There must be an immense number of compound salts, since there is so great a variety of salifiable radicals, as well as of salifying principles.
MRS. B.
Their real number cannot be ascertained, since it increases every day. But we must not proceed further in the investigation of the compound salts, until we have completed the examination of the nature of the ingredients of which they are composed.
The 4th law of chemical attraction is, that a change of temperature always takes place at the moment of combination. This arises from the extrication of the two electricities in the form of caloric, which takes place when bodies unite; and also sometimes in part from a change of capacity of the bodies for heat, which always takes place when the combination is attended with an increase of density, but more especially when the compound passes from the liquid to the solid form. I shall now show you a striking instance of a change of temperature from chemical union, merely by pouring some nitrous acid on this small quantity of oil of turpentine—the oil will instantly combine with the oxygen of the acid, and produce a considerable change of temperature.
CAROLINE.
What a blaze! The temperature of the oil and the acid must be greatly raised, indeed, to produce such a violent combustion.
MRS. B.
There is, however, a peculiarity in this combustion, which is, that the oxygen, instead of being derived from the atmosphere alone, is principally supplied by the acid itself.
EMILY.
And are not all combustions instances of the change of temperature produced by the chemical combination of two bodies?