Iodine. There is only one recorded specific gravity of this element--viz., that by Gay Lussac. I have estimated the specific gravity of two fine specimens in my laboratory, and take the mean of these results ::

Tabulating these results, and bringing into comparison with them. the roots of the atomic weights, we have the following striking ac

2. Some Miscellaneous Observations on the Tadpole, and on the Albumen of the Newly-laid Egg. By John Davy, M.D., F.R.S. Lond. and Edin.

(This paper appears in the present number of the Journal.)

3. On Acupressure, a New Method of Arresting Hæmorrhage. By Professor Simpson.

3d January 1860.

The following Communications were read:

1. Some Miscellaneous Observations on the Growth of Birds, their Specific Gravity, and on the Stomach of Fishes in Relation to Digestion. By John Davy, M.D., F.R.S. Lond. and Edin.

(This paper appears in the present number of the Journal.)

16th January 1860.

1. Suggested Explanation of Messrs Carrington and Hodgson's recently observed Solar Phenomenon. By Professor C. Piazzi Smyth.

The Royal Society of Edinburgh having been the arena wherein Professor W. Thomson first described his calculations and admirable extensions of Mr Waterston's meteoro-dynamic theory of solar light and heat, I beg leave to call the attention of the same learned Society to an apparent instance of confirmation which that theory appears to me to have received, by a phenomenon of very unique character, recently observed in an independent and most satisfactory manner, by either of two able scientific men-viz., Mr Carrington of the Observatory, Red Hill, and Mr Hodgson at Highgate.

The respective observations of these gentlemen are to be found in the monthly notices of the Royal Astronomical Society for November 1859, and seem quite sufficient to prove, after making all due allowance for the different instrumental methods employed in either case, and the peculiar nature of the subject observed, that on September 1, at about 11 h. 18 m. A.M., Greenwich time, two small telescopic bodies of light, in close proximity, and elongated in the direction of their motion, suddenly burst into view on the surface of the sun, not very far from its central portion, than which they were very much brighter. They moved side by side in arcs nearly parallel with the plane of the ecliptic; first for a time increasing in brightness, and then again gradually fading away, so as to be quite lost in about five minutes after their first appearance. Though apparently on the surface of the sun, yet that appearance was considered to arise from optical projection only, as they did not alter the shape of a group of large black spots, which lay directly in their paths. They must, nevertheless, have been exceedingly close to the surface; and on that supposition, the paths which they described during their period of visibility must, from their angular extent, have measured about 35,000 miles, giving a mean rate of 117 miles per second.

The first remark that we may make on the facts of observation, save that nothing so momentary has ever been witnessed before by astronomers, is, that 117 miles per second constitutes a velocity so exceedingly great, that we can only look to the gravitation influences of the sun for its efficient producing cause. Nevertheless, we are at the same time bound to acknowledge, that the full rate of orbital motion, for a body nearly in contact with the surface of the sun, is rather over 276 miles per second; and the rate of falling to the sun from infinite space, considerably more. Evidently, then, something prevented these bodies of September 1 from moving at their full rate, and produced a retardation in their orbit equal to 159 miles a second, to take Professor W. Thomson's form of the gravitation theory as the more probable.

What that retarding something was, it is not so much to our purpose now to inquire, as long as we can show that it is not altogether a baseless supposition, to assume the existence of any extensive material belonging to the sun, outside his visible, luminous surface. When we find our solar meteors of September 1 moving at a rate slower by 159 miles a second than they should do according to the laws of gravitation, the simplest assumption that we can make is, that there has been a mechanical retardation to that amount. Let this be granted, and then it necessarily follows from the dynamical theory of heat, that precisely in accordance with the disappearance of motion will be the appearance of heat.

According to Mr Waterston's form of the theory, and even the first expression of Professor W. Thomson's also, where the sun is fed by lumps of meteoric matter, there is some difficulty in explaining why the occurrence of luminous meteors in the sun is not frequently observed, if remarkably visible in one instance; while, according to the subsequent modification of the latter's view, the generality of meteors must be distilled away into impalpable clouds of finely-divided meteoric matter some time before they actually reach the sun; and neither gentleman had expected that an actual impact would ever be seen by mortal eye.

These objections, however, will be at once, to a great extent, relieved by the very fair assumption of as superior a mass to the September 1st meteor, over the generality of those which fall to the sun, in any and every manner, as men have already recorded of those which have actually fallen to, or have been seen very near, the earth; for while the majority (see the museums of Vienna, St Petersburg, and London) measure only a few inches, with occasional masses of 2 and 3 feet, there was one unusually well observed by many able spectators in Scotland, England, and France, on the 18th August 1783, which was estimated to be more than half a mile in length.

Let us inquire, then, how far the known meteoric mass of 18th August 1783 would suffice to produce the effects observed on September 1st, 1859, had it then fallen to the sun. Professor W. Thomson gives the amount of meteoric matter that would be required, according to Mr Waterston, to produce, by striking the sun, the average solar illumination, as 0.000060 lb. per square foot per second.

