Devours Like Fire

The alchemists of the middle ages believed that somewhere in the universe ■was to be found a universal solvent ■wbioh would dissolve the most refraotory substances as readily as -water disolves sugar. They uamed their solvent liquor alkahest, and what time they could spare t'rom the search after the elixir of life and the philosopher's ■stone was spent in the endeavor to obtain it. Science has yet to prove, by the way, that there was not more method in the rnadness of the alohemists than is generally supposed, for in the remarkable substanoe fluorine chemists possess material that approximates very closely to a universal solvent. Itschemical energy is so fleroe that, except gold and platinum, nothing can resist it, and even gold and platinum succumb to fluorine in tiníe. The mere contact of most substances with fiuorine is sufficient to canse not mere solution, but ligbt, ñame and fieroe detonations. Dull, inert flint takes fire vehen exposed to fluorine vapor and becomes a brilliant incandescent mass. Lampblack bursts into fíame, while charcoal burns with bright scintillations. Only the diamond is able to resist this powerful solvent, to which it does not succumb even at high temperature. The similar lement silicon, which can be obtained in a crystalline forrn closely resembling the diamond, gives a magniflcent display in the preseuce of fluorine, the crystals becoming white hot and throwing showers of fiery spangles in all diïectious. The heat is so intense that the crystals nielt, showing that their temperature has rcached 1,200 degrees C. Phosphorus combines fiercely with fluoriue. Prussian blue, on account of the cyanogen it contains, burns with a beautif ui pink flame ; while from a crystal of iodine placed in fluorine vapor a heavy liquid distills witha pale flame. This liquid - an iodide of fluorine - etches glass, and if thrown into water hisses like hot iron. The last uamed metal becomes white hot when exposed to fluorine; even iron rust behavea in a similar manner. Nearly all metáis are raised to vivid incandescence in a current of the gas, many appearing very beautiful, especially aluminium and ainc. If the latter be slightly warmed, it bursts into a white flame too dazzling to gaze at or describe. Although it bas been known in varius states of combination for many years, having been flrst discovered by Schwankhardt of Nuremberg, in 1670, and rediscovered by Scheeie in 1771, fluorine was not obtained as fluorine in the free state until about six years ago, when the Frenen chemist Moissan succeeded in isolating it by employing a current of electricity from 26 or 28 Bunsen batteries. The current was passed through the compound of fluorine and hydrogen known as hydrofluorio acid, which is similar to hydrochloric acid. To improve the couduptivity of the hydrofluoric acid it was necessary to dissolve another fluorine compound in the liquid. As wili readily be irnagiced, it is not so difficulttfo obtain free fluorine as to keep it when obtained. JEvery part of the apparatus used by M. Moissau was made of platinum, with screw joints andwashers of lead, which swell on contact with fluoriue, all the stoppers being of fluorspar. Fluorine has a powerful affluity for silicon, one of the principal constitueuts of glass, so that it was impossible to use glass vessels or tubes to contain the gas. As regards the chemical nature of fluorine, it is a gas at ordinary temperature and is the liglatest member of the series of elements containiug chlorine, bromine and iodine. The attraction. of fluoriue for hydrogen exceeds that of chlorine and is so great that if a slow curreut of fluorine gas be passed into a tube of fluorspar coutaining a drop of water a dark fog is produped, which changes presently to a blue vapor con gisting of ozoue - the coudensed forra of oxygen. The last narued substance appears to be oue of the few materials which bas noaftinity for fluorine. Nothing is obsarved to take place betweeu them even when they are heated up to 1,000 degrees F. So far all experimeuts had been conducted with fluoriue gas, which, at the time it was isolated, resisted all attempt3 to reduce it to the liquid state. Six years ago, however, there was no laboratory - such as that at the Royal institution - having powerful machiuery for producing liquid air or liquid oxygen at the commaud of the investigator. In fact, liquid air itself was practically unkuown. By the aid of this weapon Professors Dewar and Moissan have succeeded in liquefying fluoriue. At the Oxtreruely low temperature of liquid oxygen it was found that fluorine did not attack glass, and it was possible to ■use glass vessels tohold thenewly