A R S 



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ART 



strong garlicky smell, and deposits a white 

 powder. This metal and all its com- 

 pounds are virulent poisons. Combined 

 with sulphur it forms orpiment or realgar, 

 or the yellow and red sulphurets of ar- 

 senic. The term apviviKov, from which 

 the word arsenic is derived, was an an- 

 cient epithet, applied to those natural 

 substances which possessed strong and 

 acrimonious qualities, and as the poison- 

 ous quality of arsenic was found to be re- 

 markably powerful, the term was espe- 

 cially applied to orpiment, the form in 

 which this metal more usually occurred. 

 Dr. Paris, from whose work the above is 

 quoted, states that in the celebrated plague 

 of London, amulets of arsenic were worn, 

 suspended over the region of the heart, as 

 a preservative against infection ; on the 

 principle, so prevalent at one period, that 

 all poisonous substances possess a pow- 

 erful and mutual elective attraction for 

 each other. 



ARSE'NICAL. Containing arsenic. 



A'RSENITE. A name given by Fourcroy to 

 the combinations formed between oxide 

 of arsenic, or arsenious acid, and the 

 earths and alkalies. Arsenite of potassa is 

 the active ingredient in Fowler's Ague 

 Drop, and in the Liquor Potassse Ar- 

 senitis of the Pharmacopoeia. 



ARTE'RIAL. (arterialis, Lat. arterial, Fr. 

 arteriale, It.) Pertaining to an artery; 

 that is contained in an artery. 



A'RTERY. (from arjp, and TTJ/OSW, Gr. 

 artere, Fr. arterio, It. Thus called be- 

 cause the ancients thought that only air 

 was contained in the arteries.) The ar- 

 teries are strong elastic canals, which 

 convey the blood from the heart to the 

 different parts of the body, and, during 

 life, are distinguished from the veins by 

 their pulsation. The original trunks of 

 the arteries are two in number, and from 

 these all the other arteries are derived. 



ARTE'SIAN WELLS. Springs of water, or 

 fountains, obtained by boring through 

 strata destitute of water into lower strata 

 loaded with this fluid, to sometimes great 

 depths ; thus named from its having been 

 first practised at Artois, the ancient Ar- 

 tesium, in France. In forming an Ar- 

 tesian well, if the boring penetrate a bed 

 containing impure water, it should be 

 continued deeper until it arrives at ano- 

 ther stratum containing pure water ; the 

 bottom of the pipe being plunged into 

 this pure water, it ascends within it, and 

 is conducted to the surface through what- 

 ever impurities may exist in the superior 

 strata. The impure water, through which 

 the boring may pass in its descent, being 

 excluded by the pipe from mixing with 

 the pure water ascending from below. 

 The height to which these springs will 



rise above the surface must depend on 

 the quantum of hydrostatic pressure from 

 below ; this is sometimes very great. The 

 water of an Artesian well in Rousillon 

 rises from thirty to fifty feet above the 

 surface. At Perpignan and Tours, M. 

 Arago states that the water rushes up 

 with such extreme force as violently to 

 eject a cannon ball placed in the pipe. 

 An economical and easy method of sink- 

 ing Artesian wells has recently been prac- 

 tised. Instead of the tardy and costly 

 process of boring with a number of iron 

 rods screwed to each other, one heavy 

 bar of cast iron, about six feet long, and 

 four inches in diameter, armed at its 

 lower end with a cutting chisel, and sur- 

 rounded by a hollow chamber, to receive 

 through valves, and bring up the detritus 

 of the perforated stratum, is suspended 

 from the end of a strong rope, which 

 passes over a wheel or pully fixed above 

 the spot in which the hole is made. As 

 this rope is moved up and down over the 

 wheel, its tortion gives to the bar of iron 

 a circular motion, sufficient to vary the 

 place of the cutting chisel at each descent. 

 When the chamber is full, the whole 

 apparatus is raised quickly to the surface 

 to be unloaded, and is again let down by 

 the action of the wheel. Buckland. 



ARTI'CULAR. (articularis, Lat. articu- 

 laire, Fr. articolare, It.) Belonging to 

 the joints. 



ARTICULA'TA. One of the four great ex- 

 isting divisions of the animal kingdom ; 

 the third in Cuvier's arrangement, the 

 other three being the Vertebrata, the Mol- 

 lusca, and the Radiata. The earliest 

 examples furnished by geological research, 

 of articulated animals, or such as belong 

 to the division Articulata, are those af- 

 forded by the extinct family of Tri- 

 lobites. This division of the animal 

 kingdom comprehends four classes : 1. 

 The Annelidans, or worms with red blood ; 

 2. The Crustaceans, as the lobster, 

 shrimp, &c.; 3. The Arachnidans ; 4. In- 

 sects. In the Articulata is observed the 

 transition from circulation in closed ves- 

 sels to nutrition by imbibition, and the 

 corresponding transition from respi- 

 ration in circumscribed organs to that 

 effected by tracheae, or air vessels, dis- 

 tributed through the body. This third 

 division of the animal kingdom has been 

 named by Professor Grant, Diplo-Neura. 

 It comprises Crustacea, Arachnida, In- 

 secta, Myriapoda, Annelida, Cirrhopoda, 

 Rotifera, and Entozoa. In the Crus- 

 tacea, the nervous system is disposed in 

 the form of two abdominal chords, and 

 this form can be traced through the whole 

 of the third division, from Crustacea to 

 Entozoa inclusive. 



