4 ACETIC ACID 



Desert, as does also A. Ehrenbergii, their gums being collected by the Bedouin Arabs ; 

 and A. Senegal grows in Arabia and Africa, from Senegal to the Capo of Good Hope. 

 See ABABIC, GUM ; GUM. 



ACACIA CATECHU. The catechu acacia (Mimosa catechu of Linnaeus) is a 

 tree \rith a moderately high and stout stem, growing in mountainous places in various 

 parts of India. Ite unripe pods and wood, by decoction, yield the catechu. This 

 kind of catechu is known under the name of Kutch or Cutch, and must not be con- 

 founded with the official catechu (Catechu pattidum). This catechu is imported in 

 large masses of 1 cwt. and upwards. It is used in the preparation of some leathers 

 and by dyers. See CATECHU. 



ACACXW. A name for common Gum Arabic. 



ACAJOU (BOXS '). The French name for mahogany. See MAHOGANY. 



ACAROID RESIN. A resin sometimes called Botany Bay resin, produced by 

 a liliaceous tree growing in New Holland. It contains benzoic and cinnamic acids, 

 which give it, especially when burnt, a grateful odour. 



ACESCENT. Substances which have a tendency to pass into an acid state ; as 

 an infusion of malt, &c. 



ACETAZi. C 12 H I4 4 . (CH H O ;! ). One of the products of the oxidation of 

 alcohol under the influence of oxygen condensed in platinum-black. Pieces of well- 

 cleaned pumice-stone are moistened with nearly absolute alcohol, and placed at the 

 bottom of a wide-mouthed flask, which is then filled with capsules containing 

 platinum-black, and exposed to a temperature of 20 Cent. (67 Fahr.), till the whole 

 of the alcohol is acidified. It is a colourless, mobile, ethereal liquid, boiling at 221 F. 

 Its density in the fluid state is 0-821 at 72. The specific gravity of its vapour 

 4-138 Stas. (mean of three experiments) : calculation gives 4'083 for four volumes 

 of vapour. The researches of Wurtz render it evident that the construction o- 

 acetal is quite different from what has generally been supposed, and that it is 

 in fact glycole in which two atoms of hydrogen are replaced by two of ethyle. 

 C. G. W. 



ACETATE. (Acetate, Fr. ; Essigs'dure, Ger.) Any saline compound in which 

 the acid constituent is acetic acid. All acetates are soluble in water; the least 

 soluble being the acetates of tungsten, molybdenum, silver, and mercury. The 

 acetates, especially those of lead and alumina, are of great importance in the arts. 

 The acetates are all described under their respective bases ; a rule which will be 

 adopted with all the acids. See Aero. 



ACETIC ACID. (Acide acetique, Fr. ; Essigs'dure, Ger. ; Acidum aceticum, 

 Lat. ; Eisel, Sax.) The word ' acetic ' is derived from the Latin acetum, applied to 

 vinegar ; probably the earliest known body possessing the sour taste and other 

 properties which characterize acids ; hence the term ACID, now become generic ; both 

 the Latin word, and also the Saxon acid, being from the root acics (Greek OK};), an 

 edge or point, in reference to the sharpness of the taste. 



Vinegar must have been known from the most remote periods of antiquity. It is 

 mentioned by Moses. 1 Hippocrates employed it in medicine under the name ot/s.- 

 Hannibal, in his passage over the Alps, is said to have softened the rocks by fire and 

 vinegar. 3 It was known to the alchemists in the more concentrated state in which 

 it is obtained by the distillation of acetate of copper (verdigris) ; being mentioned 

 both by Geber 4 and Stahl. 



Crystallised acetic acid was first obtained by Westendorff * and Lowitz.* 



Acetic acid exists in nature only in the organised kingdoms, or as a product of the 

 oxidation of organic bodies. According to Vauquelin and Morin it is found in the 

 juices of certain plants, and it probably exists in certain animal fluids. 



Gmelin and Geiger state that it has been found in mineral waters, which is quite 

 possible, having been derived from the decay of organic matter originally present. 



Acetic acid is produced either by the oxidation, or the destructive distillation of 

 organic bodies containing its elements carbon, hydrogen, and oxygen. 



The oxidation of organic bodies, in order to convert them into acetic acid, may bo 

 effected either 1, by exposing them in a finely divided state to the action of air or 

 oxygen gas ; 2, by submitting them to the action of ferments in the presence of a 

 free supply of atmospheric air ; or, 3, by the action of chemical oxidising agents. 



When acetic acid is procured by the oxidation of organic bodies, it is generally 

 alcohol that is employed ; but by whatever process alcohol is transformed into acetic 

 cid, it is always first converted into an intermediate compound, aldehyde ; and this 



1 Numbers, vi. 3. De Natura Mnliebrl. 



Livy. * Investigation of Perfection. 



8 WestendorlT, Diss. do Opt. Acet. Cone. Gottcnburg, 1772. 

 iowitu, Allgem. Journal von Likerer, III, 600. 



