ARS 



ARS 



of each arm lying the same way, so that 

 the arm is every where of an equal thick- 

 ness, and all of them terminating at the 

 edge of the escutcheon, like the plain 

 cross. 



ARSENAL, in military affairs, in a 

 large and well fortified town, is a spa- 

 cious building, in which are deposited all 

 kinds of arms, and other warlike imple- 

 ments, such as cannon, mortars, howit- 

 zers, small arms, and every other warlike 

 kind of engines and instruments of 

 death. 



ARSENIATES, in chemistry, a genus 

 of salts, formed from arsenic acid and some 

 particular base ; thus we have the arseni- 

 ates of potash, the arseniates of soda, lime, 

 &.c. They are distinguished by the fol- 

 lowing property : when heated with char- 

 coal powder, they are decomposed, and 

 the arsenic sublimes. These salts have 

 not hitherto been applied to any useful 

 purpose, and have at present been but 

 superficially examined. 



ARSENIC, in mineralogy, one of the 

 metals that are brittle and easily fused. 

 The word occurs first in the works of 

 Dioscorides, and other authors, who 

 wrote about the beginning of the Chris- 

 tian <era; it denotes in their works the 

 same substance which Aristotle had called 

 <rae.v^ctf>cc^, which is a reddish-coloured 

 mineral, composed of arsenic and sulphur, 

 used by the ancients in painting, and as 

 a medicine. 



ARSENIC, as it is to be found in the 

 shops, occurs in the state of a white ox- 

 ide, from which the metal may be obtain- 

 ed by the following process. Mix two 

 , parts of the white oxide with one part of 

 black flux (prepared by detonating in a 

 crucible one part of nitre with two of 

 crystals of tartar), and put the mixture 

 into a crucible, invert over this another 

 crucible ; lute the two together, by a mix- 

 ture of clay and sand, and apply a red 

 heat to the lower one. The arsenic will 

 be reduced, and will be found lining the 

 inside of the upper crucible, in a state of 

 metallic brilliancy. Arsenic is oxidized 

 by mere exposure to the atmosphere. It 

 soon becomes tarnished, loses its metal- 

 lic lustre, and is changed into a blackish 

 oxide. It is readily fusible, and is vola- 

 tilized at 356. In close vessels it may 

 be collected unchanged; but when thrown 

 on a red hot iron, it burns with a blue 

 flame and a white smoke, and a strong 

 smell of garlic is perceived. All the mi- 

 neral acids act on arsenic ; but not consi- 

 derably, unless they are heated. In the 



oxigenized muriatic acid gas, however, 

 arsenic burns vehemently. A mixture of 

 oxymuriate of potash and arsenic furnishes 

 a detonating compound, which takes fire 

 with the rapidity of lightning-. The salt 

 and metal, first separately powdered, may 

 be mixed by the gentlest possible triture, 

 or rather by stirring them together on pa- 

 per with a knife point. If two long trains 

 be laid on a table, the one of gunpowder, 

 and the other of this mixture, and they be 

 in contact with each other at one end, so 

 that they may be fired at once, the arseni- 

 cal mixture burns with the rapidity of 

 lightning, while the other burns with com- 

 paratively extreme slowness. Arsenic has 

 the property of giving a white stain to 

 copper. Let a small bit of metallic ar- 

 senic be put between two small plates of 

 copper ; bind these closely together with 

 iron wire, and heat them barely to red- 

 ness in the fire. The inside of the cop- 

 per plates will be stained white. The 

 white oxide of arsenic has the following 

 properties : 1. It has an acrid taste, and 

 is highly poisonous. 2. It is soluble in 

 water, which, at the ordinary temperature, 

 takes up l-80th. According to La Gi ange, 

 it is soluble in l-24th of cold water, or 

 l-15th of hot. 3. Oxide of arsenic com- 

 bines with the pure alkalies to saturation ; 

 and hence it fulfils one of the principal 

 functions of an acid. It has therefore 

 been called arsenous acid, and its com- 

 pounds arsenites. They may be formed 

 by simply boiling the acid with a pure al- 

 kaline solution. 4. The arsenous acid, by 

 distillation with sulphur, affords either a 

 yellow substance, called orpiment, or a 

 red one, termed realgar. Both these com- 

 pounds are sulphuretted oxides of arsenic, 

 varying in the proportion of their com- 

 ponents. The hydro-sulphurets also 

 throw down a yellow precipitate from so- 

 lutions of arsenous acid. Sulphate of 

 copper, mixed with arsenite of po'ash, 

 gives a beautiful precipitate, called,, from 

 its discoverer, Scheele's gr^en. 5. By 

 repeated distillation with nitric acid, ar- 

 senous acid ;s changed into arsenic acid. 

 The same change is effected also by ex- 

 posure to the vapour of oxigenized mu- 

 riatic acid, and the expulsion, by heat, of 

 the common muriatic acid. By both 

 these processes, a white cor Crete sub- 

 stance is obtained, termed arsenic acid. 

 The arsenic acid has a sour, ana at the 

 same time a metallic taste. It reddens 

 vegetable blues, attracts humidity from 

 the atmosphere, and effervesces strong- 

 ly \\:lh solutions of alkaline carbonates. 

 With alkalies, earths, and oxides, it con- 



