ZO A 



ZOO 



electrode, the anode, and the zincode. 

 See Polarity^ Chemical. 



ZINCO'LYSIS. A term equivalent to 

 electrolysis, denoting a mode of decom- 

 position occasioned by the inductive ac- 

 tion of the afTinities of zinc or the positive 

 metal. 



ZI'NCOLYTE. A term equivalent to 

 electrolyte, denoting a body decomposihle 

 by electricity, the decomposition being 

 referred to the action of zinc or the posi- 

 tive metal. 



ZINCOUS ELEMENT. The basic or 

 positive element of a binary compound. 

 The negative is termed the chlorous ele- 

 ment. 



ZINCOUS POLE. A term founded 

 on the theory that the particles of matter 

 are susceptible of polarity. Hence that 

 pole of a particle of zinc or of hydrochloric 

 acid which has the attraction, or affinity, 

 which is characteristic of zinc, or zincous 

 attraction, is called the zincous pole. See 

 Chlorous Pole. 



ZINGIBERA'CEiE. ScitaminecB. The 

 Ginger tribe of monocotyledonous plants. 

 Aromatic tropical herbaceous plants, with 

 a creeping rhizome, and stem formed of 

 the cohering bases of the leaves ; inflo- 

 rescence either a dense spike, or a ra- 

 ceme, or a sort of panicle, terminal or 

 radical. The family are monandrous, 

 with a whole anther, and are thus distin- 

 guished from the allied family maran- 

 tacecc, which are monandrous, with only 

 half an anther ; and from the musacece, 

 which have five or six anthers. 



ZI'NKENITE. A mineral containing 

 sulphur, lead, antimony, and copper. It 

 is nearly related to plumose antimony. 



ZIRCON. A heavy, hard, sparkling, 

 and transparent stone, having a strong 

 double refraction. It is usually divided 

 into the two varieties of hyacinth and 

 jargon, the former having a yellowish-red 

 colour, and the latter being most esteemed 

 when colourless. 



ZIRCO'NIA. The oxide of zirconium; 

 a peculiar earth, discovered in the zircon 

 of Ceylon, a silicate of zirconia, which 

 is also found in the syenitic mountains of 

 the south-east side of Norway. The 

 hyacinth is the same mineral of a red 

 colour. 



ZIRCO'NIUM. The metallic basis of 

 zirconia, obtained in the form of a black 

 powder, resembling that of charcoal. 



ZOANTHA'RIA (faiov, an animal, 

 avOoi, a flower). Animal-flowers ; the 

 third class of zoophytes, in the arrange- 

 ment of De Blainville, who gives the fol- 

 383 



lowing definition : — " Body regular, 

 flower-shaped, more or less elongated, 

 free or fixed, very contractile, furnished 

 with an intestinal canal (?), without dis- 

 tinct walls, having a single large terminal 

 opening surrounded by variously-shaped 

 tentacuia, which are always tubular and 

 in communication with the musculo- 

 cavernous parenchyma of the skin." 



ZOA'NTHIDvE. A family of the 

 zoantharia of De Blainville, comprising 

 animals coriaceous, simple, or compound, 

 fixed; tentacuia marginal, surrounding 

 the mouth. 



ZO'DIAC (twaiOK, a little animal). The 

 area within which the apparent motions 

 of the sun, moon, and all the greater 

 planets are confined. It consists of a zone, 

 or belt, extending nine degrees on either 

 side of the ecliptic, and named from its 

 containing the figures of all the animals, 

 &c., which formed the twelve signs. The 

 names of the signs are derived from com- 

 parisons made by the Egyptians between 

 celestial and terrestrial phenomena, for 

 the most part purely of a local nature, 

 and belonging exclusively to a part of 

 their country. See Signs of the Zodiac. 



ZODl'ACAL LIGHT. A term applied 

 by astronomers to a revolving ring of 

 finely-divided or nebulous matter, situ- 

 ated perhaps between the orbits of Venus 

 and Mars, but certainly extending beyond 

 that of the earth. This phenomenon 

 rising pyramidally illumines a portion of 

 the unvarying length of the tropical 

 nights. In the temperate zone, it is only 

 distinctly visible in the beginning of 

 spring, when it may be seen after even- 

 ing twilight above the "Western horizon, 

 and at the end of Autumn, before the 

 commencement of morning twilight above 

 the Eastern horizon. 



ZO'ISITE. A subspecies of prisma- 

 toidal augite, distinguished into the com- 

 mon and the friable. It was named after 

 its discoverer, the Baron Von Zois. 



ZONE {zona, a girdle). The geogra- 

 phical denomination of each of the five 

 parallel belts into which the earth is 

 imagined to be divided in respect to tem- 

 perature. The torrid zone includes all 

 the space which lies between the tropics, 

 being nearly 47 degrees, or 23^ degrees 

 on each side of the equinoctial line. Two 

 frigid zones occupy those parts which lie 

 between the poles and the polar circles ; 

 and two divisions which lie between those 

 circles and the torrid zone, are called the 

 temperate zones. 

 ZO'OCARPES (fwov, an animal, Kap- 



