It was with considerable reluctance that I felt myself compelled to discard the system of coloration adopted in the Geological Survey Maps; and rids I did only after the strongly expressed opinion of several geologists.

It was not that I have any very intense desire to colour rocks after their natural tints, but I have an aversion to adopting a colour suite which departs markedly therefrom; or one which is in discordance instead of harmony therewith. One friend, a man of great scientific discretion, and himself an artist, writes me that when he looks at a recently published geological Map of Scotland, with its grey Torridon and its red Laurentian, he does not know whether he is standing on his head or his heels.

While making some experiments with a form of miner's lamp, which has recently been introduced for the purpose of burning soft paraffin wax in place of tallow, it occurred to me that this wax, which melts at about 38°C would be a very suitable fuel for a portable blowpipe lamp, being both cheap and cleanly. Having thus got a suitable fuel, the next step was to devise a lamp to burn it, and afar one or two trials the form shown in the annexed sketches was adopted.

The granite of the Ord forms one, and that probably the smallest of a number of masses which constitute the border-land between Caithness and Sutherland. The features of this granite vary considerably at different points. It will, however, be afterwards shown that the rock is possibly continuous from north to south,--that is, from Sandsidc Bay, on the Pentland Firth, to Navidale, near Helmsdale.

Since my last communication on Artificial crystals (Min. Mag. No. 19), I have met with some very remarkable crystals formed in a Copper Works Slag which consisted mainly of Cuprous Oxide and Ferric Oxide with a little lime, a product from melting a charge of “copper precipitate.”

The crystals are hexagonal plates, bounded on the edges by the faces of a rhombohedron which roughly measured gives an angle of R : R=86° They arc iron black in color, with a splendent metallic lustre, and contain 50% Ferric Oxide with 45% copper.

Examined under the microscope or even with a strong lens, particles of copper and cuprous oxide are visible in a separate state.

The following are chiefly notes of a longer paper read April 5th, 1882, before the Société Vaudoise des Sciences Naturelles.

For some years familiar with the valleys of Anniviers, St. Nieklaus, Zermatt and Saas, the author has made a study of comparison between the above rocks in situ and erratic specimens of the same nature. The want of a laboratory and of more than a travelling microscope with polarising apparatus render his researches so imperfect that a more complete report upon these rocks must be deferred.

The accompanying engraving represents an exceptionally fine group of crystals ofapatite, found in the Untersulzbachthal in Salzburg. The dimensions are those of the original, its colour is white with a delicate tint of mauve. This group is the finest of three of the most magnificent specimens yet found at this or any other locality, the largest one having been deposited in the national collection of minerals at South Kensington, while the third was unfortunately broken.