An ester is decomposed also ‹under the influence of acids›, in aqueous solution, into an organic acid and an alcohol, and cane sugar is similarly decomposed into glucose and fructose (grape sugar and fruit sugar): C_{12}H_{22}O_{11} + H_{2}O → C_{6}H_{12}O_{6} + C_{6}H_{12}O_{6}. Both actions are found to be caused by the influence of the ‹hydrogen ions› of the acids used and to proceed, at a given temperature, ‹with a velocity proportional to the concentration of the hydrogen ions›. Now, in 0.1 molar solution, acetic acid is very little ionized (1.3%), as compared with hydrochloric acid (91%), the degrees of ionization being determined by conductivity measurements (p. 50); the relation may easily be demonstrated with the aid of the conductivity apparatus used to show the difference in ionization between potassium hydroxide and ammonium hydroxide. In the presence of 0.1 molar hydrochloric acid, the decomposition of cane sugar actually proceeds at 79 times the rate that it does in the presence of 0.1 molar acetic acid. The ratio of the concentrations of the hydrogen-ion in the two [p082] solutions is, in fact, 70 : 1. There is, therefore, close agreement[142] between the ‹relative chemical activity› of the two acids and the relation demanded, if we assume, on the basis of the theory of ionization (p. 77), ‹that the chemically active components of the acids are their ions and particularly their hydrogen ions›. In the following table, the relative activities of acids, in accelerating the decomposition of methyl acetate by water, are contrasted, in a similar fashion, with their relative conductivities. The conductivities of acids depend to such an extent on the concentration of hydrogen-ion, which moves five times, or more, faster than the anions and carries therefore the greater part of the current, that the conductivities of acids, in equivalent concentrations, may be considered an approximate measure of their relative degrees of ionization and ‹of the concentrations of hydrogen-ion›. For the purpose of comparison the activity and the conductivity of molar hydrochloric acid are both represented by 100. All the acids were used in normal solutions. CHEMICAL ACTIVITY OF ACIDS AND THEIR IONIZATION.[A] Acid. Activity. Conductivity. Hydrochloric acid 100 100 Nitric acid 92 100 Sulphuric acid 74 65 Acetic acid 0.3 0.4 Formic acid 1.3 1.7 Chloracetic acid 4.3 4.9 Tartaric acid 2.3 2.3 TABLE NOTE: A. Whetham, ‹Theory of Solutions›, p. 338.