For the period of our phenomenon, or 5 minutes, this is 018 lb. per square foot, and 501·811 lb. per square mile for the same time. Now the meteor in question, said by Mr Cavalho to have had a diameter of 1070 yards, can hardly have contained less than 15,000,000,000 cubic feet; and if we take for its specific gravity a mean between what has been determined by many measures of earthy meteorites on one hand, and meteoric iron on the other (which comes extremely near the mean density of the earth), then

the total weight must have been 5,250,000,000,000 lb. Whence it is evident that there was enough material in that one meteor, properly distributed, to keep a space 5,000,000 square miles of the sun's surface in a state of luminous ignition, twice as intense as that of the ordinary solar disc during all the time of observation; and therefore, by the transparency of flame, to have tripled the brightness of the parts passed over-a phenomenon which, from angular subtense, as well as intensity of light, would be abundantly visible to telescopic observation from our earth.

On the whole, then, it appears exceedingly probable that the solar phenomenon of September 1st was a meteor falling to the sun, and giving out the heat of its mechanical energy in accordance with the laws of that dynamical theory of thermotics, first and chiefly in this country brought before the Royal Society of Edinburgh by Professors W. Thomson and Macquorn Rankine. In which case, there is another example added, to several that might be extracted from the history of science, showing that hardly has a true theory been published to the world, before a confirmatory phenomenon, previously quite unexpected, is almost providentially witnessed; and in no case by less prejudiced or more able observers than the gentlemen upon whom we depend in the present instance.

2. On the Fallacy of the Present Mode of Estimating the Mean Temperature in England. By James Stark, M.D. (This paper appears in the present number of this Journal.)

3. Description of the Plant which produces the Ordeal Bean of Calabar. By Professor Balfour.

After noticing the various plants used in Africa as ordeal poisons, the author gave an account of the introduction of the Calabar Ordeal Bean into Scotland, by the Rev. W. Waddell, and mentioned its peculiar poisonous qualities, as determined by Dr Christison. To Dr Hewan, and the Rev. Zerub Baillie, who are connected with the United Presbyterian Mission in Old Calabar, he was indebted for some observations on actual cases of poisoning in Africa. The Rev. W. C. Thomson, another missionary, was the first who procured flowering specimens of the plant. Some of these had been given to the author by Mr Baillie, and from them, along with the legume and seeds, the characters of the plant had been drawn up. The plant belongs to the natural order Leguminosa, sub-order Papilionaceæ, and tribe Phaseoleæ, and appears to be a new genus to which the name of Physostigma (ovodew, to inflate) has been given, from the peculiar inflated appearance of the stigma. To the species the name of venenosum has been given, in allusion to its poisonous qualities. The genus is nearly allied to Phaseolus, from which it differs

in the stigma, and in the long, grooved hilum of the seed. In the last character it approaches Mucuna.

Physostigma venenosum is a large twining plant, with a thick stem, and pinnately-trifoliolate leaves. The inflorescence is nodosoracemose, the flowers being curved, and of a pale pink colour, the stamens 10, diadelphous, the style bearded at its upper part, and the stigma covered with a remarkable crescentic ventricular sac. The legume is 7 inches long, of a brown colour, containing two or three dark-brown seeds, with a long, deep hilum.

The paper was illustrated by drawings, executed by Dr Greville.

Botanical Society of Edinburgh.

Thursday, 8th December 1859.-Professor BALFOUR, V.P., in the Chair. The following Communications were read:

1. On the Anaesthetic Effects of Chloroform, Ether, and Amylene, on Sensitive Plants. By JOHN S. LIVINGSTON, Esq.

After explaining the method employed in performing the experiments, Mr Livingston proceeded to detail such of them as were of a typical character.

The anaesthetic influence it was found proceeded from leaf to leaf invariably in the descending order, and it very rarely happened that the leaf above the one acted on was at all disturbed. This effect was first observed by Professor Marcet of Geneva, and communicated by him in a paper to the Société de Physique. To whatever source this singular phenomenon might ultimately be traced, whether to a susceptibility of the descending sap for transmitting narcotic effects, or to the existence of some yet undiscovered organ which had that power, the fact was, at all events, beyond dispute.

To set aside any source of fallacy, and subject this fact to as severe a test as possible, the rootlets of the sensitive plant (Mimosa pudica), were carefully exposed, and doses of chloroform, ether, and amylene given, in order to see whether it was not possible in this way to induce a propagation of the influence upwards. In every case in which any effect was exhibited, it invariably proceeded downwards. When ether and amylene were employed, no effect, it is true, was produced; but in the case of chloroform, instead of the narcotic influence attacking first the leaf nearest the roots, as one would expect à priori, it passed by four of the leaves, and appearing first at the fifth, proceeded downwards till the first was reached.

De Candolle, in his "Physiologie Vegetale" (ii. p. 866), mentions some experiments made by him with sulphuric and nitric acids, on a sensitive plant, by which it was shown that these acids cause a folding of the leaves and a dropping of the petioles in an ascending order. These experiments had been repeated, and found substantially correct. A drop of sulphuric or nitric acid when placed on the lowermost petiole caused all the leafstalks to fall much below a right angle.

Of the three anæsthetic agents employed, amylene was found, on the whole, to act most powerfully on sensitive plants. With it the petioles always dropped down to more than a right angle with the stem, while with chloroform that was rarely the case. With both, the petioles NEW SERIES.-VOL. XI. NO. II.-APRIL 1860.

2 s