Note 43 — Chapter X · SODIUM CHLORIDE—BERTHOLLET'S LAWS—HYDROCHLORIC ACID

When an unsaturated hydrocarbon, or, in general, an unsaturated compound, assimilates to itself the molecules Cl2, HCl, SO3, H2SO4, &c., the cause of the reaction is most simple. As nitrogen, besides the type NX3 to which NH3, belongs, gives compounds of the type NX5—for example, NO2(OH)—the formation of the salts of ammonium should be understood in this way. NH3 gives NH4Cl because NX3 is capable of giving NX5. But as saturated compounds—for instance, SO3,H2O, NaCl, &c.—are also capable of combination even between themselves, it is impossible to deny the capacity of HCl also for combination. SO3 combines with H2O, and also with HCl and the unsaturated hydrocarbons. It is impossible to recognise the distinction formerly sought to be established between atomic and molecular compounds, and regarding, for instance, PCl3 as an atomic compound and PCl5 as a molecular one, only because it easily splits up into molecules PCl3 and Cl2.