62 ACETIC ACID ACHAEAN LEAGUE GAB.) The acetic acid employed in commerce is chiefly derived from the dry distillation of wood. The process, as described by the late William Allen Miller, is substantially as fol- lows : Harder kinds of wood, particularly the oak, beech, birch, and ash, are subjected to destructive distillation in iron retorts by means of a heat gradually raised to low redness. The wood is usually placed in these retorts in loose iron cases, by which means the charge can be rapidly introduced without loss while the re- tort is still hot, and the charcoal can be with- drawn when the distillation is complete. The quantity of acid obtained varies from H to 3 per cent., and in the crude state is called pyro- ligneous acid, in allusion to the mode of its formation (Gr. nvp, fire, and Lat. lignum, wood). During the operation a large quan- tity of tarry matter comes over, accompanied also by volatile arid inflammable bodies, among which wood spirit, methyl acetate, and acetone predominate. These bodies are condensed in suitable receivers, while, in addition to car- bonic anhydride, a considerable quantity of combustible gases, composed chiefly of hydro- gen and carbonic oxide, is directed into the furnace, where they serve as fuel, and aid in heating the retorts. In about 24 hours, or as soon as the gases cease to escape, the loose iron cylinders containing the wood are with- drawn, and immediately closed with an air- tight cover, so as to allow the charcoal to cool excluded from the atmosphere. The crude acid liquid which has been collected in the condenser is decanted from the tar, and, when submitted to distillation, furnishes wood naph- tha, which constitutes the more volatile por- tions; afterward the acetic acid is collected. The latter, however, is always accompanied by tarry matters. In order to get rid of these, the liquid is neutralized by^ the addition of the milk of lime or of sodic carbonate ; a quantity of tar rises to the surface of the liquid on standing ; this is skimmed off, and the solution of crude acid thus obtained is evaporated, and the dry residue, if the sodium salt be used, cautiously roasted at a temperature of about 500 F. (260 C.) to expel the tarry matters. It is afterward redissolved in water, decanted from the carbonaceous particles, which are allowed to subside, then recrystallized, and submitted to distillation with sulphuric or with hydrochloric acid, the sulphuric being prefer- able when sodic acetate is employed, while hy- drochloric acid answers best when calcic ace- tate is used. Properties of Acetic Acid. Nor- mal acetic acid, C H4 O, is liquid at temper- atures above 62-6 F. (17 C.) ; below this point it crystallizes in radiating tufts of plates, and is called glacial acetic acid. The concentrated acid has a sharp aromatic taste and a peculiar pungent odor ; it blisters the skin if applied to it for a sufficient length of time. It boils at 242 F. (117 C.), and may be distilled un- changed. Its maximum density is 1-073, cor- responding to a mixture of 77 -2 per cent, acid and 22-8 per cent, water. The vapor of acetic acid is inflammable, burning with a blue flame and producing by its combustion water and carbonic acid. ACETYLENE, a transparent colorless gas, of a peculiar disagreeable odor, perceptible when coal gas is imperfectly burned in the air. It burns with a bright smoky flame. Berthelot formed it by transmitting olefiant gas or marsh gas through red-hot tubes. When copper ser- vice pipes are used for distributing coal gas, a dark-red copper compound is sometimes de- posited which detonates powerfully on the ap- plication of heat or on receiving a sudden blow. Some serious cases of explosions in New York, where the pipes were undergoing repairs, were traced by Dr. John Torrey to this cause. When mixed with chlorine, acetylene explodes spon- taneously ; it has not yet been liquefied by cold or pressure. V < 1 1 K I > LEAGUE. The inhabitants of Achaia were a very inconsiderable member of the Hellenic family until about 251 B. C. They formed 12 separate self-governing communi- ties, united together only by the religious bond of a common temple, common festivals, and common ancestry. In the repulse of the Persian invaders, in the Peloponnesian war, and in the resistance to Macedonian conquest, they took little part ; and it was not until Athens, Thebes, and Lacedaemon had been subdued or humbled by Macedonian suprem- acy, that the insignificant Achaeans became illustrious. When the Macedonian monarchy was reeling beneath the invasion of the Gauls, four Achaean towns formed a league for mutual protection in 281. Soon afterward ^Egium ejected its garrison, and some others forced their tyrants, who governed in the Macedonian interest, to lay down their authority. In 251 Aratus, the Sicyonian, brought round his native town to the Achaean league, and got himself elected head of the confederacy. Corinth was freed from its garrison in 243 by the aid of the league, and was admitted a member. Megara, Epidaurus, Troezen, and the Arcadian cities joined soon after. In 208 Philipoamen, of Megalopolis, succeeded Aratus as general of the league. At this time, and especially after the total defeat of the Macedonian monarch at Cynoscephalee, it was the only powerful state left in Greece, and the only possible bulwark against Roman power. When Sparta joined the league in 191 it included almost all the cities of the Peloponnesus, together with Athens, and several cities of northern Greece. For 50 years the Achaean confederation main- tained the cause of Hellenic independence, and delayed the day of submission to Rome. (See GKKKCK.) At last the Roman senate succeeded in getting grounds of quarrel with the league, and sent Mummius over .to complete the sub- jugation of Hellas. This was done in 146 by the defeat of Diseus, the general of the con- federates, before the walls of Corinth. All Greece was then made into a Roman province,
