On our advertising page, will be found the advertisement of Mr. Newell's lamp, an in vention which we have examined and which we estimate highly. It is a scientific lamp, and one which no one not acquainted with chemistry, could' have invented ; because the improvement is founded upon a knowledge of the gases; it embraces the principle of Hum phrey Davy's invention of the Safety Lamp. In the centre of the lamp, extending to the bottom, is a fixed cylinder of fine tinned wire gauze, having a mesh of 500 to the inch. A tube of like gauze screws on to the wick disc, and confines the wick > this tube slips down inside of the gauze cylinder spoken 01. The can for containing the camphene, or turpentine and alcoholic mixture, which is now common ly used for lamps, is made with a disc of this wire-gauze in the spout and under the lid. We have seen the fluid in the lamp set on fire by taking out the wick, and the fluid set on fire at the spout of the can, and no explosion take place. We have also seen the fluid poured' into the lamp, out of the can, while the fluid in the spout and that in the lamp were bla zing, and, instead of an explosion, the flame was extinguished. It may well be asked, —how can this simple application of wire- gauze prevent explosions in fluid lamps 1 The question is an important one. It was discover ed by Humphrey Davy, that fine wire-gauze surrounding the flame of a lamp, wouh pre vent the ignition ofan explosive gas surround ing the lamp—but why it should do so men differ in opinion—the fact is know:!, and Mr. Newell has ingeniously applied his knowledge of the same. The reason why an] gas is ex plosive, that is, goes off like gunpowder, by sudden expansion and contraction, when igni ted, is owing to the combustible materials of its composition being fully saturated with ox ygen, and it is then in a fit state to ignite in stantaneously by the first spark. The gas we employ for lighting our streets, if it were sa turated with oxygen, woqld, when a burner was opened and touched with a match, ignite quick as the lightning flash all the gas in in every pipe and gas-tank in our city, and would tear up our streets and blow up our houses as suddenly and forcibly as if they had been mined with gunpowder. This is the chemic;al cause of gas and other explosions, —viz., the combustible materials being fully satlKated with oxygen and then ignited. The coals in our fires do not explode, because they are not saturated with oxygen, the supporter of combustion; the oxygen gradually com bines with the 'carbon in combustion, but if our coals were reduced to a state of gas, and the gas mixed with twice' its weight of oxy gen, the mixed gas would ignite instantaneous ly when a match was applied, and cause what is termed an explosion—which is but instan taneous combustion; a fire is slow combus tion, that is all the difference between the two. Those who keep volatile. hydro-car bons, such aS alcohol, turpentine, or miktures of these two fluids in stores, 'c., should be Very careful and not suffer them to be acted upon by heat so as to cause evaporation and saturation with the oxygen of the atmosphere, which is simply—to use a solecism—a gun powder gas.