FeO SO3 + 7 HO.
These atoms of water are driven off by the application of heat, leaving a white substance, which is the Anhydrous salt, and would be written simply as FeO SO3.
The plus sign however is often employed in token of simple addition, no combination of any kind being intended. Thus the decomposition which follows on mixing Chloride of Sodium with Nitrate of Silver may be written as follows:—
NaCl + AgO NO5 = AgCl + NaO NO5;
that is,—
| Chloride of Sodium added to Nitrate of Silver. | |
| = | Chloride of Silver and Nitrate of Soda. |
ON EQUIVALENT PROPORTIONS.
When elementary or compound bodies enter into chemical union with each other, they do not combine in indefinite proportions, as in the case of a mixture of two liquids, or the solution of a saline body in water. On the other hand, a certain definite weight of the one unites with an equally definite weight of the other; and if an excess of either be present, it remains free and uncombined.
Thus, if we take a single grain of the element Hydrogen—to convert that grain into Water there will be required exactly 8 grains of Oxygen; and if a larger quantity than this were added, as for instance ten grains, then two grains would be over and above. So, to form Hydrochloric Acid, 1 grain of Hydrogen takes 36 grains of Chlorine:—for the Hydriodic Acid, 1 grain of Hydrogen unites with 126 grains of Iodine.
Again, if separate portions of metallic Silver, of 108 grains each, are weighed out,—in order to convert them into Oxide, Chloride, and Iodide of Silver respectively, there would be required