A Z O 



globofe, of one cell and one valve, in an ovate, clofe invo- 

 lucrum. Seeds feveral, angular. 



1. K. Jllktiloides. South-American Azolla. Lamarck 

 II. 1. t. 863. (A. magellanica ; Willd. n. i. Mufcus fqua- 

 mofus aquaticus elegaiitiffimus ; I'euiU. Voy. v. 3. 43. t. 35. 

 Dill. Mufc. 335. t. 43. f. 72.) — Frond pinnate. Leaflets 

 all papillary. Roots fmooth. — Found by Feuillee in Peru ; 

 by Mr. Menzies in Chili ; in watery places ; and at the 

 ftraits of Magellan by Commerfon. This is a little floating 

 iTiofTy plant, refembling a Jungermannia, an inch or two 

 long, alternately pinnate, with fmal!, imbricated, ovate, 

 flefliy leaves, clothed externally v/ith papillary hairs, and 

 membranous at the edges. The roots are long, flender, 

 fmooth and naked, dark brown. No frutlification has been 

 difcovered in this fpecies. 



2. A-. pinnata. Triangular Pinnate Azolla. Br. n. i. 

 Bot. of Terra Auftr. 79. t. 10. — Frond pinnate, triangu- 

 lar. Upper leaflets papillary. Roots longitudinally fea- 

 thery. — Gathered by Mr. Brown, in lakes and ponds, at 

 Port Jackfon, New South Wales. A little floating plant 

 like the foregoing. Roots axillary, folitary, perpendicular, 

 unbranched, pellucid, hooded at the point when young, 

 at firft fight quite fimple, but under a magnifier they 

 appear feathery about the middle part. Frond half an mch 

 long. Branches two-ranked, alternate, crowded. Leaves 

 alternate, imbricated every way ; thofe on the upper fide of 

 each branch ovate, fomewhat angular, cellular, thick, often 

 reddilh, rough on the upper furface with papillary tubercles ; 

 thofe on the under fide thinner, fmooth, and lefs angular. 

 Flo'uiers on the under fide of the frond, feffile, folitary at 

 the bafe of each branch. 



Mr. Brown feems to think the true pollen of this curious 

 genus originates in the watery or turbid fluid, which he 

 once found changed to powder, and which may be difcharged 

 through the tube above, whofe angular appendages, once 

 fufpefted to be anthers, (fee bis Prodr.) may by preflure 

 facihtate its ejeftion, whether in a watery or powdery 

 ftate. 



7,. A. rubra. Red Orbicular Azolla. Br. n. 2 — Frond 

 orbicular ; lobes palmate ; their fubdivifions undivided or 

 cloven. Upper leaves fmooth. Roots feathery beyond the 

 middle. — Gathered by Mr. Brown, at Port Jackfon, as well 

 as in Van Diemen's illand. The fruftification has eflbntially 

 the fame ilruiture of that of Jl. pinnata, except the an- 

 gular bodies of the upper cell being only fix, not nine. 

 Broiun. 



4. A. carolhnana. Carolina Azolla. Willd. n. 2. 



Purfh n. I " Leaves imbricated, ovate-oblong, obtufe, 



fpreading ; red underneath." — Found by Richard, in Caro- 

 lina ; by Purfh floating on the waters of lake Ontario. We 

 know nothing more of this fpecies ; and as thofe who have 

 defcribed it were unacquainted with the fruftification, as well 

 as with Mr. Brown's fpecific definitions, the above charafter 

 requires revifion. 



AZORELLA, Lamarck Dift. v. i. 344. lUuftr. 

 t. 189. JuiT. 226. 453. See Chamitis, as well as BoLA.x 

 hereafter. 



AZOTE, in Chemijlry. The fpecific gravity of azote, 

 according to the moft recent deternninations, is .9722, and 

 1 00 cubic inches of it will weigh, at a mean temperature 

 and prefTure, 29.652 grains. Biot and Arrago make its 



A Z U 



ipecific gravity .9691, and Lavoifier .978. See Atomic 

 lieory. 



A new compound of. chlorine and azote was difcovered 

 a few years ago, which, from its remarkable properties, 

 deferves to be defcribed here. 



This compound feems to have been firfl: noticed by 

 M. Dulong in 181 2 ; but this chemift;, on account of two 

 fevere accidents which happened to him in the courfe of his 

 experiments, did not complete the inveftigation of its pro- 

 perties, nor publiih any thing on the fubjeft. Sir H. Davy 

 was informed of the difcovery of the fubfl;ance foon after, 

 but not of the method of preparing it. Chancing, however, 

 to hear from Mr. Children, that Mr. Burton 'of Cambridge 

 had procured an oily fubft^ance by palling a current of chlo- 

 rine through a folution of nitrate of ammonia, he was enabled 

 to prepare the compound in queftion, and inveftigate its pro- 

 perties. 



Chloride of azote may be prepared by placing a jar of 

 chlorine gas over a folution of nitrate or muriate of ammo- 

 nia, heated to about 110°. The gas is flowly abforbed, and 

 an oily-like matter collefts at the bottom of the velTel, which 

 is the fubilance in queftion. Care muft be taken not to 

 colleft at one time more than a" globule or two, as it ex- 

 plodes with prodigious violence from the flighteft caufe. 

 Its colour clofely refembles that of olive-oil. It is tranf- 

 parent : its fmell is ftrong and peculiar, though it is not fo 

 difagreeable nor injurious to the lungs as chlorine. It is 

 very volatile, and foon difappears when left in the open air. 

 At 160° it may be diflilled over without danger, but is par- 

 tially decompofed. The temperature of 2CX)° only occafions 

 it to evaporate fafter, but when heated to 212° it explodes 

 with amazing force. In a vacuum it is converted into 

 vapour, but again aflumes the liquid form when the preflure 

 of the air is reftored. This vapour, if heated fufBciently, 

 explcdes with as much violence as the liquid itfelf. The 

 fp. gr. of the chloride of azote is 1.653. ^' ^^'^^ "^t 

 become folid on expofure to cold. When left in water it 

 fpeedily difappears, and azotic gas efcapes. In ftrong 

 muriatic acid, chlorine efcapes, and muriate of ammonia 

 remains in folution. When brought in contaft with phof- 

 phorus, oils, and many other fubftances, it explodes with 

 very great violence. Metals, refins, fugar, and moft of the 

 gafes, do not caufe it to explode. The experiments of fir 

 H. Davy on the compofition of this curious fubftance 

 render it probable, in Dr. Thomfon's opinion, that it is 

 compofed of one volume or atom of azote, and four volumes 

 or atoms of chlorine. 



Azote has likevvife the property of forming an analogous 

 compound with iodine. (See Iodine, and Simple Bodies.) 

 The celebrated chemift Berzelius itill, we believe, main- 

 tains the opinion, that azote is a compound of oxygen 

 and an unknown fubftance, which he denominates r.itricum ; 

 and a laborious fct of experiments was fome time ago pub- 

 lifhed by Mr. Miers, to fhew that this unknown fubftance is 

 nothing but hydrogen. Chemifts in general, however, do not 

 at prefent acquiefce in either of thefe opinions, but confider 

 azote as an elementary fubftance. 



For the combinations of azote with oxygen, fee Atomic 

 Theory, Nitric Acid, (ffc. and Proportions, Dejlmte. 



AZUMBRE, a liquid meafure in Spain. See Arroba, 

 Addenda. 



