The localities of geognostic interest in this large island have been referred to in the general description of the islands, and its mineralogy alone now remains to be considered.

It has been remarked above, that the muddy silts which, impregnated with the putrescent pitch of fermenting organisms, form the great mass of the flags of the “Old Red,” are exceptionally barren in minerals of interest. The cauce of this is not far to seek :—the components of such silts are not themselves those which go to the formation of many mineral bodies ;—nor have they been subjected to the metamorphic stimulus which excites to a chemical union of ingredients and elements which lie merely in the contact of granular apposition.

It has often struck me that much more might be learned from the study of the secondary forms of crystalline minerals than we now know respecting the circumstances under which they were produced. Some years ago being chiefly acquainted with calcite as it occurs in Derbyshire, where the crystals are usually of the so-called dog-tooth shape, my attention was much attracted by the difference in the form of the crystals in Devonshire and Cornwall, where we so often meet with six-sided prisms. On reflecting on this difference I could not give any more satisfactory explanation than that the conditions under which they were formed must have been very different in some important particular. Various experiments, made both before and afterwards, sufficed to indicate at all events some of the possible causes of such a difference in the form of this mineral, but at the same time showed clearly that much special research would be required before we could draw such definite conclusions as could be desired.

In a letter to Dr. Heddle, Capt. Marshall Hall writes—" On the next page I give you, in complement of my last letter, the analysis of a serpentine from the Saas Thal. For the specimen I am indebted to M. Henri de Saussure. It will be interesting to compare it on the spot, and study it in its relations to the accompanying rocks and minerals.

Whether the stone is fairly serpentine with so much iron is perhaps to be questioned ; I send the analysis as that of a "reputed " serpentine, and I send it to you as you have been doing serpentines, ... . as it is possible that additional data may be of use to you.

Jameson tells us that it took him six weeks to survey Orkney geologically, and that the journey was the most uninteresting he ever made ; his journal, indeed, is little more than a record of disappointments. Jameson's statement, so far from concealing, disclosed an indubitable fact, that to relieve the tedium of the hammer through weeks of wandering, some impulse,—some attraction of a different nature must be associated with it. Jameson himself showed that such attraction was present with him, though he seems to have put a restraint upon himself as regards the alluding to it.

As the rare descent of Meteorites or Aërolites affords us the only real tangible evidence we possess respecting the mineral constituents which exist beyond the limits of our own globe, a great degree of interest must always be attached to these stray visitors ; and although much has been written on the subject at different times, it has hitherto taken the form either of a bare catalogue of the date and place of occurrence ; or of scattered notices dealing only with individual cases. My desire is to collect these various records as far as they relate to each meteoric stone which has been known, or has been said to have fallen in Great Britain, and to endeavour to give as complete an account as possible of every instance; including not only the historical facts, but also notices Of mineralogical observations and references to authorities.

When we look at a collection of crystals we see that they can be divided into groups according to their symmetry. Thus, one group the members of which form the cubical system, have a symmetry in three directions at right angles to each other ; that is to say we shall find similarly arranged planes at the extremity of three properly chosen axes. In other groups the symmetry is not so perfect. Thus, in the tetragonal system we find that the symmetry in the direction of the principal axis is different to the symmetry in the direction of the lateral axes.

This is a mere fragment of gneissic rocks which is imbedded between the granite of Roeness and the igneous rock which lies to the east : but so different are these entrapped rocks from the ordinary gneiss of Shetland, and so violent a twist do they seem to have received athwart of their normal strike, that the enquiry rises-whence did this fragment come ?

A spectator looking west from the top of Ornsfield, gazes seaward upon a mere heap of ruins ; while, looking landward, he also sees little else,-so riven and twisted are the rocks by the intrusion of dykes of porphyry, and so shattered and toppling from the invasion of the sea.

