ACETIMETRY 15 



All the globes ought to bo perfectly clean and dry. The distillation is to be con- 

 ducted in the usual way. If we divide the product into thirds, the first yields tho 

 feeblest acid, and the third the strongest. Wo could not push the process quite to 

 dryness, because there remain in the last portions certain impurities which would 

 injure tho flavour of the acid. 



The total acid thus obtained forms nearly one-half of the weight of the acetate 

 employed, and the residuum forms three-tenths ; so that about two-tenths of the acid 

 have been decomposed by the heat, and are lost. Urc. 



Other metallic acetates may be used instead of the acetate of copper, but with 

 variable results as to the amount of acetic acid which they yield. Acetates which 

 have easily reducible oxides as those of copper, silver, mercury, lead, &c. afford 

 a larger proportion of acetic acid ; but acetone and marsh gas, as well as carbonic oxide 

 and carbonic acid, invariably accompany it. The acetate of silver gives no acetone ; 

 whilst those of the alkaline earths yield chiefly acetone or marsh gas, and are converted 

 into carbonates. See ACETONE. 



Anhydrous Acetic Acid, as made by Gerhardt, is obtained by mixing perfectly dry 

 fused acetate of potash with about half its weight of chloride of benzoyle, and ap- 

 plying a gentle heat ; when a liquid distils over, which, after being rectified, has a 

 constant boiling point of 279 F., and is heavier than water, with which it does not 

 mix until after it has been agitated with it for some time. It dissolves at once in hot 

 water, forming acetic acid. 



Uses of Acetic Acid, 



Acetic acid is extensively employed in the arts, in tho manufacture of the various 

 acetates, especially those of alumina and iron, so extensively employed in calico- 

 printing as mordants, sugar of lead, &c. It is likewise used in the preparation of 

 varnishes, for dissolving gums and albuminous bodies; in the culinary arts, especially 

 in the manufacture of pickles and other condiments ; in medicine, externally, as a 

 local irritant, and internally, to allay fever, &c. 



For the treatment in cases of poisoning, we refer to Taylor, Pereira, and other 

 medical authorities. 



For the Manufacture of Vinegar, see VINEGAR. 



ACETIC ETHERS. (Acetate of Ethyl. Essig'dther. Essignaphtha. Essigs'dures 

 Mthyloxyd,.*) These are compounds of acetic acid with the alcohol radicals. See 

 RADICALS, ALCOHOL, and RADICALS, CHEMICAL. 



ACETI1VIETER. An apparatus used in the processes for determining the 

 strength of vinegar. Consult WATTS'S Dictionary of Chemistry. 



ACETIMETRY. Determination of the Strength of Vinegar. If in vinegars, -we 

 were dealing with mixtures of pure acetic acid and water, the determination of tho 

 density might to a certain extent afford a criterion of the strength of the solution ; 

 but vinegar, especially that obtained from wine and malt, invariably contains gluten, 

 saccharine, and mucilaginous matters, which increase its density and render this 

 method altogether fallacious. 



An accurate means of determining the strength of vinegar is by ascertaining the 

 quantity of carbonate of soda or potash neutralised by a given weight of the vinegar 

 under examination. This is performed by adding to the vinegar a standard solution 

 of the alkaline carbonate of known strength from a burette, until, after boiling to 

 expel tho carbonic acid, a solution of litmus previously introduced into the liquid is 

 rendered distinctly blue. 



The details of this process, which is equally applicable to mineral and other organic 

 acids, will be found fully described under the head of ACIDIMETRY. 



Roughly, it may be stated that every 53 grains of the pure anhydrous carbonate of 

 soda, or every 69 grains of carbonate of potassa (i.e. one equivalent), correspond to 

 60 grains of acetic acid (C 1 H 4 0). 



. It is obvious that preliminary examinations should be made to ascertain if sul- 

 phuric, hydrochloric, or other mineral acids are present; and, if so, their amount 

 determined ; otherwise they will be reckoned as acetic acid. 



The British malt vinegar is stated in tho ' London Pharmacopoeia ' to require a 

 drachm (60 grains) of crystallised carbonate of soda (which contains 10 equivalents 

 of water of crystallisation), for saturating a fluid ounce, or 4 -46 grains ; it contains, 

 in fact, from 4'6 to 5 per cent, of real acetic acid. 



The same authorities consider that the purified pyroligneous acid should require 87 

 grains of carbonate of soda for saturating 100 grains of the acid. 



Dr. Uro suggests the use of the bicarbonate of potash. Its atomic weight, referred 

 to hydrogen as unity, is 100'584, while tho atomic weight of acetic acid is 51 '563 ; if 

 we estimate 2 grains of the bicarbonate as equivalent to 1 of the real acid, wo shall 



