"The advantage of being able to purify and proportion, in some measure, the principles of the gas which feeds the flame is," said M. LEBON, "set forth in the clearest manner. But this flame is so subjected to our caprice, that even to tranquilize the imagination, it suffers itself to be confined in a crystal globe, which is never tarnished, and thus presents a filter pervious to light and heat. A part of the tube that conducts the inflammable air, carries off, out of doors, the produce of this combustion, which, nevertheless, according to the experiments of modern chymists, can scarcely be any thing more than an aqueous vapour. "Who cannot but be fond of having recourse to a flame so subservient? It will dress your victuals, which, as well as your cooks, will not be exposed to the vapour of charcoal; it will warm again those dishes on your table; dry your linen; heat your oven, and the water for your baths or your washing, with every economical advantage that can be wished. No moist or black vapours; no ashes, no breaze, to make a dirt, or oppose the communication of heat; no useless loss of caloric; you may, by shutting an opening, which is no longer necessary for placing the wood in your oven, compress and coerce the torrents of heat that were escaping from it. "It may easily be conceived, that an inflammable principle so docile and so active may be made to yield the most magnificent illuminations. Streams of fire finely drawn out, the duration, colour, and form of which may be varied at pleasure, the motion of suns and turning-columns, must produce an effect no less agreeable than brilliant." Indeed, this effect was exhibited on the garden façade of M. LEBON'S residence. "Wood," concluded he, "yields in condensable vapours two thirds of its weight; those vapours may therefore be employed to produce the effects of our steam-engines, and it is needless to borrow this succour from foreign water." _P. S._. On the 1st of last Vendémiaire, (23rd of September), the government presented to the Chief Consul a sword, whose hilt was adorned with fourteen diamonds, the largest of which, called the _Regent_, from its having been purchased by the Duke of Orleans, when Regent, weighs 184 carats. This is the celebrated _Pitt_ diamond, of which we have heard so much: but its weight is exceeded by that of the diamond purchased by the late empress of Russia, which weighs 194 carats; not to speak of the more famous diamond, in possession of the Great Mogul, which is said to weigh 280 carats. LETTER V. _Paris, October 24, 1801._ Last night I received yours of the 20th ult. and as Mr. M----y purposes to send off a dispatch this morning, and will do me the favour to forward this, with my former letters, I hasten to write you a few lines.