--------------------------------------+-------+-------+ Substances melted, with their weight; |Weight | Time | and the Time in Seconds, which | in | in | they took in melting. |Grains.|Seconds| --------------------------------------+-------+-------+ Pure gold | 20 | 4 | ---- silver | 20 | 3 | ---- copper | 33 | 20 | ---- platina | 10 | 3 | Nickel | 16 | 3 | A cube of bar-iron | 10 | 12 | --------- cast-iron | 10 | 3 | --------- steel | 10 | 12 | Scoria of wrought-iron | 12 | 2 | Kearsh | 10 | 3 | Cauk, or terra ponderosa | 10 | 7 | A topaz, or chrysolite | 3 | 45 | An oriental emerald | 2 | 25 | Crystal pebble | 7 | 6 | White agate | 10 | 30 | Oriental flint | 10 | 30 | Rough cornelian | 10 | 75 | Jasper | 10 | 25 | Onyx | 10 | 20 | Garnet | 10 | 17 | White rhomboidal spar | 10 | 60 | Zeolites | 10 | 23 | Rotten-stone | 10 | 80 | Common slate | 10 | 2 | Asbestos | 10 | 10 | Common lime-stone | 10 | 55 | Pumice-stone | 10 | 24 | Lava | 10 | 7 | Volcanic clay | 10 | 60 | Cornish moor-stone | 10 | 60 | --------------------------------------+-------+-------+ _Fulminating Powder._ This powder is made by rubbing together, in a hot marble mortar, with a wooden pestle, three parts, by weight, of nitre, two of mild vegetable alkali, and one of flowers of sulphur, till the whole is accurately mixed. If a drachm of this powder be exposed to a gentle heat, in an iron ladle, till it melts, it will explode with a noise as loud as the report of a cannon. _A more powerful fulminating Powder._ The most wonderful instance of chemical detonation is formed by the combination of volatile alkali with silver. Gunpowder, or fulminating gold, are not to be compared with this invention, and the great danger attending its manufacture prevents us from giving a methodical account of its preparation to our readers, particularly as it can be purchased, properly prepared, of the chemists.