The specimen was cut across in the centre when portions of the incrustation were detached; by this means the structure of the specimen, and the nature of the substances forming the incrustation, could be well observed. The substances were generally found to occur in the following order, from within outwards.
I.—Solid metal.
II.—Particles of metal resembling filings, tarnished on the surface, and intermixed more or less with a dull greenish-grey substance, which was found to contain chlorine, copper, and tin.
III.—A pale green dull soft compact layer, which was found to consist chiefly of carbonate of copper, containing chlorine, probably in combination as oxychloride of copper, and a little peroxide of tin.
IV.—Red oxide of copper, varying in colour from brick-red to dark red, compact, dull and opaque, and in part crystalline.
V.—Peroxide of tin: examined under the microscope it was found to be veined with minute thin layers of red oxide of copper.
VI.—Red oxide of copper similar in character to No. IV.
VII.—Irregular patches of amorphous and crystalline substances of various shades of green, blue, and brown, as before described.
The above order of superposition was not always observed; thus, in some places there was a layer of red oxide of copper in No. III.
When the incrustation had been removed by sawing the specimen across the middle, and filing, the metal was found to be very sound and free from cavities. The fracture was yellowish copper red, and finely granular.
Portions of the solid metal perfectly free from incrustation were selected for analysis.
COMPOSITION PER CENT.
| I. | II. | Mean. | |
|---|---|---|---|
| Copper | 86·41 | 86·31 | 86·36 |
| Tin | 13·05 | 13·07 | 13·06 |
| Lead | — | 0·11 | 0·11 |
| Iron | 0·17 | — | 0·17 |
| Nickel | 0·15 | — | 0·15 |
| Cobalt | traces | — | traces |
| 99·85 |
The specific gravity of the metal was 8·858 at 60° Fahr.
A portion of clean solid metal weighing 24·811 grains was employed for the experiment.
The substances forming the incrustation could not possibly be separated from each other with sufficient accuracy to allow of their being separately analysed.