humboldt's account of the gold and platina district of russia.

The following account is part of a letter from M. Humboldt to M.

Arago:--"We spent a month in visiting the gold mines of Borisovsk, the malachite mines of Goumeselevski and of Tagilsk, and the washings of gold and platinum.

We were astonished at the petitas (waterworn masses) of gold, from 2 to 3lbs., and even from 18 to 20lbs., found a few inches below the turf, where they had lain unknown for ages.

The position and probable origin of these alluvia, mixed generally with fragments of greenstone, chlorite slate, and serpentine, was one of the principal objects of this journey.

The gold annually procured from the washings amounts to 6,000 kil.

The discoveries beyond 59 deg. and 60 deg. latitude become very important.

We possess the teeth of fossil elephants enveloped in these alluvia of auriferous sand.

Their formation, consequent on local irruptions and on levellings, is, perhaps, even posterior to the destruction of the large animals.

The amber and the lignites, which we discovered on the eastern side of the Ural, are decidedly more ancient.

With the auriferous sand are found grains of cinnabar, native copper, ceylanites, garnets, little white zircons as brilliant as diamonds, anatase, alvite, &c. It is very remarkable, that in the middle and northern parts of the Ural, the platinum is found in abundance only on the western European side.

The rich gold-washings of the Demidov family, Nijnei-tagilsk, are on the Asiatic side, on the two acclivities of the Bartiraya, where the alluvium of Vilkni alone has already produced more than 2,800lbs. of gold.

"The platinum is found about a league to the east of the line of the separation of waters (which must not be confounded with the axis of the high summits,) on the European side, near the course of the Oulka, at Sukoi Visnin, and at Martian. M. Schvetsov, who had the good fortune to study under Berthier, and whose learning and activity have been most useful during our travels in the Ural, discovered chromate of iron, containing grains of platinum, which an able chemist at Catherineburgh, M. Helm, has analyzed.

The washings of platinum at Nijnei-Tagilsk are so rich, that 100 puds (about 400 lbs. Russian) of sand afford 30 (sometimes 50) solotniks of platinum, whilst the rich alluvia of gold at Vilkni, and other gold washings on the Asiatic side, do not give more than 11/2 to 2 solotniks in 100 puds of sand.

In South America, a very low chain of the Cordilleras, that of Cali, also separates the auriferous and non-platiniferous sands of the eastern declivity (Popayan,) from the sands of the isthmus of the Raspadura of Choco, which are very rich in platinum as well as gold. M. Bousingault may, perhaps, already have thrown a new light on this American formation, and his observations will derive some additional interest from those which we have made in this place.

We possess pepitas of platinum, of many inches in length, in which M. Rose has discovered beautiful groups of crystals of the metal.

"As to the greenstone porphyry of Laya, in which M. Engelhardt has observed little grains of platinum, we have examined it on the spot with much care, but the only metallic grains which we have been able to detect in the rocks of Laya, and in the greenstone of Mount Belayr-Gora, have appeared to M. Rose to be sulphuret of iron; this phenomenon will be a subject for new research.

The work of M.

Engelhardt on the Ural seemed to us to be worthy of much praise.

Osmium and irridium have also a particular locality, not amongst the rich platiniferous alluvia of Nijnei-Tagilsk, but near Belemboyevski and Kichtem. I insist upon the geognostical characters drawn from the metals which accompany the grains of platinum at Choco, Brazil, and in the Ural."

Edin.

Journal Nat. and Geog.

Science.