Probably the most remarkable property of water is its power of solution. No other liquid surpasses water as a solvent. This power, as has been pointed out, is supposed to be due to, or in some way correlated with, the extra valences of the oxygen atoms, which may perhaps unite with similar extra valences of other substances with which the water is brought into contact, and so cause the latter to enter into solution. All kinds of substances dissolve in water, and when in solution, or even when only moistened, are much more active chemically than when dry. This property of water contributes greatly to the possibilities of the chemical reactions which constitute life processes. Water, likewise, has a higher dielectric constant than any other common liquid. This means that it does not readily conduct electricity, or readily permit electric equilibrium to be established in it; or, in other words, that it is a good insulator. This property permits the existence in it simultaneously of materials having opposite electric charges, or the so-called ionization phenomena; hence, water is the best-known ionizing medium, and ionization favors chemical reactivity. Again, water has a very high specific heat, a fact which is of the utmost biological importance. It takes more heat to raise the temperature of one gram of water through one degree than is required to produce the same result in any other known substance; or, stated the other way around, a given amount of heat will cause less change in temperature of water than of any other known substance. Further, the latent heat of liquefaction and of vaporization (i.e., the amount of heat required to change the substance from solid to liquid and from liquid to gaseous state, respectively) is greater for water than for any other common substance. These facts are of very great importance in cell-protoplasm. The high specific heat of water provides that the heat liberated by the chemical reactions which take place in the protoplasm can be absorbed by the water of the cell contents, and given off again to other reactions, with very slight effect upon the temperature of the protoplasm itself. Hence, violent changes in temperature, which might be disastrous to the life of the cell, are prevented by the high specific heat of the water which it contains. Similarly, the high latent heat of liquefaction of water, resulting in the giving up of large quantities of heat before it can become solid, or "freeze," tends to prevent freezing and thawing of the cell contents with sudden changes of external temperatures at or near the freezing temperature of water.