Dualism

Dualism. 1. In Philosophy, the recognition of two distinct conflicting principles or deities in the world. [Manich.eans.] Christianity is not properly dualistic, as it regards the powers of evil as created and temporary. 2. In Chemistry, dualistic doctrines regarding the constitution of bodies largely prevailed during the early portion of the present century, chiefly through the influence of the Swedish chemist, Berzelius. He regarded all elements as either electro-positive or electro-negative, and thought that compounds were always formed by the union of oppositely electrified atoms, such compounds being themselves positive or negative according to whichever kind of electrification was in excess. Two compounds could then unite with one another, but it was essential that one should be positive and the other negative. He supposed all salts to be formed by the union of two oxides - one an acid electronegative oxide, the other a basic electro-positive oxide, and extended his dualistic ideas to substances other than salts or organic compounds. Acids were regarded as compounds of acid oxides with water, and hence all acids should necessarily contain oxygen. The proof of the existence of acids in which this element was not present, e.g. hydrochloric acid, HCE, prussic acid, HCN, was one of the first blows to these ideas. Another tenet of the theory was that no atom could take the place of an oppositely electrified atom in a compound. The discovery of compounds in which elements such as chlorine may replace hydrogen with but little alteration in the general properties of the compound, e.g. in chloracetic acid, was in direct contradiction to the dualistic views and finally led to their overthrow and the formation of a type theory, which might be regarded as the foundation of the present system of chemical classification.