He could not watch the condition in which the gas was; but it was probably liquefied, for, when a valve was suddenly opened, it began to bubble furiously, and rushed out in the form of steam. Pictet thought he had also succeeded in liquefying hydrogen, the foggy vapor of the jet being of a steely grey color; for hydrogen has long been suspected to be a metal, of which water is an oxide, and hydrochloric acid a chloride. Nay, some solid fragments came out with the jet of vapor, and fell like small shot on the floor, and at first the sanguine experimenter thought he had actually solidified the lightest of all known substances. This, however, was a mistake; it was some portion of his apparatus which had got melted. Neither had the liquefaction of oxygen or nitrogen been actually witnessed, though the result had been seen in the jet of foggy vapor. Cailletet was on the point of trying his experiment over again in vacuo, so as to get a lower temperature, when the telegrams from Wroblewski showed that the Pole had got the start of him. Along with a colleague, Obszewski, Cailletet’s disloyal pupil set ethylene boiling in vacuo, and so brought the temperature down to two hundred and seventy degrees Fahrenheit below zero. This was the lowest point yet reached, and it was enough to turn oxygen into a liquid a little less dense than water, having its “critical point” at about one hundred and sixty-eight degrees Fahrenheit below zero. A few days after, nitrogen was liquefied by the same pair of experimenters, under greater atmospheric pressure at a somewhat higher temperature. The next thing is to naturally ask: What is the use of all this? That remains to be proved. The most unlikely chemical truths have often brought about immense practical results. All that we can as yet say is, that there is now no exception to the law that matter of all kinds is capable of taking the three forms, solid, aqueous, gaseous.