276 VINEGAR, CIDER, AND FRUIT-WINES. 



agitated to free it as much as possible from the tar. After 24 

 hours the solution is drawn off. The iron being entirely coated 

 with tar so that it is not again attacked by the wood- vinegar, it 

 is taken from the vat and the tar ignited. The iron being freed 

 from the oxide formed by sifting can be again used. The solu- 

 tion thus obtained shows 13 or 14 B. 



The pure salt is obtained by dissolving iron in acetic acid or by 

 double decomposition from ferrous sulphate (14 parts) and lead 

 acetate (19 parts); and cheaper, but less pure, from ferrous sul- 

 phate and calcium acetate. 



If crude calcium acetate instead of wood- vinegar is to be used 

 in the preparation of this salt, a solution of the calcium acetate 

 of specific gravity 1.08 is mixed with half its weight of ferrous 

 sulphate dissolved in 2J times its weight of water. On agitating 

 the mixture the decomposition is rendered complete, the clear 

 liquor which is siphoned off after the subsidence of the sulphate 

 of lime showing 13 B. It is kept in a closed barrel in which is 

 hung a bag containing a quantity of iron turnings. 



In some factories the ferrous acetate is manufactured by de- 

 composing the carbonate of iron (FeCO 3 ) with lead acetate ; lead 

 carbonate precipitates, and the blackish supernatant liquor is the 

 acetate of iron in a very pure state. It is kept from oxidizing 

 by immersing in it some bright iron filings. The lead salt 

 formed repays the cost of the manufacture of the acetate. 



Solution of ferrous acetate is used as a mordant by dyers, for 

 staining wood and leather and in the manufacture of ink. The 

 commercial article generally shows a specific gravity of 1.10 

 (12 B.). 



On account of the avidity with which ferrous acetate absorbs 

 oxygen, it is of great value as a reducing agent. It is, for instance, 

 used in the preparation of aniline from nitrobenzole and for 

 similar reducing processes. 



Neutral ferric acetate or sesquiacetate of iron, Fe(C 2 H 3 O 2 ) 3 . 

 For technical use this combination is obtained by dissolving 

 wrought-irou in wood-vinegar so that it has a chance to oxidize 

 in the air. For this purpose wood-vinegar is poured over iron 

 turnings in a vat, and after drawing off the solution, in a few days 

 the iron is for some time left to the action of the oxygen of the 