Whilst staying at Sidmouth, in 1877, I discovered the occurrence of Celestine, Sulphate of Strontian, in cavities of Red Marl lined with crystals of Calcite, occurring in masses which had fallen from the cliff on to the shore, under the summit of Peak Hill. It appears in the form of crystals, occasionally one inch in length, which occur singly or in groups, presenting a tabular, prismato-tabular, or prismatic form,—in the latter case resembling the Barytes Crystals of Alston Moor,—and are either simple, or form compound aggregations of considerable size. In colour they are blue, wine-yellow, or of an olive-yellow hue, and as regards form, brilliancy, and transparency, surpass in beauty any examples of this mineral that I have hitherto seen. A series of the choicest specimens collected by me are exhibited in the Museum of Practical Geology, Jermyn Street.

The crystals referred to were found in considerable quantity in the slags produced in Mr. Hollwaf's experiments on the reduction of metallic sulphides at Penistone, in July 1878.

The experiments were carried out with ordinary Bessemer plant. Upon running the molten mass from the ladle into one of the ingot moulds the slag ran in a thick stream of perfect continuity, falling without noise a distance of some feet into the liquid portion below. The crystals occurred lining cavities in the partially cooled slag from which a portion of the molten material had been withdrawn.

The examination of the rhyolite exhumed by Dr. Henry Hicks, F.G.S., from the conglomerate of the Pebidian formation of St. Davids, Pembrokeshire (Quart. Journ. Geol. Soc., May., 1878, p. 153), recalled to my mind certain rocks from other localities which bad found a place in the large and important petrological collection in the British Museum, which I thought might prove to belong to the same group. Among these, some fragments brought from Bouley Bay, Jersey, by Wm. Carruthers, Esq., F.R.S., whose attention they attracted, interested me especially. It was found, however, that they had not been collected with the view of illustrating the rock in all its varieties, so further examination was postponed until an opportunity occurred to procure more material.

The behaviour of tin under varying circumstances has frequently attracted the attention of chemists, and several authors have concluded that it is capable of assuming at least two different crystallographic forms, only one of which, however, has been thoroughly investigated. Since Miller described the beautiful pyramidal crystals of tin obtained by galvanic deposition from a solution of its protochloride, the anomalous appearance of those obtained in the dry way has often been remarked upon. Brooke obtained octagonal needles on slowly cooling molten tin and pouring off the fluid part. Pajot in a similar manner obtained rhombic prisms. Stolba obtained quadratic plates, whilst Breithaupt saw tin crystals, from Cornish smelting furnaces, which had the form of short hexagonal prisms (Miller considered them to be Cu Sn2). Lastly Rammelsberg inferred from the varying specific gravity that a not yet determined dimorphic form existed.

At Mr. Collins's request I submit to the members of the Mineralogical Society the following preliminary notice of substances which I have collected during" my somewhat extensive wanderings about Scotland.

In the case of several of the substances described, it will be seen that I do not by any means bring them forward as being without doubt new minerals; of that, I have not satisfied myself, and still less can I hope to satisfy others, until specimens more fitted for absolute deterrmination are obtained, and that in a quantity larger than what I have as yet had to operate upon.

The noting and describing these substances now, will enable others to lend their aid in the work.

I have lately had the opportunity of conversing with one of our members, Mr. Jos. Jewell, who has been making an inspection of some parts of the island of Cyprus for mining purposes, and having been called upon by other parties to report on a number of mineral specimens brought from that island, I have thought that a short note on the subject might be of some interest to the members generally.

So much has been said of the mineral riches of the island, that I was astonished at the comparative poverty of the specimens brought home, and also at the very small number of mineral species which the island has so far yielded.

In my preliminary notice of this substance, I stated, upon the authority of Dr. Aitkin, that it had been supposed that it very possibly had at one time been used as a pigment in Inverness; a eolourist there manufacturing a paint the nature of which he kept secret.

In re-arranging lately, a number of chemicals which had been made over to me in 1856 by my predecessor, Mr. Connell, I found a bottle with a powder of the same tint, but somewhat darker than the washed Abriachanite. The label of this bottle bore on it "Ultramarine made in 1841, by Murdock Paterson, dyer in Inverness."

I have not yet had an opportunity of analysing this powder, which may be merely abriaehanite darkened by simple treatment with an acid.