ZIZ 



zoo 



ZERO. Nothing; it is used to 

 designate the 0° point of graduated 

 scales, as the tiiermometer, areome- 

 ter, and usually means a degree equal 

 to a given test ; thus, the zero of tlie 

 areometer is the specific gravity of 

 pjre water at 59=' Fahr. ; the zero 

 of Fahrenheit's thermometer is tiic 

 temperature of snow mixed with 

 salt. The zero of the Centigrade 

 and Reaumer scales is the freezing 

 point. Degrees above zero are plus 

 (-[-), below it minus ( — ). 



ZERUMBET. An East Indian 

 rhizome, similar to ginger. 



ZIMOME. That part of the glu- 

 ten of wheat which is insoluble in al- 

 cohol. 



ZINC. Spelter. A valuable met- 

 al for rooting and the construction 

 of vessels, such as are made of tm 

 plate, than which it is more durable 

 and stronger. In chemistry, it is of 

 great use for the construction of gal- 

 vanic circles and batteries, forming 

 the positive surface or pole of single 

 circles. It is rapidly acted on by the 

 strong acids, and forms an oxide 

 which combines with most acids. Of 

 its salts, the sulphate, or white vit- 

 riol, is most employed ; it is emetic 

 and irritant, and used chiefly in lo- 

 tions. See Pharmacopeia. Calamine 

 is an impure native carbonate of zinc. 

 Tuitv is an impure artiticial oxide. 



ZINCOUS, ZINCOID, ZLNCODE. 

 Resembling zinc. This term is used 

 to designate any metal or other body 

 which, in a galvanic circle, occupies 

 the place of the zinc. It is the same 

 as positive metal or pole, positive 

 electrode, anode, and the derivatives. 

 Zincidysis means the same as elec- 

 trolysis ; zincolyte, as electrolyte. 

 These terms are indeed to be prefer- 

 red over those previously in exist- 

 ence, because they refer to the zinc 

 element, or its substitute, as the ori- 

 gin of the galvanic action. 



ZINGIBER. The generic name 

 of the ginger plant (Z. officinalis). 



ZIRCONIUM. A rare metal, the 

 base of zirconium. 



ZIZANTA. Wild rice. See Rice, 

 Wild. 



ZIZIPHUS. The generic name of 



the shrubs yielding the jujube {Z.jv, 

 juha). 



ZONE (from fwvj?, a belt). A word 

 nmch used by naturalists to denote a 

 band or stripe running around any 

 object. In geography, a division of 

 the earth's surface. There are five 

 great zones. The tropic or torrid 

 cone, occupying the central or equa- 

 torial regions of the earth to a dis- 

 tance of 23^ degrees north and south, 

 and therefore having a width of 47 

 degrees. The north temperate zone 

 lies between 23^ N. lat and 66^ N. 

 lat., and occupies 43^ of latitude. The 

 south temperate zone lies in the same 

 space on the south side of the globe. 

 The north and south frigid zones oc- 

 cupy the space beyond 66t degrees 

 to the poles : they are also called the 

 arctic and antarctic regions. 



ZOOLOGY (from fwoi', an animal, 

 and ?.oyoc. a discourse). The history 

 and classification of animals. The 

 objects of the animal kingdom are so 

 extremely various that a classifica- 

 tion of them is one of the severest 

 labours. Numerous suggestions have 

 been made as a basis for classifica- 

 tion, but the advance of knowledge 

 has shown them all to be wanting in 

 comprehensiveness. When it is re- 

 membered that under the term ani- 

 mal is grouped thousands of species 

 differing from the scarcely organized 

 and imperceptible dots of jelly called 

 monads, to the most complicated quad- 

 rupeds, the difficulties of classifica- 

 tion will be apparent. The following 

 view by Professor Owen is the most 

 complete we have seen. 



In this there are four primary di- 

 visions, or sub-kingdoms : 1. Verte- 

 brata, or animals furnished with a 

 regular back bone ; 2d. Artieulata, 

 animals which contain no internal 

 skeleton, but are covered with a crust 

 or shell made of distinct parts or ar- 

 ticulations, as the lobster; 3d. Mol- 

 lusca, animals destitute of skeleton or 

 articulations, hut usually inhabiting 

 shells ; and, 4th. Kadiata, animals of 

 the lowest organization, destitute of 

 an internal respiratory organ, and 

 having a nervous system composed 

 of mere Lines, which are often radia- 



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