ATOCIUM

(Lat.), n, n. 'si2(ki2)-utm(utm). 1. The Lychnis silvestris. {Pliny (B, 184).] 2. See AToctoy. ATOCIUS (Lat.), adj. 'si2(ki2)-u%s(uts). See AToios. ATOCIVE (Fr.),n. AS-to-sev. The Anona squamosa. [L, 49.] ATOCOS, ATOCUS (Lat.), adj’s. A*t(a*t)’o(0?)-ko%s, -ku2s- (kus). Gr., droxos. 1. Nulliparous. 2. Barren. [A, 811, 322.] ATOLE, n. The Bixa orellana or the dye (an not to) obtained from it. [B, 173, 180.] ATOLLIDÆ (Lat.), n. f. pl.. A family of Hydrozoa belonging to the order Disco med usæ, suborder Cubostomæ. [E. R. Lankester (B, 77).] ATOM, n. A?t/o%m. Gr., éropos (from a priv., and répvew, to cut). Lat., atom us. Fr., atome, Ger, Atom, Urstofftheilchen. It., atomo. Sp.,dtomo. 1. In Tienes and physics, a supposititious, exce ively small, indivisible, and unalterable particle of matter. By the aggregation of a’s all substances were supposed to be formed, differences in their physical properties being attributed to differences in the a’s themselves or in the arrangement and location of the component a’s. This conception of an a. dates back to the time of Anaxagoras, Demo crit us, and Lucretius, and still exists in a somewhat modified form. [B.] See MoLECULE and Atomic THEory, 2. In Che ttp a name given by Dalton to the smallest jetta of a body, whether elementary or compound, which could » imagined to exist by itself or in combination. His definition thus includes both the a. and the molecule of recent chemistry. {8 3. In recent chemistry, the smallest conceivable portion of an elementary body which can preserve the chemical Ree of the body, and go into and out of combination. [B.], MoLECULE.—A‘äihnlich (Ger.)._ Atom-like. [L, 46.]—A’gewieht (Ger.). i weight. [B.]-A’refraction (Ger.). See Atomic REFRACTION.— (Ger.). Atomic heat. [B.]—Chemical a. See A. (2d and 3d def's)—Compound a. A molecule. [B, 140.|—Elementary a. The a. of an elementary body; ana. in the chemical sense. [B; 140.]—Organic a. A molecule forming part of an organic compound. [B, 140.]—Physical a. See A. (Ist def.) and MOLECULE.— Simple a. See Elementary a.—Vortex-a. Fr.,atome-tourbitlon. The elementary constituent of a substance according to the so-called vortex theory of matter; a whirling ring (like the ring of smoke), being a portion of the infinitely attenuated, perfectly fluid ether sunnosed to permeate all space, to which portion a vortex motion has been communicated. Such a vortex-ring, pecanced ina perfect fluid (i. e., one in which no friction exists), has been shown by Helmholtz to be indestructible and indivisible. [Tait (B, 164).]