130
BURNING MIRRORS.
Different Substances fused.
Gold, pure .
Silver, ditto.
Copper, ditto .
Nickel.
Bar iron, a cube.
Cast iron, a cube.
Steel, a cube .
Scoria of wrought iron .
Kearsh.
Cauk, or terra ponderosa • •• •
An Orientalemerald .
Crystal pebble.
Flint, Oriental.
Rough cornelian.
Jasper...
Garnet.
Zeolite.
White rhofnboidal spar .
Rotten stone .
Common slate.
Asbestos .
Common lime-stone.
Pumice-stone .
Lava.
Volcanic clay .
Cornish moor-stone.
Weight
Time ®f Fusion,
in Grains.
Seconds.
16 . 3
3 . 45
10 . 75
.... 20
.... 17
- * 10 * -
.... *>
10 . 24
Mr. Parker also gave information, that a diamond,weighing 10 grains, exposed to this lens for 30 minutes,was reduced to 6 grains ; during which operation it openedand foliated like the leaves of a flower, emitting whitefumes, and when closed again, it bore a polish and retainedits form. Mr. Parker, jun. also furnished the followingobservations upon the uncommon power of this lens. Goldremained in its metallic state without apparent diminution,notwithstanding an exposure at intervals of many hours,but the rest, or eassel, which was composed of bone-ash, wastinctured with a beautiful pink colour.
Platina. —The experiments evince that the specimenswere in different states of approach to a metallic form;several of them threw off spaiks, which in most instanceswere metallic.