VI.—FRAGMENT OF A COPPER KETTLE.

FROM THE FOURTH SEPULCHRE.

This specimen was in a single piece, much crumpled, irregular in shape, and ragged at the edges; it weighed about 800 grains, and varied from 1-25th to 1-30th of an inch in thickness. There were three rivets in the metal, the ends of which protruded on one side to the extent of about 1-8th of an inch; and there was one rivet-hole without its rivet. After filing, the colour of the metal forming the rivet appeared to be the same as that of the sheet metal. There was no trace of the article which had been attached by means of those rivets. On one surface the specimen seems originally to have been pretty generally encrusted with blue and green matter, between which and the metal was, as usual, a thin coating of red oxide of copper; on the other surface, or that showing the protruding ends of the rivets, the metal was coated first with the red oxide of copper and then with dark greenish brown matter, with here and there patches varying from light green to dark blue and dark green, especially round the ends of the rivets.

Portions of the sheet metal were heated to redness in a current of hydrogen, whereby they acquired a coppery colour and lustre. The water evolved in this process was found to contain both copper and chlorine, thus indicating the existence of oxychloride of copper in the incrusting matter, a portion of the subchloride of copper (cuprous chloride) having escaped decomposition by the hydrogen. A piece of the metal, free from incrustation, was boiled in a flask containing hydrochloric acid and perchloride of iron, and the vapour evolved was passed into a refrigerating vessel, when a liquid was obtained in which arsenic was found in considerable quantity. This process was used for the quantitative determination of the arsenic as ammoniacal arseniate of magnesia, and the result was confirmed by several repetitions. The metal taken for analysis was that which had been heated in hydrogen as stated above. The analysis was made in the laboratory of the Royal School of Mines by Mr. W. F. Ward.

COMPOSITION PER CENT.

Copper98·47
Tin0·09
Lead0·16
Bismuth traces
Silver0·013
Iron0·03
Nickel0·19
Arsenic0·83
99·783

INDEX.