired by a viscid substance applied internally, and then layers of calcareous matter were laid over it.

At the same meeting a paper by John George Children, Esq. was read, on the effects of a very large galvanic battery. It consisted of 20 pair of zinc and copper plates 6 feet long and 2 feet 6 inches

broad, joined together by straps of lead and plunged in a mixture of nitric and sulphuric acids, diluted with from 20 to 40 times their weight of water. By this battery metallic wires were ignited in the following order, beginning with the wire most easily igPlatinum

nited.

Iron

Gold

Copper
Silver
Zinc.

Tin and lead are so fusible, that with them the experiment could not be tried. Mr. Children considers the ignitability as the inverse of the conducting power of the metals; therefore platinum conducts worst and zinc best of the above six metals. When the two poles of the battery were connected by two parallel platinum wires of different sizes, the thick wire was ignited and not the fine one; but when the two wires were tied one to the end of the other, the fine wire was ignited first.

Iron wire was slit, some diamond powder put into the slit, and this powder surrounded by iron wire above and below. The wire was faintly ignited. The diamond powder disappeared and the iron was converted into steel and partly fused. This demonstrates the truth of Clouet's original experiment, which was afterwards verified by Sir George Mackenzie. Iridium was fused by the battery and reduced to a porous globule of the specific gravity 18'6. Oxide of tantalum was fused and reduced. The metal was of a yellowish colour and brittle. Oxide of cerium was fused without being reduced. This was the case also with oxide of titanium. Oxide of tungsten was reduced and fused. The metal was grey and very heavy. Oxides of molybdenum and uranium were likewise fused and reduced, and both metals were brittle.

The titles of the following papers were read, in order to entitle them to insertion in the next volume of the Transactions; want of time rendering it impossible to read the papers themselves at full length.

Considerations on the Solution of Bodies in Liquids, by Mr. Daniell.

On the Dispersive Properties of the Air, by Mr. Stephen Lee. Considerations on the Vascular System of Animals, by Dr. Philips. The Polar Distances of 30 Circumpolar Stars, by John Pond, Esq. Astronomer Royal.

The Society adjourned during the long vacation.

N.B. In the last number of the Annals of Philosophy, the numerical results of several of Mr. Porrett's analyses of Prussic acid and its compounds were inaccurate, The following are the correct numbers, which Mr. Porrett has been so obliging at to communicate.

100 Prussiate of mercury are composed of

Prussic acid.....

Peroxide of mercury.

13.8 86.2

100.0