SOCRATES SODA 149 He commented upon all the imputations, and denied some. He mentioned his blameless life, his divine commission, and the consequent antipathies which he aroused, refuted the charge of irreligion, maintained a calm, brave, and almost haughty bearing, and declared his solicitude rather for the good repute of the Athenians than for himself. He heard with- out surprise the sentence of condemnation, which was passed by a majority of only five or six in the Athenian dicastery of 567 members. It is probable that the prosecution was de- signed rather to humble than to destroy him. Xenophon affirms that the defiant and fearless tone of his defence was the direct cause of his condemnation ; and it is certain that the capi- tal sentence which followed it was the conse- quence of his libera contumacia, as Cicero ex- presses it. The penalty of death having been pronounced, he declared himself satisfied both with his own conduct and with the result, cal- culated that his bearing on the trial would be the most emphatic lesson which he could read to the youth of Athens, and predicted that his removal would be the signal for numerous suc- cessors in so worthy a work. An interval of 30 days was allowed for the annual Theoric mission of the sacred ship to Delos, which he passed in prison, with chains on his legs, in conversation with his friends. The Platonic dialogues of "Crito" and "Phsedo," in addi- tion to their historic value, may be regarded as imitations or developments of his last argu- ments on the duty of obedience to the laws and on the evidences of immortality. There is no authority but that of late and untrust- worthy writers for the statement that the Athenians lamented his fate and punished his accusers. The Memorabilia of Xenophon and the dialogues of Plato have been supposed to represent an exoteric and an esoteric Socra- tes, and there has been a long controversy as to which contains the most complete and true history. The former professes to record ac- tual conversations held by him, and was de- signed as an apology ; while the Socrates of the latter is the spokesman of theories which may or may not have been the opinions of the master as well as the disciple. But the two pictures thus presented are in the main accor- dant. Socrates marks the epoch in Greek phi- losophy when speculation turned from physics to ethics. He directed his attention to hu- man relations and duties. Astronomy he pro- nounced a divine mystery ; geometry he val- ued only for land-measuring ; general physics he discarded altogether as having furnished and promising nothing but hypothetical, con- trary, and useless results ; human practice alone, with the knowledge pertaining to it, was es- teemed the proper subject of human investiga- tion. According to Cicero, "Socrates called philosophy down from the heavens to earth, and introduced it into the cities and houses of men, compelling men to inquire concerning life and morals and things good and evil." The most complete discussions concerning Socrates are in general histories of Greece and of phi- losophy. See also Moses Mendelssohn's life of Socrates, prefixed to his own Phcedon ; Nares, " An Essay on the Demon or Divination of So- crates" (1782) ; Wiggers, Sokrates als Hensch, Burger und Philosoph (1811); Schleiermacher, Ueber den Werth des Sokrates als PhilosopJien (1815-'18) ; Lelut, Du demon de Socrate (1 836) ; K. F. Hermann, De Socratis Accusatoribus (1854); and Zeller, "Socrates and Socratic Schools " (1868). Ueberweg's " History of Phi- losophy" (1872), vol. i., pp. 80-88, contains a full list of works. SODA, a name given to sodic monoxide, or common oxide of sodium, NasO, the base of the important series of sodium salts ; also to the hydrated oxide, or caustic soda, NaHO, and in commerce to the normal carbonate, Na 2 C0 3 + 10H 2 0. Anhydrous sodic monoxide, or the soda of the chemist, KaaO, is formed when the metal is burned in dry air or oxygen gas, by exposing the dioxide to a high heat, or by heating sodic hydrate with an equivalent quan- tity of metallic sodium, whereby NaHO-fNa is converted into ]STa 2 O + H. When sodium is burned in oxygen gas till its weight is constant a dioxide, Ka 2 3 , is formed. When exposed to the air it deliquesces, and, uniting with car- bon dioxide, resolidifies as carbonate. When a heap of it is moistened it becomes heated and evolves oxygen gas. The monoxide attracts moisture as powerfully as the corresponding potassic oxide, forming sodic hydrate or caustic soda, from which the water cannot be expelled by heat alone. The properties of caustic soda resemble those of caustic potash, and it may be prepared from the carbonate by a similar method (see POTASH, vol. xiii., p. 756) ; but its action upon acids is rather less energetic. Its specific gravity is 2'13. It is manufactured on a large scale in the alkali works accord- ing to a process proposed by Mr. Gossage, by which advantage is taken of the presence of caustic soda in the black ash solution. The crude solution of black ash vats is evapora- ted to a specific gravity of 1'5 or 1'6, during whieh operation most of the carbonate, sul- phate, and chloride crystallize out. The " red liquor," as it is technically called, which owes its color to a compound of sulphide of sodium and sulphide of iron, and which is also con- taminated with ferrocyanide and sometimes with sulphocyanide of potassium, has air forced through it while hot, which causes the precipi- tation of the iron as sesquioxide and the con- version of the sulphur compounds into sul- phates. The addition of sodic nitrate com- pletes the oxidation, and this salt may be used for the whole process. After its addition the evaporation is carried further until the whole mass is heated nearly to redness. When the temperature rises to 311 large quantities of ammonia are evolved, and as it increases ni- trogen escapes abundantly. The fused soda is poured into sheet-iron vessels, in which it so-
