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surface appeared in some parts uneven : the prominencieslooked bright and polished; the cavities dark colouredand roughiih, as if they were sprinkled with a powderymatter. A few of the grains were attracted, though veryweakly, by a magnetic bar.

II. Subjlances mixed with the native platina.

With the grains of platina, above described, severalheterogeneous matters are intermingled ; some of whichare in small particles or dust, separable by a fine sieve;others larger, so as to be distinguished by the eye andpicked out. These substances, in the different parcels ofplatina which I examined, were the following.

1. A considerable quantity of blackish dust, which ap-peared to consist of two dissimilar substances ; a part of itbeing attracted vigorously by a magnetic bar, and a partnot attracted at all. The part attracted is of a deepsparkling black colour, much resembling the black sandfrom Virginia : the rest is of a brownish hue, and hasseveral bright particles intermixed, which appear to befragments of the grains of platina itself. It is probablethat the roughness and dark colour of the cavities of thegrains of platina, and the magnetic quality of some c.tthe grains, proceed from some portion of these extraneouspowders adhering in them.

2. Among the larger grains of platina, separated by

means of a coarse sieve, were observed sundry irregular

darb-coloured particles, some blacklist, others with a cast

of brownish-red, in appearance resembling fragments of

emery or loadstone. Some of these were attracted by the

magnet, very weakly, and others not at all. The un-

anagnetic dust of the preceding paragraph seems to be

only smaller fragments of this last kind of matter.

7. There

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