Caloric, then, exists in all bodies, and has a constant tendency to equalize itself, as far at least as its outward manifestation, called temperature, is concerned; for if a _hot_ body be brought near colder ones, it will give up heat to them, until by its loss and their gain they all become of the same temperature; and this proceeds more or less rapidly, according as the original difference of temperature was greater or less. Some other circumstances also influence this equalization. The converse will take place on introducing a cold body among warmer ones, when heat will be abstracted from all the bodies within reach of its influence, until it has absorbed sufficient caloric to bring its own temperature to an equality with theirs. This is the true explanation of the apparent production of _cold_. When, for instance, an iceberg comes across a ship’s course, it appears to _give out_ cold, whereas it has abstracted the heat from the air and sea in its neighborhood, and they in turn act upon the ship and everything in it, until one common temperature is produced in all the neighboring bodies. It does not follow that the bodies thus equalized in temperature contain equal quantities of caloric; far from it. Each body requires a particular quantity of caloric to raise its temperature through a certain number of degrees; and such quantity is called its _specific_ caloric. A pound of water, for instance, will take just twice as much caloric as a pound of olive oil, to raise its temperature through the same number of degrees; the _specific_ caloric of water is therefore double that of oil. Mix any quantity of oil at 60 deg. of temperature with an equal weight of water at 90 deg., and you will find the temperature of the mixture to be nearly 80 deg., instead of only 74 deg. or 75 deg., showing that while the water has lost only 10 deg. of caloric, the mixture has risen 20 deg. If the oil be at 90 deg., and the water at 60 deg., the resulting temperature will be only 70 deg., or thereabouts, instead of 75 deg., the mean; thus, here the hot oil has lost 20 deg., while the mixture has risen only 10 deg.; the water, then, contains at the same temperature _twice_ as much caloric as the oil; its specific caloric is _double_ that of the oil. This mean temperature does result when equal weights of the same body at different temperatures are mixed together.