The author commenced by stating, that he had repeated the greater part of the analysis of hemlock lately executed by Professor Geiger of Heidelberg, and had obtained precisely the same results. According to his analysis, hemlock contains a peculiar principle, alkaloidal in its nature, but differing from the previously discovered alkaloids in its form, which is that of an oily-like liquid, volatile at a moderate elevation of temperature, and capable of being readily distilled over with water. It neutralizes acids, without however forming crystallizable salts. It contains a considerable proportion of azote. It quickly undergoes decomposition when exposed to the air, giving out ammonia, and becoming a dark, resin-ous-like substance.

The first part of this paper (which accompanied a series of geological specimens from Auvergne, presented to the Society) relates to several specific points which tend to assimilate the evidence for the igneous origin of trap-rocks generally, with that afforded by the volcanic district of Central France. The altered character of the stratified deposits with which igneous rocks have been intermixed, is one of their most striking features; yet we occasionally find cases where this evidence is far from being so obvious as might be expected; and this dubious character, which is particularly remarked in the hill of Gergovia, near Clermont, forms an admirable parallel to some cases in trap districts where a like want of alteration occurs.

This substance, obtained among the products of the reaction of chloride of sulphur on a solution of ammonia, is a solid, colourless, insoluble in water, soluble in alcohol, crystallizing in cubes. It is characterized by producing a fine, but fugitive purple colour, when brought into contact with potash and alcohol.

Dr Gregory obtained from it between 92 and 93 per cent. of sulphur, and from 6 to 7 per cent. of nitrogen.

Dr Davy communicates the description of certain streams of seawater which appear to be constantly flowing into the interior of the earth, by four openings, near the town of Argostoli, in Cephalonia. These are now applied as sources of mechanical power. Dr Davy views this curious fact as probably related to the very remarkable local earthquakes which affect the Ionian Islands, and which appear to be disconnected with any volcanic appearances, or even the occurrence of trap-rocks. Dr Davy conceives that these phenomena may be attributable to the absorption of this quantity of sea-water constantly received into the land by the marly beds which occur in Cephalonia.

This paper, tending to establish the chemical action of atmospherical electricity, is based upon experiments made in Malta between October 1834 and March 1835. The mode of operating was the following: A tube of glass containing a wire of copper was elevated six feet in all above a turret in Dr Davy's house in Valletta, which rose just fifty feet from the street. It was not in the highest part of the town, and was overtopped by other buildings. To the lower part of the copper-wire was attached one of gold. The communication to the ground was effected through the medium of another copperwire, connected with a leaden cistern.

The object of the author in this paper was to find a new method of avoiding Euclid's assumptions in the theory of parallel lines. This he endeavours to do by proving that lines making equal angles with a given line cannot recede from one another ; but he does not effect this without the introduction of the consideration of infinitely small spaces.

Professor Forbes shewed a specimen illustrative of the star-like fractures of horizontal strata, as assumed in the theory of Elevation Craters. It was a stratum of crystallized chloride of calcium, which had been accidentally fractured and elevated in Dr Christison's laboratory by the sudden disengagement of steam beneath during crystallization.

The author commenced, by stating the general proofs of the knowledge of the principles of equilibrium displayed by Gothic architects in the structures (especially) of the pointed style. The adaptation of their edifices was to the combined ends of elegance and strength. The extension of this principle to the case of the Gothic pendant is the chief object of this paper. Sufficiency in point of strength, without redundancy of material, is considered by the author as the primary source of architectural beauty; which he has demonstrated to be the case when the depending Gothic drop is generated by the revolution of the logarithmic curve round its axis.

In a fragment of this kind of coal there was accidentally found a very fine specimen of a tooth, which the author considers to belong to the Megalichthys Hibberti of Agassiz. It is similar to some of those found in the limestone of Burdiehouse by Dr Hibbert, and is almost identical with that figured at p. 183 in Dr Hibbert's Memoir, in the 13th volume of the Society's Transactions; being about two inches long, and seven-eighths of an inch at the base, longitudinally striated, and covered with a shining enamel.

The prize founded by our late estimable associate Mr Keith, whose ingenious contrivances for self-registering thermometers and barometers are recorded in our Transactions, is, by the regulation of his Trustees, to be adjudged biennially for the most important discovery communicated to the Royal Society, or in the event of such being wanting, for the best paper which shall have been presented to the Society in the space of two years on a scientific subject. The Council, in discharge of the powers vested in them, have awarded unanimously the Keith prize for the last biennial period, to Professor Forbes, for his paper "On the Refraction and Polarization of Heat,” which they consider to come under that class of communications, which contain discoveries important to science.

The line of argument went to shew, that the Umbri were one of the most ancient nations of Italy. That they, through their colonies or entire tribes, entered deeply into the composition of the primitive population of Rome. That, according to ancient authorities, these Umbri were the descendants of the “Veteres Galli.” That these Veteres Galli were of the same race and blood as the present Cumbri of Wales, Cornwall, and Brittany. That hence it is probable, that the ancient language still preserved among these may have entered easily into the composition of the language of the Romans.

Gamboge was first made known by Clusius about the commencement of the seventeenth century, as a concrete juice from China. About the middle of the same century, Bontius conceived he had traced it to a particular species of Euphorbia, growing in Java and in Siam; from the latter of which countries the whole gamboge of commerce was at that time obtained. About the close of that century Hermann announced that gamboge was produced by two species of trees growing in Ceylon, which have been since often confounded together, but which are now designated by the names Garcinia Gambogia, and Stalagmitis Gambogioides. About the middle of last century, gamboge was referred by Linnæus to the former of these plants, and his reference was generally admitted. But about thirty years later, Professor Murray of Göttingen conceived he had traced it satisfactorily from the specimens collected by Koenig in Ceylon, and information obtained by the same botanist in Siam, to a new species which he called Stalagmitis gambogioides.

After premising some general remarks respecting the object of research, and enumerating the various authors who had written upon the subject, Dr Hope explained various terms which were to be used in the discourse. To the various coloured matters presented by the leaves and flowers of plants, De Candolle had applied the denomination of Chromule, which term he meant to adopt.

There resides in the same parts of plants, in addition to the chromule, some matter probably destitute of colour, which becomes red by the action of acids, and yellow or green by the action of alkalies. To it Mr Ellis gave the name of colourable matter, which the author changes to Chromogen, When an acid, added to a vegetable infusion, causes a red colour, and an alkali a yellow or green, it has been the universal opinion that both sets of agents act upon one and the same colourable principle.

Thirst and loss of appetite were the first symptoms experienced by Dr Barry at a height of about 14,000 feet; but it was not till he reached a height 1000 feet greater, that exhaustion and fatigue supervened. A tendency to fainting was felt, and a total indifference to the main object of the journey. After a few minutes of rest, these sensations disappeared, but were again perceived on proceeding a few steps. On the summit (15,666 feet above the sea; Barom. 17.052, Detached Therm. 30°) no particular lassitude was felt while the author performed his experiments. After the descent the author did not suffer from a state of collapse.

“I have recently ascertained the following facts respecting heat.

“1st, That heat polarized in any plane, and then reflected from the surface of a refracting medium, changes its plane of polarization in a manner similar to what obtains in the case of light. Thus, with a thick plate of mica, which polarized homogeneous red light most completely at an incidence of about 59°, the plane of polarization of reflected polarized heat remained on the same side of the plane of reflection when the incidence was great, and was on the contrary side when the incidence was small. The limiting angle of incidence was about 57°, which therefore should be the polarizing angle of dark heat for mica. This mode of observing the polarizing angle offers some advantages above more direct methods.