In a northern winter we may observe in air almost still, the wasting away of a large block of ice, so that during a week it loses a considerable part of its bulk. The giving forth of vapor is evidently not restricted to high or to ordinary temperatures, but may occur below the freezing point of water. In 1863, Thomas Graham, the eminent Scottish physicist, from many experiments with metals expressed the opinion that what seems to be a solid may be also in a minute degree both liquid and gaseous as well. Confirmation of this view was afforded in 1886 by Professor W. Spring, of Liege, who formed alloys by strongly compressing their constituents as powders at ordinary temperatures. It is probable that a slight pervasive liquidity gave success to the experiment. Professor Roberts-Austen once observed that an electric-deposit of iron on a clean copper plate adhered so firmly that when they were severed by force, a film was stripped from the copper plate and remained on the iron, signifying that the two metals had penetrated each other at an ordinary temperature. This interpenetration he found to take place through films of electro-deposited nickel. In a remarkable round of experiments he also found that at 100° C., a temperature much below the fusing point of lead, gold as leaf is slightly diffused through a mass of lead; when the lead is fluid at 550° C., the proportion of diffused gold is increased 160,000 times. This volatility of the particles of a heavy metal shows us plainly that virtual evaporation may be always taking place from metallic surfaces at ordinary temperatures,--a phenomenon which may be the same in kind as the pouring out of a perceptible stream of corpuscles under strong electrical excitation. The analogy goes further, at least in the case of liquids, which exhale a vapor usually different in composition from the parent body; take, for example, a solution of sugar in water which sends forth watery vapor only, or observe a mixture of much water and a little alcohol as it emits a vapor largely alcoholic and but slightly aqueous. Every Property May be Universal.