1816.] Scientific Intelligences 321 
would be broken by a weight of 25°6 tons. This is considerably less 
than the strength of iron resulting from Sickingen’s experiments... 
He found that an iron wire 0°078 of an inch in diameter was broken 
by a weight of 549-25 lbs. avoirdupois. Now if we suppose the 
strength of iron wire to vary as the squares of its diameter, the pre- 
ceding experiment will give us the weight capable of breaking an 
iron wire of the diameter 0:078 of an inch 348°SS lbs. avoirdupois. 
Hence, supposing both experiments correct, English iron must be 
materially weaker than Swedish iron. 
IX. New Ore of Copper. 
Mr. Mawe, mineral dealer in the Strand, received some time 
ago a cargo of minerals trom Cadiz, which had been shipped origi- 
nally at Vera Cruz, and of course are the produce of Mexico. 
Among them ‘there were a few specimens of a copper ore, which, to 
me at least, was new; nor have I been able to find any allusion to 
it in any of the mineralogical books which I have consulted. The - 
specimens which I have seen being few and small, the following 
description will be imperfect :— ; 
Colour, verdigris-green, with a tint of blue. The central parts 
of the distinct concretions appear darker coloured than towards the 
circumference, owing, I conceive, to the translucency of the edges 
of these concretions. Some few of the concretions are coated with 
a whitish crust, but this is uncommon. ; 
Most of the specimens had a botryoidal form; one of them was 
thin, as if it had constituted a portion of a thin vein. 
Lustre, vitreous, and varying much in intensity. The internal 
lustre of a distinct concretion fully as strong as that of glass ;- but 
the external lustre is often dull. 
Fracture compact, conchoidal. Fragments somewhat rounded 
with blunt edges. In granular distinct concretions rather larger 
each than a grain of mustard seed. ‘Translucent on the edges. 
Nearly as hard as calcareous spar. It is readily scratched by a knife. 
The distinct concretions are very easily separated from each other; 
but a single concretion is not more easily frangible than alum or 
rock salt. Brittle. Specific gravity 2°238. 
When a distinct concretion is thrown into nitric acid, no effer- 
vescence takes place; but if we reduce the mineral to powder, it 
effervesces in that acid, and is partly dissolved. The same solution 
takes place in the course of a few days if a lump of the mineral be 
put into nitric acid. A white insoluble powder remains, which 
fuses into a glass with potash, and is therefore silica. The nitric 
acid solution is blue, but becomes green when mixed with muriatic 
acid, %4*1 grains of the mineral treated in this way furnished 6°1 
graius of silica; and the copper, being thrown down by a plate of 
zinc, weighed 10°5 grains. Now 105 grains of copper constitute 
14 125 grains of peroxide of copper. ‘This oxide in the ore was 
united to carbonic acid and carboncte of copper, as 1 have ascer- 
tained by experiment, and is composed of one atom acid and one atom 
