To the professional zeal and liberality of my lamented friend Dr Adam, late Secretary to the Medical Board at Calcutta, I am indebted for many interesting specimens of the Materia Medica of Hindostan. Among these was a large supply of the powder of the bark of the Mudar or Mudhar, the Calotropis Mudarii of Dr Hamilton, which, with a nearly allied species, had been formerly referred to the genus Asclepias, under the trivial name of gigantea.

The high reputation which the Mudar Powder enjoyed among the natives of India, as a specific for the cure of various cutaneous diseases, induced Mr Playfair, Mr Robinson, and Dr Vos, to investigate its action as a medicine. These gentlemen gave favourable reports of its effects in India, in cutaneous diseases, syphilitic affections, and tape-worm.

The sandstone quarry of Corncockle Muir is situated between the rivers Annan and Kinnel, about a mile and half above their confluence, and not quite three miles from the town of Lochmaben in Dumfriesshire. It is near the top of a low, round-backed hill, which stretches about half a mile in a westerly direction, almost in the line of the rivers. This hill rises out of a valley of irregular surface, terminated, at the distance of some miles, on the north and north-west, by a mountainous range of transition rock; on the south by an arm of the same range; and on the east, at a greater distance, by lower elevations, consisting, according to Professor Jameson, partly of floetz-trap and partly of the independent coal-formation. The valley itself is said by the same authority to be of the independent coal-formation, lying on the transition rock, and contains considerable quantities of sandstone interspersed in various parts, and stretching as far as the bottom of the mountains.

1. Anhydrous Silicate of Iron.

This mineral was given me for examination by Patrick Doran, an Irish mineral-dealer, who discovered it in Slavcorrach, one of the Morne Mountains, on the north-east coast of Ireland, forming so conspicuous an object at the southern extremity of the county of Down.

The colour is dark brown, with something of the metallic lustre.

The mineral is foliated, and breaks easily into four-sided prisms, seemingly right; though the summits are very obscure.

The fragments are strongly attracted by the magnet, but they have no poles.

It has been long known that the Prussian blue of commerce contains an admixture, in greater or less quantity, of alumina, sulphate of potash, and common alum, one or all of them being easily detected in every specimen. The sulphate of potash and the alum may be separated by frequent boiling in water, but they are seldom in such quantity as to render this process necessary. The alumina may be removed by digestion in muriatic acid, and the washing consequent upon this mode of treatment will free it from all the soluble impurities.

When the alkalies or earths are digested with Prussian blue, in order to form the common Prussiates, and the yellow solution is evaporated, it almost uniformly happens that after the first or second crop of crystals is separated, there remains a dark brownish-red liquid, which either does not crystallize at all, or gives crystals of the required prussiate of a dirty brown colour, and mixed with a greater or less portion of a red matter, either massive, or in small, red, four-sided needles and prisms. This may be observed in preparing the prussiates of lime or soda by the common process, but has been more frequently taken notice of in forming the cyanide of mercury; because the least colouring matter in this salt is at once perceptible, and because in the preparation of it, a partial loss is of greater consequence. To the presence of a portion of this red salt, particularly in extemporaneous prussiates, I attribute those differences in the colour of the precipitates which they give with the metallic oxides, and which have led some to doubt the accuracy of their indications. The grounds of this opinion will appear in the sequel of the present paper.

When in London in spring last year, Mr Parish had the kindness to show me some specimens which he had just received from his son, Mr Woodbine Parish, his Majesty's Consul-General at Buenos Ayres, among which I was surprised and much pleased to find two masses of native iron, exactly similar to the celebrated Siberian block, made known to the scientific world through the exertions of Pallas, having the same vesicular structure, and containing the same straw-yellow coloured olivine firmly imbedded.

I immediately suggested to Mr Parish the propriety of losing no time in making this discovery known, and thereby secure to his son the merit of bringing it before the public; and in order to do this in the most effectual manner, I advised him to present one of the masses to the Royal Society of London, and the other to the Royal Society of Edinburgh; and it is with pleasure that I now find myself deputed to carry his wishes with respect to this Society into execution, by presenting one of the masses as a donation to this institution in the name of his son.

The facts and observations I have now the honour to bring before the Society, were fully made out, and their general correctness ascertained, somewhat more than three years ago. Since that time I have been in the habit of alluding to them, and demonstrating the strictly anatomical part, in my summer course of lectures on comparative anatomy; so that, in short, they may be considered as having, to a certain extent, undergone the ordeal of public opinion. I have thought it right to mention this circumstance, inasmuch as the statements and opinions to be brought forward this evening are contradictory of others which have been promulgated by some anatomists of high standing, and have been received and admitted by naturalists, and by the non-professional, as observations not to be doubted nor controverted; as matters of fact which call for no deeper inquiry; as statements on which unerring doctrinal points might be founded.

The fruit in this natural order does not appear to have been well understood by most botanists; and I shall therefore attempt to give a general view of what appears to me to be its structure; and most of the parts are visible in the section which is here given (Plate IX. Fig. 1.) of the beautiful but insipid Indian Melon (Cucumis Melo) called Phuti.

The outer parietes (Fig. 1. a,) when young, are thick, fleshy, and undivided by sutures, with an uniform rind, not separable from the fleshy part. As the fruit ripens, the rind in some cases becomes so thin as to be unable to contain the pulpy matter, and bursts either gradually, as in the melon, or with elasticity as in the Momordica and Elaterium of Tournefort. At other times, the rind hardens either into a thin substance like leather or strong paper, as in the Luffa, or into a strong ligneous covering, as in the Cucurbita leucanthema or gourd. In these cases, it sometimes opens horizontally, by means of an operculum, which falls off and leaves an aperture for the seeds, as in Fig. 2. representing the summit of the Luffa called Picinna in the Hortus Malabaricus.