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EXOPHTHALMIC GOITER 76 EXPLOSIVES EXOPHTHALMIC GOITER, enlarge- ment with turgescence of the thyroid gland, accompanied by protrusion of the eyeballs, breathlessness, palpitation, and anaemia. Also called Basedow's or Graves' disease. EXPANSION, in physics, is the en- largement or increase in the bulk of bodies, in consequence of a change in their temperature. This is one of the most general effects of heat, being com- mon to all bodies whatever, whether solid or fluid. The expansion of fluids varies , considerably, but, in general, the denser the fluid, the less the expansion; and, commonly, the greater the heat, the greater the expansion; but this is not universal, for there are cases in which expansion is produced, not by an in- crease, but by a diminution of tempera- ture. Water, in cooling, ceases to con- tract at 42° F. ; and at about 39", just before it reaches the freezing point (32°), it begins to expand again, and more and more rapidly as the freezing point is reached. This expansion is about one-eleventh of its hulk, and ac- counts for the bursting of pipes, etc., when water is freezing in them. EXPATRIATION, the act or state of banishment from one's native country; also the voluntary renunciation of the rights and liabilities of citizenship in one country to become the citizen or subject of another. In the early part of the 19th century, the United States was almost the only nation that claimed for indi- viduals the right of expatriation with- out the consent of the government of which they were citizens or subjects. The European nations, as a rule, main- tained that the permission of the sover- eign was necessary; and the enforcement by England of this claim was one of the causes of the War of 1812. It must be said, however, that notwithstanding the position of the United States in regard to citizens or subjects of foreign powers, the right of voluntary renunciation of allegiance to the United States by one of our citizens was unsettled, so far as legislation was concerned, till the act of Congress of July 27, 1868, asserted that expatriation "is a natural and in- herent right of all people," but the ac- tion of the Department of State had previously seemed practically to admit the right. As far as foreign States are concerned, however, the United States has steadily maintained its original posi- tion. The first formal recognition of its claims was secured in an expatriation treaty with the North German Confed- eration, signed Feb. 22, 1868. England first recognized the right of voluntary expatriation by act of Parliament in 1870, and immediately concluded an ex- patriation treaty with the United States. All the leading nations of Europe now recognize the right, including besides those just mentioned, France, Austria, Russia, Italy, and Spain. EXPECTORANTS, in pharmacy, med- icines which favor the discharge of mu- cus from the windpipe and air-passage3 of the lungs, EXPLOSIVES are substances which, by sudden decomposition or chemical ac- tion, produce large volumes of heated gas. The decomposition can be brought about by heat, by a blow or by other means. All explosives in actual use are those in which the chemical action is one of oxidation, the oxygen being supplied either by a nitrate or chlorate, nitric acid or an NO2 group. The ease with which an explosion can be brought about depends very largely on the physical condition of the explosive. For instance, gunpowder varies widely in its effects, according to the size of the particles composing the mixture. While the force of all explosives is increased by inclos- ing them in a small space, confinement is not necessary in the ease qf_ those compounds in which decomposition is very rapid, as, for instance, mercury fulminate. JDftMPIN (CA(?-n?!P6e I M///}//>//A EXPLOSIVES A. Blasting charge B. Cross section of primer In an article of this length it wouW be impossible to deal, even briefly, with all substances of an explosive nature, but as far as possible, representative types of all the well-known groups will be described. 1. Explosive mixtures, as distinct from explosive compounds, consist of two or more substances, at least one of which is a combustible, and at least one